Skokomish River comprehensive flood control management plan draft plan : internal review draft

[From the U.S. Government Printing Office, www.gpo.gov]

SKOKOMISH RIVER
COMPREHENS IVE FLOOD CONTROL MANAGEMENT PLAN:

DRAFT PLAN

Internal Review Draft

July 1987

COASTAL ZONE
INFORMATION CENTER

Douglas J. Canning,
Lisa Randlette,
and William A. Hashim
TC
24 Flood Plain Management Section
.W2 Shorelands and Coastal Zone Management Program
C36 WASHINGTON DEPARTMENT OF ECOLOGY
1987 Olympia, Washington 98504-8711

xx July 1987

Dear Reader:

The attached Draft Skokomish River Comprehensive Flood Control Management Plan
(CFCMP) is a model plan prepared by the Shorelands and Coastal Zone Management
Program Flood Plain Management Section. The preparation of local CFCMPs was
initiated by the 1984 state legislature in amendments to Chapter 86.26 RCW,
State Participation in Flood Control Maintenance.

The legislation provides that state participation in funding of flood control
maintenance projects shall be conditional on completion and adoption of a local
"comprehensive flood control management plan" (RCW 86.26.050). The legislature
further directed that a CFCMP shall:

determine the need for flood control work;

consider alternatives to instream flood control work;

identify and consider potential impacts of instream flood
control work on the state's instream resources; and

identify the river's meander belt or floodway (RCW
86.26.105).

Local CFCMPs must be approved by the Department of Ecology in consultation with
the state departments of Fisheries and Game (RCW 86.26.050). Ecology's regula-
tory guidelines for preparation of CFCMPs (WAC 173-145-040) were adopted in
1985 and amended in early 1987.

The requirement for comprehensive flood control planning is new to Washington's
local governments. Therefore, this model plan has been prepared as further
guidance to local governments in preparation of their own CFCMPs. This plan
has been prepared in consultation with the state departments of Fisheries and
Game, Mason County, and the Skokomish Indian Tribe.

The purpose of this draft Skokomish River CFCMP is to provide the public, par-
ticularly the residents of the Skokomish Valley, local government officials and
staff, affected state agencies, and other interested parties, the.opportunity
to comment on the approaches to comprehensive flood control planning in this
model plan.

This marks the beginning of the public review period for the draft Skokomish
River CFCMP. We invite both your general comments on the CFCMP concept, plus
your specific comments on the recommendations of the draft Skokomish River

i i i

CFCMP. To be considered in our preparation of the final Skokomish River CFCMP,
written comments must be received by July xx, 1987, and should be sent to:

Skokomish River Project
Shorelands & CZM Program, PV-11
Washington Department of Ecology
Olympia, WA 98504-8711
Attn: Lisa Randlette, Project Manager

Sincerely,

D. Rodney Mack, Manager
Shorelands & CoaCstal Zone Management Program

EXECUTIVE SUMMARY
The Skokomish Valley, located in north central Mason County, is an agricultural
and rural residential area which floods once or more a year during a typical'
winter rainy season. Other important land uses in the valley include three
state fish hatcheries. The Skokomish Indian Reservation lies at the mouth of
the river on Hood Canal.

Flow into the main stem Skokomish River and Skokomish Valley is principally
from the South Fork Skokomish basin which drains the southeasterly portion of
the Ol'ymoic National Forest. The North Fork Skokomish, which drains the south-
easterly portion of Olympic National Park, was diverted out of the Skokomish
basin in 1930 as part of a City of Tacoma hydroelectric project.

The Skokomish Valley has been evaluated for flood protection in the past by the
US Army Corps of Engineers, the Pacific Northwest River Ba sins Commission, and
the US Soil Conservation Service. The cost of flood protection has, and con-
tinues to exceed the benefits.

The Skokomish Valley has never experienced a major -- that is 100-year -- flood
during historical times. The largest flood was a 30-year event in 1955. The
annual low level flooding results from rainfall events of up to 5- to 10-year
intensities which sheet flow across the valley and drain via old secondary
channels. Drainage has been impeded by the filling of some old chanfiels and
meanders, as well as*by the damming effect of the US 101 highway.

The frequency and severity of the annual flooding is increasing. Flood waters
rise rapidly, and usually last a day or two. The problems associated with the
annual flooding are:
water damage to structures and personal property;
soil erosion of bare, unprotected farm fields;
damage to crops such as corn and Christmas trees;
stranding and interrupted transportation;
severe streambank erosion in certain locations; and
emergency evacuation.
The cause of the increase in flooding is an aggrading -- filling -- riverbed.
During the past twenty years the riverbed-at the US 101 bridge has risen three
feet and the flow necessary to top the riverbanks has decreased from 10- 12,000
cfs (cubic feet per second) to 8,500 cfs.

The source of the gravel and sediments filling the Skokomish River is primarily
from the South Fork Skokomish basin. Slopes in the South Fork basin are steep
and unstable, and soils are susceptible to erosion. Forest practices within
the Shelton Cooperative Sustained Yield Unit of the Olympic National Forest are
suspected but not yet confirmed as a contributing factor.

The effect of aggradation on instream fish habitat is unknown but could be det-
rimental.

The Skokomish River main stem flows along the north side of the Skokomish Val-
ley. The valley floor slopes toward the south side of the valley. As riverbed
aggradation continues there is an increasing likelihood that a large flood flow
will cause the river to carve a new main channel south across the valley to new
location along the south side. The potential damage resulting from a such an

event might include:
destruction of fish hatcheries through undercutting of fill
washout of US 101, a major transportation link
destruction of structures
loss of life

There is no immediate, affordable solution which will eliminate the chronic,
annual flooding problem of the Skokomish Valley, or the catastrophic potential
of the river jumping its banks and carving a new channel.

The chronic problem can be ameliorated through the following institutional mea-
sures:
development of a better warning and evacuation system
elevation of roadways
and the following individual measures which may require financial and/or tech-
nical assistance:
flood proofing of structures
agricultural practices adapted to flooding
bank protection measures not harmful to fish habitat

The catastrophic potential shoul d be assessed first through a detailed study of
South Fork basin erosion, landsliding, and sediment transport from the South
Fork to the main stem, plus streambank erosion in the Skokomish Valley. Only
then can the magnitude of the problem be identified and potential solutions be
evaluated for implementation.

TABLE OF CONTENTS

Letter of Transmittal . . . . . . . . . . . . . . . . . . . . . . . . iii

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Table of Contents . . . . . . . . . . . . . . . . . .. . . . . . . . . . vii

CHAPTER 1, INTRODUCTION . . . . . . . . . . . : * * * * ' * ' ' * * * ' I
Need for Comprehensive Flood Control Planning . . . . . . . . . . . 1
Flood Control Assistance Account Program . . . . . . . ... . . . . 1
Skokomish River Comprehensive Flood Control Plan . . . . . . . . . 1

CHAPTER 2, PRINCIPALS AND CONCEPTS OF THE PLAN . . . . . . . . . . . . 7
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
The Watershed as a Planning Unit . . . . .. . . . . . . . . . . . . 7
Relationship of the Watershed to the Region . . . . . . . . . . . 7
Basic Principals of Comprehensive Flood Control Management Planning 8
Comprehensive Flood Control Management Planning Process . . . . . . 8
Study Design . . . . . . . . . . . . . . . . . . . . . . . . 8
Objectives . . . . . . . . . . . . . . . .. . . . . . . . . . 9
Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Analysis of Inventory . . . . . . . . . . . . . . . . . . . . 9
Plan Development and Evaluation of Alternatives . . . . . . . 9
Plan Selection and Implementation . . . . . . . . . . . . . . . 9

CHAPTER 3, SKOKOMISH RIVER WATERSHED CHARACTERISTICS . . . . . . . . . 11
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Natural Systems . . . . . . . . . . . . . . . . . . . . . . . . . 11
Climate . . . I. . . . . . . ... . . . . . . . . . . . . . . 11
Physiography . . . . . . . . . . . . . . . . . . . . . . . . 12
Geology . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Water Reso urce s . . . . . . . . . . . . . . . . . . . . . . . 22
Water Quality . . . . . . . . . . . . . . . . . . . . . . . . 25
Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Fisheries . . . . . . . . ... . . . . . . . . . . . . . . . . 29
Wildlife ... . . . . . . . . * ' : : * * * * * I * I I * * 131
Special Plants, Animals, and Communities . . . . . . . . . . 32
Socioeconomic Systems . . . . . . . . . . . . . . . . . . . . . . 33
Political Subdivisions . . . . . . . . . . . . . . . . . . . . 33
Population and Housing . . . . . . . . . . . . . . . . . . . 35
Economic Sectors . . . . . . . . . . . . . . . . . . . . . . 35
Land Use : * * * * * * * * * * ' * * * * * * * * I I * * I *36
Public Services and Utilities . . . . . . . . . . . . . . . . 37
Transportation . . . . . . . . . . . . . . . . . . . . . . . 38
Recreation . . . . . . . . . . . . . . . . . . . . . . . . . 39
Cultural Resources . . . . . . . . . . . . . . . . . . . . . 40
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

CHAPTER 4, HYDROLOGY AND HYDRAULICS . . . . . . . . . . . . . . . . . . 43
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

vii

TABLE OF CONTENTS, Continued:

CHAPTER 4, Continued
Climate . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . 43
Precipitation . . . . . . . . . . . . . . . . . . . . . . . . 43
Snow Cover . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Evaporation . . . . . . . . . . . . . . . . . . . . . . . . . 43
Hydrology . : * * * * I I I * * * * I * I * * * * I * * * I I * * 44
Introduction . . . . . . . . . . . . . . . . . . . . . . . . 44
Skokomish River System . . . . . . . . . . . . . . . . . . . . 46
Flooding . . * * * * : * * * * * * * * * * * * ' * * * * 52
Pre-settlement Ch@ra*ct*Or*is*tics . . . . . . . . . . . . . . . 53
Current Flooding Characteristics . . . . . . . . . . . . . . 54
Summary and Conclusions . . ... . . . . . . . . . . . . . . . . . 59

CHAPTER 5, HISTORIC.FLOOO DAMAGES AND PLANNING . . . . . . . . . . . . 63
Introduction . . . . . . . . . . . . . . .. . . . . . . . . . . . . 63
Historic Flood Control Measures . . . . . . . . . . . . . . . . . 64
State Flood Control Participation . . . . . . . . . . . . . . 64
State Flood Control Zone Permits . . . . . . . . . . . . . . 65
Hydraulic Project Approval Records . . . . . . . . . . . . . 65
Damage Cost Estimates . . . . . . . . . . . . . . . . . . . . . . 67
Chronic Problems and Problem Areas . . . . . . . . . . . . . . . . 68
Prior Flood Control Investigations and Plans . . . . . . . . . . . 69
US Army Corps of Engineers, 1942 . . . . . . . . . . . . . . 69
US Soil Conservation Service, 1964 . .. . . ... . . . . . . . 70
Puget Sound and Adjacent Waters Study, 1970 . . . . . . . . . 70
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

CHAPTER 6, SKOKOMISH BASIN REGULATORY PROGRAMS . . . . . . . . . . . . 73
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Land Use and Shoreline Management . . . . . . . . . . . . . . . . . 73
Mason County Building Code . . . . . . . . . . . . . . . . . 73
Mason County Zoning and Comprehensive Plan . . . . . . . . . . 73
Mason County Shoreline Master Program . . . . . . . . . . . . 74
Resource Management . . . . . . . . . . . . . . . . . . . . . . . . 78
Hydraulic Project Approval . . . . . . . . . . . . . . . . . 78
Department of the Army Permit . . . . . . . . . . . . . . . . 78
Water Quality Certification . . . . . . . . . ... . . . . . . 79
Flood Control and Floodplain Management . . . . . . . . . . . . . . 80
National Flood Insurance Program . . . . . . . . . . . . . . 80
FEMA Floodway Mapping, 1987 . . . . . . . . . . . . . . . . . 81
Flood Control Zone Act . . . . . . . . . . . . . . . . . . . 83
Mason County Floodplain Regulations . . . . . . . . . . . . . 84
Coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
CHAPTER 7, ALTERNATIVE FLOOD CONTROL MANAGEMENT MEASURE'S . . . . . . .. 87
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Nonstructural Measures . . . . . . . . . . . . . . . . . . . . . . 88
Introduction . . . . . . . . . . . . . . . . . . . . . . . . 89
Flood Damage Reduction . . . ... . . . . . . . . . . . . . . 90
Development Policies . . . . . . . . . . . . . . . . . . . . 90
Flood Warning and Forecasting . . . . . . . . . . . . . . . . 90

viii

TABLE OF CONTENTS, Continued:

CHAPTER 7, Continued

Disaster Plans . . . . . . . . . . . . . . . . . . . . . . . 92
Flood Proofing . . . . . . . . . . . . . . . . . . . . . . . 93
Structure Relocation . . . . . . . . . . . . . . . . . . . . 93
Land Regulations . . . . . . . . . . . . . . . . . . . . . . 93
Disclosure . . . . . . . . . . . . . . . . . . . . . . . . . 93
Public Information Programs . . . . . . . . . . . . . . . . . 93
Flood Recovery . . . . . . . . . . . . . . . . . . . . . . . 93
Flood Insurance . . . . . . . . . . . . . . . . . . . . . . . 94
Flood Emergency Operations . . . . . . . . . . . . . . . . . . 94
Financial Assistance For Recovery . . . . . . . . . . . . . . 94
Structural Measures . . . . . . . . . . . . . . . . . . . . . . . 95
Streambank Stabilization . . . . . . . . . . . . . . . . . . 95
Storage of Floodwaters . . . . . . . . . . . . . . . . . . . . 95
Dikes and Levees . . . . . . . . . . . . . . . . . . . . . . 95
Instream Work . . . . . . . . . . . . . . . . . . . . . . . . 96
Flood Diversion . . . . . . . . . . . . . . . . . . . . . . . 96
Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . 96

CHAPTER 8, RECOMMENDED FLOOD CONTROL MANAGEMENT PLAN . . . . . . . . . 99
Introduction . * * * ' * ' ' * * ' * . * * ' * * . * ' ' *99
Flood Control Management Alternatives . ... . . . . . . . . . . 100
Alternative 1: Continue Existing Practices . . . . . . . . 100
Alternative 2: Emergency Preparedness . . . . . . . . . . . 101
Alternative 3: Flood Proofing of Structures . . . . . . . . 102
Alternative 4: Storage of Flood Waters . . . . . . . . . . . 104
Alternative 5: Watershed Management . . . . . . . . . . . . 105
Alternative 6: Channel Capacity . . . . . . . . . . . . . . 106
Alternative 7: Diking . . . . . . . . . . . . . . . . . . . 108
Alternative 8: Bank Stabilization . . . . . . . . . . . . . 109
Alternative 9: Instream Diversions in Critical Areas . . . . 110
Long Term Recommendation . . . . . . . . . . . . . . . . . . . . III
Summary and Recommendations . . . . . . . . . . . . . . . . . . . 112

REFERENCES CITED AND CONSULTED . . . . . . . . . . . . . . . . . . . . 113

LIST OF TABLES.
3.1 River Mile Locations of Prominent Riverine Features,
Skokomish Basin, Washington . . . . . . . . . . . . . . . . . . . 18

3.2 Soils Characteristics, Skokomish Valley, Mason County, Washington 23

3.3 Comparisons of Runoff from Selected Puget Sound River Basins . . . 25

3.4 Selected Peak Flows, Main Stem, Skokomish River . . . . . . . . . 26

3.5 Class AA Water Quality Standards, Washington . . . . . . . . . . . 26

3.6 Salmon Releases from George Adams Hatchery, Purdy Creek,
Skokomish Basin, Washington, 1982 - 1986 . . . . . . . . . . . . . 31

TABLE OF CONTENTS, Continued:

LIST OF TABLES, Continued

3.7 Known Occurrences of Special Plants, Animals, and Communities,
Skokomish Valley, Mason County, Washington . . . . . . . . . . . . 32

3.8 Mason County Population (1980 - 1986) and Forecast (1990 - 2000). . 36

3.9 Shelton CYSU Average Annual Timber Harvest . . . . . . . . . . . . 37

3.10 Characteristics of Cushman I and Cushman II Hydropower
Facilities, North Fork Skokomish River . . . . . I. . . . . . . . . 38

4.1 Estimated Existing Annual Runoff Characteristics, Skokomish Basin 45

4.2 River Gradient, Morphology, and Bed Material Model . . . . . . . . 46

4.3 Discharge Statistics, Skokomish River System . . . . . . . . . . . 47

4.4 Predicted Peak Discharges, Skokomish River System . . . . . . . . 53

5.1 Estimated Flood Damages, Skokomish Valley . . . . . . . . . . . . 67
5.2 Flood Control Alternatives, PSAW Study, 1970 ... . . . . . . . . . 71

6.1 Agricultural and Residential Shoreline Regulations . . . . . . . . 77

7.1 Federal Disaster Assistance Grants, Mason County . . . . . . . . . 95

LIST OF FIGURES

3.1 Skokomish River Basin . . . . . . . . . . . . . . . . . . . . . . 13

3.2 Skokomish Valley . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.1 Diagram of Cushman Project Diversions . . . . . . . . . . . . . . 48

4.2 Skokomish 'Valley Channel Patterns . . . . . . . . . . . . . . . . 49
4.3 Skokomish Valley Low Level Flooding Patterns .. . . . . . . . . . . 57
6.1 Flood Plain Schematic Cross Section . . . . . . .. . . . . . . . . 84

APPENDICES
A. Skokomish River Hydrology

B. Historic Flood Control Work

C. Skokomish Valley Photographs

Chapter 1

INTRODUCTION

The Skokomish River Comprehensive Flood Control Management Plan has been devel-
oped by the Flood Plain Management Section of the Shorelands and Coastal Zone
Management Program, in the Department of Ecology. This model plan is intended
to serve as an example of content and level of detail for local governments
which intend to prepare comprehensive flood control management plans.

NEED FOR COMPREHENSIVE FLOOD CONTROL MANAGEMENT PLANNING
State Participation in Flood Control Maintenance, Chapter 86.26 of the revised
Code of Washington (RCW), is a 1984 law requiring each jurisdiction desiring
state assistance for flood control maintenance to prepare a comprehensive flood
control management plan (CFCMP). The purpose of-comprehensive flood control
management planning is to establish the need for flood control maintenance
work, define structural alternatives, identify and consider potential impacts
of instream flood control work on instream resources, and identify the river's
floodway.
Comprehensive flood control management planning Is intended to reduce flood
damages and to establish, in a prioritized manner, the appropriate structural
and nonstructural measures needed to reduce flood damages. The extent of the
study area may include the entire watershed or, as a minimum, the one-hundred
year frequency flood plain within a reach of the watershed of sufficient length
to ensure that a comprehensive evaluation can be made of the flood problems for
a specific reach of the watershed.

FLOOD CONTROL ASSISTANCE ACCOUNT PROGRAM
In 1984 the Washington State Legislature made significant modifications to the
State Participation in Flood Control Maintenance Act (Chapter 86.26 RCW),
originally enacted in 1951. The 1951 law had provided a funding mechanism to
cost share with local jurisdictions in the construction of facilities for flood
control maintenance. Typical projects included the installation of rock riprap
on eroding streambanks or on failing existing riprap or levees. Funding was
based on a legislative appropriation each biennium with the amount varying from
a maximum of two million dollars per biennium, to no funding for approximately
the last ten years.

The 1984 legislative amendments to the Flood Control Assistance Account Program
(FCAAP; RCW 86.26.007) were based, in part, on the need to protect the invest-
ment of state and local funds allocated for the protection of public facilities
or flood control structures, located on or near streambanks and coastal areas,
from damage and to guide in the wise allocation of those resources. In addi-
tion, it has become widely accepted that the use of structural measures only to
reduce flood damages is not adequate and that nonstructural measures such as
floodproofing and land use restrictions are necessary. Flood damages have been
shown to be increasing at a more rapid rate that the rate of increase in expen-
ditures for structural measures. The implementation of the National Flood In-
surance Program (NFIP) in 1968, and the associated requirement of local flood
plain management ordinances as a nonstructural means of reducing flood damages,

has been a major federal effort in encouraging local governments and private
citizens to mitigate flood losses.

The primary elements of the current State Participation in Flood Control Main-
tenance law are summarized as follows:

Funding: A flood control assistance account Was established with Four Million
Dollars as the initial appropriation for the biennium beginning 1 July 1985.
At the beginning of each succeeding biennium, the account is to be reestab-
lished'at'the initial funding level.

Eligible Applicants: Counties, cities, and other local municipal corporations
with flood control responsibilities such as flood control districts or diking
districts, are eligible to receive state funding for flood control maintenance
projects.

Eligibility Requirements: To address the concerns with previous legislation
regarding the "band aid" approach to flood control maintenance, two significant
eligibility requirements were established. These are flood plain management
activities and comprehensive flood control management planning.

Flood Plain Management Activities: In order to receive funding for flood con-
trol maintenance projects, the Department of Ecology must approve the'flood
plain management activ'ities of the county, city,,or town having planning juris
diction over the area where the particular project will be located. The De-
partment of Ecology is also required to adopt rules concerning these flood
plain management activities to ensure that they are adequate for protection of
development from flood damages and to restrict land uses within the floodway to
only flood-compatible uses. No state funding is provided for flood plain man-
agement activities.

Comprehensive Flood Control Management Plans: The legislation.specifies that a
comprehensive flood control management plan (CFCMP) must include the area where
any proposed project is located and provides direction by specifying the fol-
lowing:

A comprehensive flood control management plan shall determine the
need for flood control work, consider alternatives to instream flood
control work, identify and consider potential impacts of instream
flood control work on the state's instream resources, and identify
the river's meander belt or floodway. (RCW 86.26.105)

The legislation allows up to three years for completion and adoption of the
plan. The county engineer must certify on specific project applications
whether a plan has been completed and adopted, or is being prepared. Compre-
hensive plans must be prepared and adopted by the appropriate local authority
and must be approved by the Department of Ecology. One of the key elements of
the legislation passed in 1986 was that state funding can be provided for up to
seventy-five percent of the costs of preparation of comprehensive flood control
management plans.

Nonemergency Projects: The legislation specifies, in general terms, the type
of maintenance work that is considered eligible work for funding. The type of
work considered eligible is for "maintaining and restoring the normal and rea-

sonably stable river and stream channel alignment and capacity ... and in re-
storing, maintaining, and repairing natural conditions, works and structures."
In addition, state participation can include "restoration and maintenance of
natural conditions, works, or structures for the-protection of lands and other
property from inundation or other damage by the sea or other bodies of water."

All projects must also be for public benefit as opposed to those which are
strictly private interests. Projects for individual land owners are therefore
not eligible unless there are adjacent facilities in jeopardy which are owned
or operated by a county or other municipal corporation.

Emergency Projects: The legislation specifies that a portion of the available
funding will be reserved for emergency purposes. The types of projects that
are considered to be of an-emergency nature are those that must be done immedi-
ately to provide protection to life and property.

Consultation With Other Agencies: The fishery resource, primarily salmon and
Steelhead, is a key consideration in performing any activities within the wa-
ters of the State of Washington. The loss of fish habitat as a result of per-
forming construction work in and adjacent to rivers has been identified as a
major concern by fisheries agencies and Indian tribes.

To ensure that fishery resources are maintained, the legislature provided re-
view authority by the state departments of Fisheries and Game for essentially
all phases of the Flood Control Assistance Account Program. In addition to
their existing approval authority for work done in and adjacent to waters of
the state, the legislature provided that the departments of Fisheries and Game
be consulted prior to Department of Ecology approval of application for spe-
cific projects, flood plain management activities, and comprehensive flood con-
trol management plans.

SKOKOMISH RIVER COMPREHENSIVE FLOOD CONTROL PLAN
The Skokomish River model plan will be the only CFCMP to be undertaken by the
Shorelands and Coastal Zone Management Program of Department of Ecology for the
Flood Control Assistance Account Program. All other CFCMPs will be developed
by local jurisdictions. The Skokomish River watershed was chosen as an example
basin for a comprehensive flood control management plan because it has a number
of unresolved flood control problems.

STUDY OBJECTIVES
The Skokomish River CFCMP was funded through a Coastal Zone Management grant to
the Department of Ecology from the Federal Office of Coastal Resource Manage-
ment. Local jurisdictions require guidance in developing comprehensive flood
control management plans, since the required format and level of detail of such
a plan can be broadly interpreted.
The causes and effects of flood problems are related to the entire watershed
and are most effectively addressed within the context of watershed management.
A watershed study which delineated the flood control related issues and consid-
erations was determined to be an appropriate reference document for local ju-
risdictions. Specifically', the objective of the study is to develop plan el-
ements for the management of the flood plain, including measures for the

mitigation of existing flood problems, and incorporating elements intended to
minimize future flood problems.

A team of Department of Ecology staff was assembled which had a broad back-
ground in basin planning, hydrology, and land use,planning. With limited time
available to develop the study, the team contacted knowledgeable state and lo-
cal specialists with expertise in flood plain management and the related
resource management fields. The team identified basic flood damage problems
within the watershed that required careful areawide study. These problems in-
clude health, safety, and welfare concerns due to limited access and the peri-
odic need for evacuation; damage to agricultural crops, agricultural lands, and
residential and nonresidential structures; and streambank erosion. These prob-
lems are directly related and need to be evaluated and resolved collectively.

The primary benefit of the study for Mason County is to be provided with a
working document with which to develop a detailed comprehensive flood control
management plan. Mason County may also choose to rely upon this CFCMP as an
interim plan, in conjunction with the local flood hazard ordinance, to guide
development and allocation of local funds for public facilities improvements.
It is hoped that the Skokomish River CFCMP will serve as a practical interim
guide for the making of decisions concerning flood plain management within the
watershed.

OTHER MAJOR RELATED STUDIES
During the development of the Skokomish River CFCMP, two related planning ef-
forts were conducted in the watershed.

Skokomish River Flood Damage Reduction Study: The US Army Corps of Engineers
conducted a flood damage reduction study of the Skokomish River. During the
reconnaissance phase, certain structural measures were investigated. These.
measures were:
1) 'Channel modifications in the vicinity of the Skokomish Community Church;
2) Clearing of vegetation upstream of the Highway 101 Bridge;
3) Channel modifications in various areas of the river;
4) Construction of a setback levee; 1 1
5) -Increasing the Highway 101 Bridge opening;
6) Modification of the existing North Fork Skokomish Dam;
7) Excavation of a settling basin; and
8) Excavation of an overflow or bypass channel.

Flood Insurance Study for Mason County: The preliminary Flood Insurance Study
for Mason County was completed the Federal Emergency Management Agency (FEMA)
and made available for public review. A public workshop was held by FEMA at
the Mason County Courthouse on the evening of 7 April 1987. The establishment
of detailed base flood elevations for the Skokomish River Valley was par-
ticularly valuable to the hydrologic evaluation in this study. The Skokomish
River CFCMP will complement the Flood Insurance Study in that detailed recom-
mendations for implementation of a flood damage reduction strategy are par-
tially based upon data developed for flood insurance purposes.

STAFF, COOPERATING AGENCIES, AND MASON COUNTY
Staff of the various state and federal resource agencies served as consultants
and an ad-hoc technical advisory committee. Because of the general nature of
the investigation, and the limited time available to develop the plan, no for-
mal advisory committee was established.

The efforts of the Department's professional and supporting staff were supple-
mented with the services of specialists in selected areas, including surveying,
fish biology, wildlife biology, forestry, hydrogeology, wetland and natural
area identification, and flood hazard reduction.

Chapter 2

PRINCIPLES AND CONCEPTS OF THE PLAN

INTRODUCTION

Watershed planning is a term that means many things to many different inter-
ests. Typically, a single goal, such as hydropower generation, flood control,
wildlife habitat preservation, or soil and water conservation is the purpose
for developing watershed plans. Often, watershed plans do not go far enough in
coordinating with other planning efforts within the watershed or broader re-
gional planning efforts. Properly understanding the flood control management
problems of a jurisdiction requires an examination of the principles of flood
plain management and flood damage reduction. The broader setting of regional
planning efforts which apply to the watershed must also be examined.

THE WATERSHED AS A PLANNING UNIT
A watershed is defined as a geographic drainage area or basin which contributes
surface water runoff to a series of streams and rivers. A watershed also in-
cludes the natural and man-made features within the geographic drainage area
which are interrelated and create a cumulative series of interests, including
land treatment measures, soil and water management practices, and land use pat-
terns within the watershed.

Flood plain management and flood control or storm drain facilities should be
based upon a plan or system which incorporates the entire watershed. This ap-
proach allows consideration of the hydrologic characteristics of the basin.
Streams and rivers must be capable of accommodating present and future an-
ticipated runoff generated by changing conditions within the watershed. The
physical problems of flooding within a watershed identify a community with mu-
tual concerns to be protected. The watershed also serves as a geographic area
for forming special'districts or utilities to address flooding problems.

RELATIONSHIP OF THE WATERSHED TO THE REGION
Individual watershed plans must also consider the broader setting or context of
the region. Land use and environmental problems are not exclusive to indi-
Yidual watersheds and have cumulative impacts upon the region. Flooding, which
is experienced in the lower reaches of the Skokomish River watershed and re-
sults from upstream factors, also affects Hood Canal with accelerated sedimen-
tation and adverse impacts to shellfish areas.
Currentl@, Mason County does not have any regional land use planning in effect.
A shoreline management master program is in place for certain areas along Hood
Canal and other water bodies. Facilities plans such as county roads and parks
are limited in scope. The local flood hazard ordinance, administered through
the Department of Emergency Services, is the most directly related county ef-
fort to flood control planning for the Skokomish River watershed.

The Hood Canal Coordinating Council has the potential to function as a regional
development planning body. Comprehensive flood control management planning
studies for all of,the watersheds in the region would provide a good foundation

by which to address related issues such as water quality and the affect of de-
velopment patterns upon the resource base.

BASIC PRINCIPLES OF COMPREHENSIVE FLOOD CONTROL MANAGEMENT PLANNING
The purpose of developing a comprehensive flood control management plan should
be to initiate public awareness and support for a program of comprehensive
flood control or flood damage reduction strategies in the community. Develop-
ment policies and plans for public improvements and facilities should result
and be long-range, allowing for effective implementation over time.

The following principles guided the development of this study:

1. Watersheds are the appropriate planning unit for developing a comprehensive
flood control management plan.

2. Flood control planning efforts should be mul-tidisciplinary and consider
related water resource and land use problems where applicable.

3. Regional planning efforts and related environmental planning studies should
be considered as a part of developing comprehensive flood control
management plans.

4. Preventative or nonstructural flood control measures should be conducted
in conjunction with structural flood control measures.

5. Hydrologic and hydraulic evaluations must be conducted and include future
capacity and maintenance as a part of any proposed structural facilities.

6. Solutions to flood-related problems should not aggravate or transport prob-
lems to downstream areas.

7. Solutions to flood-related problems should offer a variety of approaches
and solutions which can be accomplished at various levels of community and
government, as well as provide both short- and long-term relief.

COMPREHENSIVE FLOOD CONTROL MANAGEMENT PLANNING PROCESS

STUDY DESIGN
A study design must define the geographic area for which data will be gathered,
specify the content of fact-gathering operations, outline how the information
will be gathered and evaluated, and define the nature of the recommendations
and the criteria used for their local adoption and implementation.

The need for, and objectives of, the Skokomish River CFCMP were established by
the Shorelands and Coastal Zone Management Program of the Department of Ecology
in its capacity of providing technical assistance to local governments in
coastal counties. Through a grant from the Federal Office of Coastal Resource
Management, the major work elements were identified. Ecology staff developed
the scope and content of the proposed CFCMP and solicited comments from con-
sulted resource agency specialists. The CFCMP design was expanded and refined
during development of the plan, and as a result of communications and data con-
tributed by various agencies.

OBJECTIVES
The formulation of objectives involves both technical and nontechnical policy
determinations. The CFCMP is based upon the dual objectives of conducting a
geohydrologic and land use planning evaluation of the problems which result
from river flooding and developing flood damage reduction measures for the wa-
tershed. The primary information used in the investigation includes both re-
connaissance information gathered through site inspections and interviews dur-
ing the course of carrying out this project, plus a review of pertinent
documentary information, especially geologic, hydrologic, and environmental
analyses; flood frequency analyses and flood mapping; economic and financial
analyses of other, prior flood control proposals; and existing land use, flood-
plain management, and environmental regulations.

INVENTORY
Existing data was collected and evaluated for the watershed which addressed:
the characteristics of the watershed; identification of types of watershed
flood problems; location and identification of specific problem areas; descrip-
tion of flood damage history; description of potential flood damages; descrip-
tion of flood control work; short-term and long-term goals and objectives for
the planning area; fish resources; wildlife resources; scenic, aesthetic, and
histor 'ic resources; water quality; hydrology; and existing recreation. This
information is presented in Chapter 3 (general physical, biological, and socio-
economic data), Chapter 4 (geohydrologic and flooding information), Chapter 5
(flood damage characteristics and previous planning responses), and Chapter 6
(existing regulatory programs).

ANALYSIS OF INVENTORY
Information inventory and analysis was carried out in a series of "feed back
loops" -- initial analyses often indicated the need for additional information
in certain areas. Information analysis culminated in the identification, as
specifically as possible, of problem features and geographical areas.

PLAN DEVELOPMENT AND EVALUATION OF ALTERNATIVES
Plan development was carried out by evaluating approaches used for flood con-
trol management planning in the Skokomish Valley in the past, in other areas of
the state and nation, and by approaching the Skokomish Valley as an area with
certain unique problems. A review of alternative flood control management mea-
sures is presented in Chapter 7.

Alternatives were developed and defined in response to specific identified
problems in the Skokomish Valley and river basin. Certain alternatives which
have been proposed in the past and rejected for adverse cost - benefit reasons
were not included in the final articulation of alternatives. The selected al-
ternatives are described in Chapter 8.

PLAN SELECTION AND'IMPLEMENTATION
The purpose of this Skokomish River Comprehensive Flood Control Management Plan
is to provide Mason County officials and citizens with general information on
flood control management options as the basis for selecting specific alterna-
tives for detailed engineering, economic, and environmental evaluation This

CFCMP does not in and of itself provide the detailed engineering, economic, and
environmental analyses.

First, Mason County officials and citizens must choose the alternatives which
are socially, economically, and environmentally acceptable. Second, detailed
engineering and economic plans must be completed, along with environmental re-
view, probably including an environmental impact statement. Third, funding and
technical assistance must be acquired from local, state, and federal sources.
Fourth, the chosen alternatives must be implemented through construction con-
tracts, local self help programs, and delegation of administrative responsi-
bilities. Finally, a performance evaluation of the program should be completed
to assure that what was desired was actually put in place.

Chapter 3

SKOKOMISH RIVER WATERSHED CHARACTERISTICS

INTRODUCTION
The Skokomish River basin drains approximately 240 square miles of the south-
eastern portion of the Olympic Peninsula (Sorlie, 1975) into southern Hood Ca-
nal, an arm of the Puget Sound system (see Figure 3.1). Most of the basin is
forested, either as forest preserves in the Olympic National Park, or as man-
aged timber forests in the Olympic National Forest or on industrial timber
lands. Only in the Skokomish Valley, along the lower South Fork and the main-
stem of the Skokomish River, has there been any substantial conversion to other
land uses, primarily agriculture and rural residential. This chapter of the
report will discuss the existing conditions in the basin, and where necessary
provide an historical context for certain topics.

The primary study area for this CFCMP is the area which experiences the major-
ity of flood damage: the 17 square mile Skokomish Valley. For the purposes of
this report, the Skokomish Valley is defined as extending from the Skokomish
delta on Hood Canal upstream to the narrowing of the South Fork flood plain at
the Olympic National Forest boundary (South Fork River Mile (RM) 3.5). Also
included is the flood plain of Vance Creek. See Figure 3.2. The secondary
study area is the entire Skokomish River basin.

Comprehensive information about the Skokomish basin and the Skokomish Valley is
dated, scant and widely scattered. The only comprehensive information base was
assembled in the late 1960s as a part of the wider ranging Puget Sound and Ad-
jacent Waters (PSAW) Study conducted by the Pacific Northwest River Basins Com-
mission.

NATURAL SYSTEMS
The natural systems of the Skokomish basin -- climate, physiography, geology,
water resources, and ecology -- are fundamentally the result of post-glacial
conifer forest growth on steep slopes with a thin soil cover.

In this report stream names and numbers are in conformance with the Washington
Department of Fisheries system (Williams, Laramie, & Ames, 1975), and river
mile (RM) locations of features according to Ames & Bucknell (1981).

CLIMATE
The climate of the basin is generally typical of the Puget Sound region which
is strongly influenced by the Olympic Mountains which tend to shelter the basin
from the full effect of Pacific Ocean storm systems. The gap in the coast
ranges system between the Willapa Hills and the Olympic Mountains south of the
basin allows a limited measure of coastal storms to pass into the southern Sko-
komish basin and the Puget Sound basin in general (Molenaar & Cummans, 1973;
Phillips, 1968; Phillips & Donaldson, 1972). Precipitation, snow cover, and
evaporation, key factors in Skokomish Valley flooding, are discussed in Chapter
4.

Temperature: Temperatures vary throughout the basin due to topographic condi-
tions. The records kept at Cushman Dam are indicative of the conditions on the
plateaus adjacent to the Skokomish Valley. Typical of the 0 Puget Sound area,
the 8ighest temperatures occur in July (mean maximum, 78.3 F; mean T inimum,
47.8 F), and @he lowest temperatures in January (mean maximum, 83.17 F; msan
minimum, 30.5 F). The extremes recorded at Cushman Dam are 104 F and -2 F
(Phillips, 1986). No temperature data is known to exist for the Skokomish Val-
ley. Temperature has no direct effect on flooding, but does influence rainfall
- snowfall patterns which do affect flooding.

Wind: No meaningful wind information is available for the study area; the
closest monitoring stations within the Puget Sound basin are located in Olympia
(25 miles southeast), Tacoma (35 miles east), and Seattle.

In general, however, the prevailing winds are south to southwest during the
winter, and north to northwest during the summer. The strongest winds occur
during the winter when intense storms move inland from the Pacific Ocean. Ex-
treme wind velocities (at 30 feet above the surface) can be expected to exceed
55 m.p.h. once in 2 years; 80 m.p.h. once in 50 years; and 90 m.p.h. once in
100 years (Phillips, 1968). Wind patterns have no direct effect on flooding.

PHYSIOGRAPHY
The physiography or physical geography of the Skokomish basin is dominated by
the northwest - southeast trending ridge and canyon systems of the two main
forks of the river (North Fork and South Fork) and.the major tributaries (Le
Bar Creek and Vance Creek). For the most part, the minor tributaries form
northeast - southwest trending secondary ridge and canyon systems. A major
feature of the North Fork is Lake Cushman, a 4,000 acre, 8.4 mile long hydro-
power impoundment of the City of Tacoma (Ames & Bucknell, 1981; Bortleson, et
al., 1976; Williams, Laramie, & Ames, 1975). The physiography of the Skokomish
basin has no direct effect on flooding; however, the steep terrain is an impor-
tant factor in determining the location and existence of unstable river canyon
slopes which contribute to a high bed load and aggrading river bed, which di-
rectly result in an increasing frequency and severity of flooding.

Topography: With the exception of the Skokomish Valley and its adjacent pla-
teaus, the basin is typified by steep, rugged terrain (Williams, Laramie, &
Ames, 1975). The northwesterly limits of the basin run along the Olympic Moun-
tains watershed between the Pacific Ocean and Puget Sound at elevations of
4,000 to 6,000 feet. The lower basin is characterized by steep streamside
slopes and level to rolling plateaus. In the upper watershed, the valley walls
are steep and the ridge tops sharp. These slopes have been deeply dissected by
numerous small mountain streams. These streams discharge into the three prin-
cipal tributaries which flow through deep, narrow valleys and gorges to the
head of the Skokomish Valley near the confl.uence of the North Fork and South
Fork (Cowley, 1958).

The Skokomish Valley is generally characterized as flat, though it does still
exhibit the undulating topography common to the floodplains of the major Puget
Sound basin lowland rivers. Additionally, side channels to the present river-
bed remain from pre-settlement times. The valley, which is about 9 miles

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long, varies in width from 1/2 mile at its upper end to more than 2 miles at
the river mouth on Hood Canal,. The gradient of the valley is about -0.1% from
the delta front upstream to about RM 5; from RM 5 upstream to the North Fork
South Fork confluence, the gradient of the valley is about -0.2%.

A 1% gradient equals a 1 foot rise in 100 feet, normally considered the minimum
gradient for adequate drainage of engineered structures such as roadside
ditches and gutters. The gradient of the valley (and the river -- see the fol-
lowing paragraph) is substantially less than 1%, and thus has poor drainage
characteristics causing slow drainage of flood waters.

The gradient of the river in the primary study area is erratic (FEMA, 1983).
The gradient of the river is about +0.03% from the mouth (RM 0) upstream to RM
2, that is, the riverbed rises as the river itself flows downstream. Between
RM 2 and RM 2.6, 5- to 10-foot high sills have been deposited, probably as a
result of the interaction of tidal fluctuations and river discharge. Between
RM 2.6 and 4.8 the gradient is -0.14%, with sills up to 10 feet high occurring
between RM 4.8 and RM 5.5. ("Sills" in this context are abrupt rises in the
riverbed topography, with lower elevations both upstream and downstream of the
sill.) From RM 5.5 up to RM 8.6 just below the North Fork South Fork conflu-
ence, the gradients are: RM 5.5 to 7.2: -0.19%; RM 7.2 to 7.5: +0.27%; and RM
7.5 to 8.6: -0.33%.

Surface Drainage Patterns: The Skokomish River system is comprised of 9.0
miles of mainstem, 33.3 miles of North Fork, 27.5 miles of South Fork, and 270
miles of tributary streams. Vance Creek (11.0 miles) is the most important
tributary from a fisheries viewpoint; other important tributaries are Purdy,
Brown, LeBar, and McTaggert creeks (Williams, Laramie, & Ames, 1975). The
drainage patterns are mapped on Figure 3.1; the river mileage (RM) locations of
prominent features are listed in Table 3.1.

The Skokomish Valley is drained by a network of old meanders, creeks (Swift
Creek, Hunter Creek, Weaver Creek, and Purdy Creek; see Figure 3.2), and plowed
over sloughs. The sloughs, being partially filled, are clearly evident only
during low intensity flooding of the valley. The old meanders have been par-
tially filled, thus limiting their value in carrying flood flows, as well as
contributing to locally chronic high water tables and flooding. These issues
are discussed in greater detail in Chapter 4, Hydrology and Flooding.

Tidal7y Inf7uenced Area: Cummans (1974) determined the upper limit of tidal
influence to be "some point below RM 5.3" and that the "exact location of the
point was not asignificant factor" in his study of flood profiles of the lower
Skokomish River. This is not to say that tidal influence is not an important
factor in flooding of the Skokomish delta area, only that the exact location of
the upper limit of tidal influence is not a significant piece of information.

The average tidal levels at the tide gage at Union at the mouth of the Skoko-
mish River and the.corresponding land-based elevations are:
tidal elevation 1929 datum elevation
mean higher high water 11.8 4.9
mean high water 10.8 3.9
mean tide (sea) level 6.9 0.0

Table 3.1. RIVER MILE LOCATIONS OF PROMINENT RIVERINE FEATURES, SKOKOMISH BA-
SIN, WASHINGTON. (1)
------ ------ -----
Stream Stream River
Number(2) Name Feature Mile
-------------------------------------------------------------------------------
0001 Skokomish River mouth 0.0
SR 106 highway bridge 2.2
Purdy Creek (16-0005) 4.1
US 101 highway bridge;gaging 5.3
station 12-0615
powerline; former gaging station 6.0
12-0615; water quality station
16AO70
North Fork - South Fork confluence 9.0

0001 Skokomish River
continues as the
North Fork confluence with South Fork 9.0
gaging station 12-0595 10.0
McTaggert Creek (16-0105) 13.3
Lower Cushman Dam 17.3
(Lower Lake Cushman,
aka Lake Kokanee)
Lake Cushman Dam 19.6
Olympic National Forest boundary 24.0
Lake Cushman inlet 28.0
Olympic National Park boundary 28.1
Mason-Jefferson county boundary 37.9
headwaters 41.9

0011 South Fork mouth = confluence with North Fork 0.0
Vance Creek (16-0013) 0.8
gaging station 12-0605 3.1
Olympic National Forest boundary 3.5
forest 2202 road bridge 6.8
Brown Creek (16-0047) 12.8
LeBar Creek (16-0053) 13.5
Olympic National Park boundary 26.4
Mason - Jefferson county boundary 27.0
headwaters 27.5

-------------------------------------------------------------------------------
1. Sources: Ames & Bucknell, 1981; Fleskes & O'Connor, 1980; Williams,
Laramie, & Ames, 1975.
2. Stream numbers are 6-digit numbers, e.g. 12-3456, the first 2 digits
indicating the basin number and the remainder representing the specific
stream within the basin; Skokomish basin streams are numbered 16.0000,
etc.
3. The head of tidal influence is taken as mean annual high tide at low
instream flow.

Therefore, under average conditions (mean high water), direct tidal influence
will extend up the Skokomish River to the location where the river bed eleva-
tion equals 3.9 feet, and under extreme conditions (mean higher high water) to
the point where the river bed elevation equals 4.9 feet. Based on river bed
profiles according to FEMA (1983), these locations are RM 3.7 and RM 3.8 re-
spectively. Indirect tidal influence will occur above this location to a vari-
.able extent dependent on river flow volumes.,

No information is known to exist regarding the upper limits of salt water in-
fluence in' the delta. Salt water influence has no known effect on flooding in
the Skokomish Valley.

GEOLOGY
Typical of most of the Puget Sound region, the lower elevations of the Skoko-
mish basin are strongly influenced by geologically recent glacial advances and
retreats. The plateaus adjacent to the Skokomish Valley which rise 400 to 600
feet above the valley floor are composed of layers (lenses) of glacial outwash
sands and gravels and interglacial sediments (Molenaar & Noble, 1970). These
geologic strata are well exposed in the valley's canyon walls, perhaps best un-
der the power transmission line on the north side of the valley. In the upper
portions of the basin basalt bedrock is exposed in many locations, and the can-
yon reaches of the North Fork and South Fork have cut down to bedrock.

Geo7ogic Hazards: The canyon slopes edging the Skokomish Valley are classified
as potentially unstable except for the right bank slopes below RM 3; for the
most part this is of little or no direct consequence with respect to flood con-
trol management except where the river cuts close against a potentially un-
stable canyon slope (Smith & Carson, 1977). At these locations land management
and land development practices could result in slope failures which partially
block the river. Most slope failures occur during periods of heavy winter
rainfall (Canning, 1985), a time of the year which coincides with peak river
flows and flood events. There are four locations where the main stem flows
close, against a potentially unstable slope.

The first is along the right bank in the vicinity of RM 1 where a Class 2 slope
rises from the flood plain to the plateau top. Class 2 slopes are defined as
stable under normal conditions, but which may become unstable if disturbed by
manis activities, by oversteepening, or by seismic shaking (Smith & Carson,
1977). Here the slopes are buffered from the river by SR 106.

The second is along the right bank between RM 2.9 and 3.7 where a Class 3 slope
rises from the flood plain part of the way up the slope and is surrounded by
Class 2 slopes. Class 3 slopes are defined as areas inferred to be unstable
because they are underlain by weak, unstable materials with a history of
landsliding (Smith & Carson, 1977). Here too, the slopes are buffered from the
river by SR 106. (Slope Class is a means of categorizing land into generalized
levels of stability or instability ranging from Class 1 -- most stable -- to
Class 5 -- least stable.)

The third is along the left bank between RM 5.8 and 6.1 in the vicinity of a
power transmission line where Class 3, 4, and 5 slopes rise to the plateau top.
Class 4 slopes are defined as former landslide areas, including relatively

large slumps, flows, and slides of soil, rock, and debris, which may be reacti-
vated by excavations, slope modifications, or seismic shaking. Class 5 slopes
are defined as known areas of recently active slope failures, usually within
the past 50 years (Smith & Carson, 1977). Here, Sunnyside Road has been
benched into the canyon slope and the river flows against the base of the can-
yon slope.

The fourth is along the left bank between RM 7.6 and 7.7 in the vicinity of the
confluence of Stream 16-0008 where a Class 4 slope extends part way up the
slope (Smith & Carson, 1977). Here the river flows against the canyon slopes.

The locations of these geologic hazard areas are delineated on oblique aerial
photographs of the Skokomish Valley in Appendix B.

Geologic hazard areas are not known to be mapped for other areas of the basin,
but observations of Class 5 slopes made by the authors of this report during
aerial reconnaissance flights over the South Fork basin indicate that unstable
slopes are common in that area also. Some of these recent slope failures in
the South Fork Valley (RM 7 to RM 24) have resulted in landsliding directly
into the South Fork, and are suspected of being the major contributor to the
high bed load and river bed aggradation problems in the main stem. River bed
aggradation is discussed in Chapter 4.

Minerals: Few mineral deposits are known from the Skokomish basin. No oil or
gas exploration has occurred in the Skokomish basin (McFarland, 1983). The
mid- to upper portion of the basin lies within the Olympic Peninsula limestone
belt, but there has been no commercial development. The lower portion of the
basin lies within a zone of sand and gravel deposits, but there has been no
commercial development in the basin. No other nonmetallic minerals are known
from the basin (Valentine & Huntting, 1960)., Copper and manganese (and associ-
ated metallic minerals such as iron and zinc) are known from the North Fork ba-
sin, particularly from the ridges along the divide to the Hamma Hamma basin,
but there has been no commercial development (Huntting, 1956). The Washington
Department of Game has issued a number of HPAs (Hydraulic Project Approvals)
for instream gold mining in the main stem; no information is known to be avail-
able on production. This level of minerals exploration and exploitation does
not appear to have any effect on flood characteristics.

There are no known studies of the sand and gravel resource in the Skokomish ba-
sin or river system, or of sand and gravel transport. Bell (1982) reviewed
sand and gravel transport and the potential effects of the then proposed South
Fork hydropower dam in a theoretical context, but conducted no substantive
field studies or observations. Anecdotal reports received from a number of re-
source agency staff indicate that the Skokomish River carries a relatively high
bed load of sand and gravel. This is discussed in Chapter 4.

Soi7s: The soils of the Skokomish River basin are typical of the mountainous
soils of the east slope of the Olympic Peninsula. These soils are character-
ized as having a high erosion potential that is related to slope steepness and
high rainfall rates. These soils are easily disturbed by man's activities such
as road building and other earth moving activities, or devegetation during
clearcut logging. Soils on forest slopes are relatively shallow; soils on the

plateaus are deeper. In general, the upland soils on slopes are well drained,
with low to moderate water retention, and high infiltration rates. (ONF,
1986b; Rushton, 1985.)

A recent review of the cumulative effects of forest practices (Geppert, et al.,
1984) concluded that:

Forest roads and timber harvest are practices that cause the greatest
disturbance to the soil. Both accelerate surface erosion and in-
crease the frequency of debris avalanches. Increased erosion de-
creases water quality and degrades aquatic habitat. These forest
practices also alter the hydrologic cycle affecting the timing and
volume of runoff. Because of the permanency of forest roads, the
persistence of associated erosion processes, and the continual nature
of timber harvest, we conclude that persistent cumulative effects on
erosion, water quality and quantity, and aquatic habitat and associ-
ated aquatic fauna will result. The magnitude of these cumulative
effects are site specific and depend on the amount of road involved,
the intensity of harvest activities, the resiliency of the individual
sites, and the scheduling of activities. We also believe, as did
many people interviewed, that environmental changes caused by con-
struction, use, and maintenance of forest roads constitute the great-
est contribution to these cumulative effects, especially to persis-
tent alterations of aquatic habitat (substrate and clarity).

Forest road construction, use, and maintenance increase stream sedimentation by
two processes: (1) by increasing the incidence of mass failures (e.g. land
sliding and debris sliding); and (2) by erosion of the road surface, cut and
fill slopes, roadside ditches, and uncompacted sidecast excess cut material,
and the transport of this material to streams. In areas with steep slopes and
unstable soils, landslides are the source of mo'st road-derived sediment deliv-
ered to streams; in more stable landscapes, material eroded from road surfaces
and associated areas can predominate (Duncan, et al., 1987; Megahan & Kidd,
1972)..

The South Fork basin subject to intensive logging has from 4 to over 5 miles of
road per square mile (average: 4.5), a rela,tively high level of forest road
construction.

Soil erosion indices for the Skokomish basin portion of the Shelton CYSU devel-
oped by the US Forest Service (ONF, 1986b) indicate a potential sediment yield
of about 320,000 CY/D (cubic yards per decade) during the past two or three de-
cades (Figure IV-6). Natural sediment production is estimated to be 90,000
CY/D, thus man's activities, principally forest practices, could have resulted
in the generation of about 230,000 CY/D of sediment to the Skokomish River.
Most of this erosion would have occurred in the South Fork basin as relatively
little logging occurs in the North Fork basin. Additionally, any sediment pro-
duced in the upper North Fork basin would be deposited in Cushman Reservoir.

These US Forest Service soil erosion estimates are based on a predictive model
requiring that assumptions be made. The model has not been calibrated with
field measurements. Regarding sediment yield, the model assumes that within
200 feet of a stream, approximately 90% of eroded soil is delivered to the
stream, and that from sites further removed from a stream, approximately 60% of

eroded soil is delivered to the stream. Furthermore, the model used cannot
provide actual amounts of erosion and sediment yield to a stream, only relative
amounts for purposes of comparing past and alternative future land use prac-
tices. Thus the estimated natural sediment production (90,000 CY/D) and poten-
tial sediment yield (320,000 CY/D) may not be accurate, but the relative rela-
tionship 3.6 times as much sediment yield due to erosion caused by forest
practices is probably accurate.

Confirmation of the US Forest Service soil erosion model estimate is suggested
by a US army Corps of Engineers study of erosion and sedimentation in the Grays
Harbor Estuary basin (Kehoe, 1982). Kehoe consolidated and summarized research
on erosion rates in the Chehalis River basin, and found that the middle and
west forks of the Satsop River and Wynoochee River basins draining the south-
erly portions of the Shelton CYSU had sediment discharge rates 3 to 5 times the
rate from basins not subject to intensive logging. Sediment discharge from the
Satsop and Wynoochee basins ranged from 1,100 to 1,500 tons/square mile/year,
compared with sediment discharge rates elsewhere in the Chehalis basin of less
than 100 to 300 tons/square mile/year.

The Shelton CYSU and Skokomish basin is characterized by unstable soils and
steep slopes, thus land sliding and debris sliding can also be expected to con
tribute sediments to the river system. These materials, along with natural
landslide events, all contribute to river bed aggradation.

The soils of the primary study area, the Skokomish Valley, are deep alluvial
soils, many of which have relatively high agricultural Capability Class ratings
and substantial limitations for development as summarized in Table 3.2 (Ness &
Fowler, 1960). Alluvial soils, deposited by successive flooding of river val-
leys, typically have high agricultural values because of their widespread
sources across the landscape. Because of their widespread sources, alluvial
soils contain a variety and abundance of minerals necessary for plant growth
not commonly found in soils which have developed in place from a single parent
rock source. Thus the flooding of the Skokomish Valley is the source of its
agricultural productivity.

The development limitations are created by a high ground water table in the al-
luvial soils and include: (1) sewage disposal leach field performance impaired
throughout the year and prevented seasonally during high water periods; (2)
soil load bearing strength for building foundations and roadways is reduced.
High water tables are a natural occurrence in river valley flood plains. Ex-
treme high water tables at the ground surface are a temporary, natural effect
of flooding.

WATER RESOURCES
The water resources of the Skokomish basin are important for their contribu-
tions to groundwater recharge, fish and wildlife habitat, recreational opportu-
nities, hydropower production, and a small amount of irrigation in the Skoko-
mish Valley.

Groundwater: The groundwater of the Skokomish 'basin has not been studied in
detail due a lack of need for this information.

Table 3.2. SOILS CHARACTERISTICS, SKOKOMISH VALLEY, MASON COUNTY, WASHINGTON.

-------------------------------------------------------------------------------
Soil Type Capability Development
Code Name Class Limitations

-------------------------------------------------------------------------------
Skokomish Val7ey above US 101
Dg Dungeness fine IIW The Dungeness series has severe
sandy loam limitations for on-site sewage
Dh Dungeness fsl, IIW disposal and building construction due
shallow to flooding and wetness; from November
Dk Dungeness silt IIW through April the depth to the water
loam table is 2 to 4 feet and less when
flooding occurs.

Pa Pilchuck gravelly VIIs The Pilchuck series has severe
loamy sand limitations for on-site sewage
Pb Pilchuck loamy VIS disposal- and building construction due
sand to flooding and wetness; from November
Pc Pilchuck sand, VIIS through April the depth to the water
shallow table is 2 to 4 feet and less when
flooding occurs.

Ra Riverwash VIII Riverwash is considered unsuitable
for any development due to its
proximity to the river and frequency
Skokomish De7ta below US 101 of flooding.
Dg Dungeness fine IIW See notes on Dungeness series above.
sandy loam
Dk Dungeness silt IIW
loam

Mg Mukilteo peat IIIW The Mukilteo series has severe
Mh Mukilteo peat, IVw limitations for on-site sewage
shallow over gravel disposal and building construction due
to wetness and low strength; from
October through May the depth to the
water table is 1.5 to 3 feet and
less during flooding.
Pd Puget silt loam' IIIW The Puget and Skokomish soils have
Sr Skokomish silt loam IIw the same severe limitations as the
Dungeness and Pilchuck soils as
described above.

-------------------------------------------------------------------------------
Source: Ness & Fowler, 1960; US Soil Conservation Service Soil Interpretation
Record sheets for Mason County.

The ground water of the Skokomish Valley was evaluated incidental to a general
study of groundwater in southeast Mason County (Molenaar & Noble, 1970). At
that time, dug and driven wells 9 to 22 feet deep were commonly in use.
Drilled wells were generally in the range of 20 to 45 feet deep. Because these
wells were used for single family domestic use and stock watering, only small
capacity pumps had been installed, and the full potential of the wells had not
been determined.

The water table varies seasonally, and during the winter rises to within 1.5 to
four feet of the surface (see Table 3.2) and higher during periods of heavy
rainfall or flooding. These data are probably conservative, that is, the win
ter water table is likely higher. One local resident reports that the water
table under the Valley between highway US 101 and the North Fork - South Fork
confluence area appears to be higher now than in the 1950s based on the current
abundance of "swamp grass" -- Juncus effusus -- in the fields and pastures com-
pared with the 1950s when the plant was uncommon in the Valley. Juncus
effusus, Soft Rush, is a common indicator of wet meadows and wet pastures in
the Pacific Northwest. Soft Rush can be very common in wet pastures because it
resists trampling by cattle and is not palatable (Boule, et al., 1985).

Based on this evidence, it is likely that the winter water table has risen in
recent decades, but there is no direct evidence. The appearance of Soft Rush
could be due to a rising water table or could be due to less intensive agricul-
tural practices. As discussed in the Land Use section of this chapter,
dairying was once a widespread practice in the valley, and many former dairy
farm fields now lie idle.

On the Skokomish Indian Reservation, Tribal staff and council members report an
increase in ground water levels adjacent to the old river meanders in Section
14, T21N, R4W. Here, the increase in the water table is apparently solely due
to the filling of the outlet of the southerly meander into the main stem (RM
4.1), thus causin'g a chronic, localized high water table. In low lying areas
the water table is above the ground surface and has converted former farm
fields to wetlands.

Surface Water: The surface water resources of the Skokomish basin have been
reviewed recently by the Water Resources Program, Washington Department of
Ecology, in the context of the entire Water Resource Inventory Area (WRIA) Ba-
sin 16 (Rushton, 1985). WRIA 16 also includes the Hamma Hamma River, Duckabush
River, Dosewallips River, and a number of small, independent drainages to the
north of the Skokomish basin.

Surface water runoff volumes from the Skokomish basin are typical of the runoff
rates (cubic feet second/square mile; cfs/sq mi) of other river systems drain-
ing the eastern slopes of the Olympic Peninsula (see Table 3.3), but are ap-
proximately double the typical runoff rates of river systems elsewhere in the
Puget Sound basin. These higher runoff rates are attributable to the greater
annual rainfall in the eastern Olympic river basins.

Average discharge volumes in the main stem as measured at the gage at RM 5.3
are highly variable. Mean minimum discharges range from approximately 160 cfs
(cubic feet per second) during July through October, to 750 to 1,000 cfs during
December through March. Mean monthly discharges range from approximately 300

Table 3.3. COMPARISONS OF RUNOFF FROM SELECTED PUGET SOUND RIVER BASINS.

-------------------------------------------------------------------------------
River Basin Mean Annual Drainage Area, cfs/
Runoff, cfs square miles square mile
-------------------------------------------------------------------------------
North Olympic Peninsula Basins:
Elwha 1510 319 4.73
Dungeness 380 203 1.87

East Olympic Peninsula Basins:
Duckabush 470 77 6.10
-Dosewallips 610 120 5.08
Hamma Hamma 560 85 6.59
Skokomish 1245 240 5.19

South Puget Sound:
Deschutes 410 160 2.50
Nisqually 2070 716 2.92
Puyallup 3350 948 3.53

-------- ---- --- ----
Source: Sorlie, 1975.

cfs during July through September, to approximately 2,150 during December
through February. Mean maximum flows range from approximately 400 cfs during
August, to 4,500 to 5,500 cfs during December and January (Richardson, 1974).
Peak flows have occurred as summarized in Table 3.4. River hydrology is dis-
cussed in greater detail in Chapter 4.

On the North Fork, two impoundments constructed by Tacoma City Light, Cushman
Reservoir and Lower Cushman Reservoir, provide hydropower to the City of Tacoma
and its nearby service area. Cushman Dam was completed in 1.926, enlarging a
natural lake in the North Fork to a reservoir with a surface area of 4,000
acres and volume of 453,000 acre-feet. Lower Cushman Dam was completed in 1930
creating an impoundment covering 475 acres with a volume of 8,000 acre-feet
(Bortleson et al., 1976; TCL, 1985). Virtually the entire discharge of the
North Fork basin is diverted in a tunnel directly to the Tacoma City Light pow-
erhouse on Hood Canal. The remnant flows in the North Fork contributing to
main stem flow are derived from storm runoff freshets, spillage over the dam
during winter high water - high runoff conditions, and diversions from the tun-
nel system for maintenance and debris removal purposes (Williams, et al.,
1975). The direct effect on main stem flooding of the diversion of North Fork
Flows was to reduce main stem flood flow volumes. The indirect effect has been
a decrease in overall flow volumes leading to a decreased capacity to move bed-
load through the system, further contributing to river bed aggradation.

WATER QUALITY
The Skokomish River and its tributaries are classified as Class AA waters (WAC
173-201-080 [93]) for the establishment of water quality standards. Class AA
water quality standards are summarized in Table 3.5.

Table 3.4. SELECTED PEAK FLOWS, MAIN STEM, SKOKOMISH RIVER.
-------------------------------------------------------------------------------
Date Discharge, cfs Recurrence interval, years
-------------------------------------------------------------------------------
3 November 1955 27,000 30 (highest recorded streamflow)
20 January 1972 18,500 4
5 March 1972 19,700 5.3

- ----- ---- ------ ---
Sources: Cummans, 1974; FEMA, 1987; Molenaar & Cummans, 1973.

Table 3.5. CLASS AA WATER QUALITY STANDARDS, WASHINGTON. (1)

----- ---- ----- -- ----- ------- ---------- ----------- ---
Parameter Units Standard

----- --------- ------------- -- ---- - ------ ---
Fecal coliforms organisms/100 ml mean <50/100 ml;
(FC) < 10% of samples > 100/100 ml

.Dissolved oxygen milligrams/liter > 9.5 mg/l
(DO) (parts per million)

Total dissolved percent of < 110 percent,
gas saturation
Temperature degrees Celsius < 16 oc2

Hydrogen ion pH units pH 6.5 to 8.5

Turbidity NTU units < 5 NTU over background (2)

Toxics not applicable no effect on public health (2)

Aesthetics not applicable no impairment (2)
-------------------------------------------------------------------------------
1. Source: WAC 173-201-045 (1).
2. See WAC 173-201-045 (1) for details or special conditions.

In October 1983, the Department of Ecology established a water quality monitor-
ing station (number 16AO70) at the USGS stream gage at RM 6.0 on the main stem.
The data from that monitoring station (available through September 1986) is
summarized as follows.

Fecal coliform (FC) concentrations are generally in the range of 1/100 ml
to 20/100 ml, with three extremes of 22, 29, and 53/100 ml. The FC data
shows no seasonal or any other correlation. These values consistently
meet the Class AA water quality standards.

Dissolved oxygen (DO) concentrations are highest during the winter, ap-
proximately 12 mg/l from January through March, and lowest during the sum-

mer, usually 9.6 mg/l or greater during August and September. Only once,
in August 1984, was DO below the minimum value when a concentration of 9.0
mg/l was recorded. These levels meet the Class AA water quality stan-
dards.

Total dissolved gas is not monitored on the Skokomish River. This param-
eter is important principally at plunge pools at the base of major dams,
and thus is of little concern on the Skokomish.
Temperatures range from 9 to 110C during June through August, to 5 to 6 0C
during December through March. These values consistently meet the Class
AA water quality standards.

Hydrogen ion (pH) values range between 6.7 and 7.8 pH units with no appar-
ent seasonal correlation or correlation with any other factor. These val-
ues consistently meet the Class AA water quality standards.

Turbidity levels are closely correlated wit h river flow volumes. At flow
volumes of less than about 1,500 cfs, normal background turbidity is in
the range of 1 to 10 mg/1 suspended solids and 1 to 5 NTU turbidity units.
At flow volumes of 1,500 cfs to 5,000 cfs, there appears to be a straight
line relationship between flow volume and suspended solids, with suspended
solids concentrations increasing from about 10 mg/l (5 to 7 NTU) at 1,500
cfs, to 50 mg/l*(26 NTU) at 5,000 cfs. Above 5,000 cfs, the suspended
solids loading becomes highly variable, ranging up to 260 mg/l (83 NTU) at
9,320 cfs and 360 mg/l (190 NTU) at 6,560 cfs. These data are not suf-
ficient to determine whether these patterns represent normal background
conditions for these flow volumes, or whether they represent violations of
the Class AA standards due to logging practices on Olympic National Forest
lands upstream.

In general, water quality in the main stem may be assumed to be in compliance
with Class AA standards. Additional investigations or data evaluations would
be necessary to confirm this assumption with respect to turbidity and suspended
solids.

Water quality analyses performed in the Skokomish River system suggest that all
water quality parameters affecting salmonids are within acceptable levels. In
the lower North Fork, however, the greatly reduced flow volumes resulting from
diversions by Tacoma City Light at Cushman Dam reduce the ranges of available
water velocity and depths; the reduced water volumes are more subject to the
warming influence of ambient air temperatures (Wampler, 1980). Spot checks of
the North Fork below the Tacoma City Light diversions have shown elevated tem-
peratures (Kendra, 1985).

ECOLOGY
The Skokomish basin lies within the greater Puget Sound basin. The Skokomish
headwaters lie within the Picea sitchensis (Sitka Spruce) forest ecosystem,
with the remainder of the basin within the Puget Sound Tsuga heterophylla
(Western Hemlock) forest ecosystem (Franklin & Dyrness, 1973). Thus, with mi-
nor exceptions, the basin is covered by various types of conifer forests. The
largest exception is the primary study area, the Skokomish Valley, which in its
pre-settlement state was a riparian floodway dominated by a mix of Western

Redcedar and various broadleaf trees.

Presently, much of the South Fork basin lies within the Shelton Cooperative
Sustained Yield Unit (Shelton CSYU) of the Olympic National Forest and adjacent
industrial timber lands of Simpson Timber Company. The Olympic National Forest
portion of the Shelton CSYU has been extensively clear-cut and roaded in recent
decades, leaving the forest in early successional stages. The South Fork basin
within the Shelton CSYU appears to be about 80% clearcut based on visual esti-
mates obtained during reconnaissance flights over the area. The intensity of
timber harvest in the Shelton CYSU has provoked a great measure of controversy
regarding potential adverse effects on fisheries, water quality, and flooding.
The Skokomish Indian Tribe initiated a lawsuit against the Olympic National
Forest in 1982 which was not carried to completion because the Tribe lacked the
necessary financial resources. The issue remains unresolved.

In contrast, much of the North Fork basin lies within the Olympic National
Park. Here the forest is in mature and old growth successional stages. The
lower North Fork basin was logged many decades ago, and is now mostly in
relatively mature second growth successional stages of development.

Skokomish Val7ey: The Skokomish Valley has been extensively converted to agri-
culture through the cutting and removal of the aboriginal riparian forests.
The US Government Land Office (GLO) surveyor's field notes for the subdivision
of the Skokomish Valley into townships and sections during the summer of 1861
indicate a flood plain forest, swampy and impassible in places, and cut by nu-
merous sloughs which drained the valley into the river. The witness trees to
the section and quarter-section corners are indicative of a frequently inun-
dated flood plain: Vine Maples, 4 to 8" diameter; alders, 6 to 20"; crabapples ,
5 to 16"; willows, 6 to 84"; cedars 30 to 36"; maples, 18 to 36"; plus an oc-
casional dogwood, hazel, and hardhack. The frequency with which a short lived
species like Vine Maple was selected as witness trees to the section corner
monuments is indicative of a valley floor with abundant, dense brush and
relatively few trees.

Today, most of the valley has been converted to pasture and Christmas tree
plantations. The riparian forests which remain are mostly younger, second
growth stands on gravel bars, low lying areas, and less desirable soils.

Skokomish Estuary: An ecological and resource characterization of the Skoko-
mish Estuary was developed by Canning and Shea (1979) as follows. The salt
marshes at the mouths of the Skokomish River are mapped as a "major salt marsh
(Martinson, 1976) of Hood Canal. The intertidal mud flats of the Skokomish
delta cover at least 1,500 acres on the east side of Annas Bay, constituting
one of the largest intertidal flats on Hood Canal. Annas Bay is classified as
a "major waterfowl area" and supports large beds of eelgrass (Division of Ma-
rine Land Management, 1977). The Skokomish delta is the location of the larg-
est single Harbor Seal haul-out site in Puget Sound. The peak seal count in
1977 was 342 adults and pups, 5% of the Washington state population and 15% of
the Puget Sound population (Calambokidis et al., 1978). The Annas Bay - Skoko-
mish Estuary system has been recommended for preservation as a wetland of par-
ticular significance (Yoshinaka & Ellifret, 1974).

Historical changes in the character and extent of the Skokomish delta between

1884 and the late 1970s were studied by Bortleson, Chrzastowski, & Helgerson
(1980). They noted minor changes in the shoreline near the mouths of the river
where some shorelines had eroded (recession), and some had builtup (prograda-
tion), with the shifts about equal. They also noted that the delta intertidal
mud flats in Annas Bay had decreased by about 0.5 sq km (0.2 sq mile).

FISHERIES
The most complete and accurate source of information on the salmon fishery re-
source of the Skokomish basin is still the Washington Department of Fisheries''
stream catalog (Williams, Laramie, & Ames, 1975) (Whittier Johnson, WDOF, per-
sonal communication). Relatively little is known about the resident fish (e.g.
non-anadromous fish) of the basin as no studies of resident fish have been car-
ried out. The principal fisheries issues are water quality (e.g. dissolved
oxygen and temperature), instream habitat (e.g. gravel quality and riffle -
pool patterns), and streamside habitat (e.g. canopy coverage shading and buff-
ers).

Anadromous Fish: Anadromous fish produced in the Skokomish River system and
its tributaries support important commercial and recreational fisheries in Hood
Canal, the Strait of Juan de Fuca, and the river itself. At one time the Sko-
komish River system produced substantially larger runs of salmon than in recent
years (CH2M Hill, 1983; Findlay, 1973; Williams, et al., 1975). Cushman Dam
greatly reduced anadromous fish habitat on the North Fork system by creating a
barrier to historical spawning grounds and degrading habitat below the dam by
diverting flows (Wampler, 1980). However, the project developer, Tacoma City
Light, has partially mitigated the fish loss by construction of the George
Adams Fish Hatchery on Purdy Creek (Rushton, 1985) which is operated by the De-
partment of Fisheries. This report will concentrate on the fisheries of the
primary study area, the Skokomish Valley.

Within the primary study area, the main stem, lower South Fork, and Vance Creek
provide spawning and rearing habitat for Chinook, Chum, Coho, Pink, and Sockeye
salmon, and Steelhead and Cutthroat Trout; this portion of the basin is.par-
ticularly important to Chinook, Coho, and Chum production. A small upriver run
of Spring Chinook passes through the Skokomish Valley, and matures in the
deeper pools of the canyon reach of the South Fork during summer months. The
major Skokomish run of Fall Chinook enters the river in September and October
and spawns in the main stem, the South Fork, and occasionally in Vance Creek.
All accessible tributaries contribute to Coho production. Chum Salmon spawning
occurs in the main stem and the tributaries, with heaviest utilization being in
Richert Springs, Vance Creek, and Swift Creek. Typical spawning populations in
the early 1970s were 600 Chinook and 1,800 Chum (Williams, et al., 1975).

In recent years, the South Fork spawning populations have,been about 100 Chum,
100 Coho, 506 Fall Chinook, 60 Spring Chinook, and a few hundred Winter Steel-
head and some Summer Steelhead. The South Fork tributary, Vance Creek spawning
populations have been about 1,100 Chum and 500 Coho. The Pink Salmon run has
essentially disappeared from the South Fork apparently as a result of the large
Chinook and Coho releases from George Adams Hatchery on the lower main stem.
The larger Chinook and Coho juveniles are thought to feed heavily on the mi-
grating Pink fry (Caldwell, 1984).

North Fork spawning populations have been about 3,500 Chum, 2,200 Coho, 25 Fall
Chinook, and some Steelhead (Caldwell, 1984).

Mainstem spawning populations have been about 250 Chum, 500 Coho, 800 Fall Chi-
nook, and a few hundred Winter Steelhead and some Summer Steelhead (Caldwell,
1984).
Limiting factors in the primary study area include summer low flows which limit
the availability of rearing areas, and excessive winter high flows which
intensify the problems associated with unstable streambed gravels (Williams, et
al., 1975). Additionally, recreational misuse of the river is a localized
problem where recreational vehicle (RV) operators drive in and through the
river, damaging salmon eggs in the gravel. Fisheries and game enforcement
agents report frequent motorized travel on the riverbed across salmon spawning
redds which can compact the gravel and grind the salmon eggs within the gravel.

The locations of prime spawning gravels is not currently documented. The in-
stability of the gravel bed of the river, the shifting pattern of the riverbed ,
and the riverbed aggradation produce annual changes in spawning gravel loca-
tions.

The Washington Department of Fisheries operates the George Adams Hatchery on
Purdy Creek, a tributary to the mainstem. This hatchery was constructed in co-
operation with the City of Tacoma to mitigate for fisheries losses caused by
the construction of Cushman Dam on the North Fork (Williams, Laramie, & Ames,
1975). The production of the hatchery (see Table 3.6) is released principally
into Purdy Creek, and also into other streams in Mason, Thurston, Kitsap, and
Jefferson counties (Abrahamson, 1986).

Resident Fish: No substantive information is known to exist regarding resident
fish (e.g. Rainbow Trout, nonmigratory Cutthroat Trout, and nongame species)
anywhere in the basin. 'This is not an unusual situation; resident fish are not
the economic resource that anadromous salmon are, thus detailed studies are
rarely carried out.

The Washington Department of Game has operated the Shelton Trout Hatchery on
Swift Creek at Mohrweis since 1946. A variety of freshwater species are raised
at the hatchery for release throughout western Washington. A small amount of
the Shelton Trout Hatchery's production is released into the Skokomish River
system.

Forecast: Salmon enhancement is proposed within the Skokomish basin under the
Washington Department of Fisheries' Watershed Planning Program. Under the Hood
Canal Salmon Management Plan, depleted Spring Chinook stocks would be rebuilt
as the first step in the development of an overall strategy for fisheries man-
agement in the Skokomish basin. Other strategies proposed include the improve
ment of river flows, and the restoration and protection of Spring Chinook
spawning and rearing habitats (WDOF, 1987). The Point No Point Treaty Council,
in conjunction with US - Canada Treaty studies, is conducting a Skokomish River
Coho Indicator Stock Study. The Treaty Council also releases Chinook Salmon in
the basin as a.part of an enhancement program.

Table 3.6. SALMON RELEASES FROM GEORGE ADAMS HATCHERY, PURDY CREEK, SKOKOMISH
BASIN, WASHINGTON, 1982 1986

------ ----------- ---- - -----
Salmon Species
Year --------------------------------------------- Total
Fall Chinook Coho Chum

-------------------------------------------------------------------------------
1982 2,541,697 2,170,365 - 4,712,062
1983 3,161,200 2,260,874 16,847,700 22,269,774
1984 3,704,600 614,400 7,967,000 12,286,000
1985 4,703,400 915,900 24,772,300 30,391,600
1986 data not yet published
Sources:-Abrahamson,-1986;-Castoldi,-1983;-Hill,-1984;-Kirby,-1985 -------------

Flood control or management works could adversely affect fisheries habitat and
productiod by impairment or destruction of spawning gravels and streamside veg-
etation. Questions remain regarding the effect of river aggradation and spawn-
ing gravel.

WILDLIFE
There are no recent, comprehensive studies or reports describing the wildlife
of the Skokomish basin or the Skokomish Valley. This situation is typical of
most areas of the state and is not indicative of low wildlife values in the
area not worth monitoring.

A characterization of 'the Skokomish basin's wildlife and habitats was developed
during the late 1960s as a part of the PSAW Study (Fish and Wildlife Technical
Committee, 1970). The Skokomish basin was lumped with other east Olympic Pen-
insula basins and the Kitsap Peninsula basins as the "West Sound Basins," thus
information specific to the Skokomish is blurred with reference to all the West
Sound Basins. Information on the Skokomish basin is summarized as follows.
Due to the lack of development in the area, the description is probably still
accurate. Elk are found in "mediUm to high" population densities throughout
the upper elevations of the South Fork basin and the mid elevations of the
North Fork basin above Cushman Reservoir, and may be found throughout the en-
tire basin except for the Skokomish Valley and the adjacent plateaus to the
north. Deer are distributed throughout the basin, and concentrated in area be-
tween the South Fork and North Fork from the confluence area north to Cushman
Reservoir. Waterfowl are distributed throughout the easterly half of the ba-
sin, and particularly in the Skokomish Valley which was identified as an impor-
tant wintering area.

No wildlife population or habitat studies are known to have been conducted in
the Skokomish Valley. Most native habitat has been converted to farm fields,
and in recent years, to Christmas tree plantations; these agricultural land
uses have relatively little wildlife habitat value. The remnant riparian for-
ests and forested wetlands of the valley probably provide habitat for deer;
small terrestrial mammals such as raccoon, chipmunks, mountain beaver*, mice,
and voles; and aquatic mammals such as muskrat, beaver*, and river otter. Sea-

sonally, the forests provide habitat for migrating and nesting song birds. The
ponds and drainages of the valley provide-wintering habitat for waterfowl such
as mallard* and other dabbling ducks, and diving ducks such as bufflehead*.
Resident species such as Great Blue Heron* can be expected to be locally com-
mon; during the late winter Bald Eagle* commonly feed along the river from
perches in riverbank trees. The farm fields provide habitat for starling*,
blackbirds*, and crow*. (Sightings or evidence of specific species indicated
by an asterisk* in text.)

Flood control or management works could adversely affect wildlife habitat'and
production by impairment or destruction of streamside vegetation.

SPECIAL PLANTS, ANIMALS, AND ECOLOGICAL COMMUNITIES
Endangered, threatened, and sensitive plant and animal species and high quality
native plant (ecological) communities may be found throughout the Skokomish ba-
sin. This section will address only the primary study area, the Skokomish Val-
ley. The known occurrences of special plants, animals, and ecological communi-
ties are summarized in Table 3.7 from information provided by the Natural
Heritage Data System operated by the Washington Natural Heritage Program (De-
partment of Natural Resources) and the Nongame Wildlife Program (Department of
Game). To protect these rare resources from vandalism, the exact locations are
not identified.

The listing of special plants, animals, and ecological communities should not
be considered complete, as it is based on fortuitous discoveries, not on a com-
prehensive survey of the valley.

Flood control or management works could adversely affect special species'
habitat and production by impairment or destruction of streamside vegetation.

Table 3.7. KNOWN OCCURRENCES OF SPECIAL PLANTS, ANIMALS, AND COMMUNITIES, SKO-
KOMISH VALLEY, MASON COUNTY, WASHINGTON.

------- ---- ------ -------- --- -----
Element Name Status Location and notes

-------------------------------------------------------------------------------
PLANT SPECIES
Woodwardia fimbriata Proposed State Known from two streamside locales:
Chain-fern Sensitive near the-river's mouth and on the
ANIMAL SPECIES main stem.
H. leucocephalus Federal & State Breeding at two streamside
Bald Eagle Threatene d locales: at the river's mouth and
the confluence of the forks.

Martes pennanti Proposed State Known from one location near
Fisher Sensitive Purdy Creek

COMMUNITY TYPES
None yet reported within the Skokomish Valley.
------------------------------------- 7----- ------------------------------------
Source: Natural Heritage Data System .

SOCIOECONOMIC SYSTEMS
The social and economic systems of the Skokomish Valley are a subset of the
larger systems operating throughout the Puget Sound region. Of predominate im-
portance locally is the Skokomish Indian community at the mouth of the valley,
and the agricultural community in the main portion of the valley. Notable out-
side influences are the regional economy and the programs of local, state, and
federal agencies of government.

POLITICAL SUBDIVISIONS
The Skokomish basin overlies three federal reserves, the Olympic National Park,
the Olympic National Forest, and the Skokomish Indian Reservation; three coun-
ties, Mason, Grays Harbor, and Jefferson; and a number of special districts.

Olympic National Park: The Olympic National Park (ONP) has jurisdiction over
most of the North Fork basin above the inlet to Lake Cushman. National Park
lands are managed for preservation of natural'habitats and low intensity recre-
ation. The only National Park facility and station in this portion of the park
is at Staircase Campground a few miles above the inlet to Lake Cushman.

Olympic National Forest: The Olympic National Forest (ONF) has jurisdiction
over most of the South Fork basin and a small portion of the North Fork Basin.
National Forests are managed primarily for timber production and secondarily
for other uses such as minerals, grazing, and recreation. With the exception
of Brown Creek Campground and the Skokomish River Trail from Brown Creek Camp-
ground to the ONP, the South Fork basin under ONF jurisdiction is managed for
intensive timber production. This portion of the basin and the National For-
est has an unusually high density of logging roads.

Skokomish Indian Reservation: The Skokomish Indian Reservation covers about
7.5 square miles north of the main stem near the mouth of the river. About
half the reservation lies on the flood plain, with an elevation of less than 40
feet (Molenaar & Cummans, 1973).

The Skokomish Indian Tribe has jurisdiction over tribal and individual trust
lands within the Reservation boundaries. However, substantial portions of the
reservation have been lost to tribal ownership through alienation of privately
owned land,@and condemnation for public purposes such as Tacoma City Light's
powerhouse facility. Mason County can assert land use regulatory authority
over alienated lands within the Reservation.

The Tribe has no formal, institutionalized land use planning or regulatory pro-
grams, including flood plain management or zoning.

County Government: The Skokomish basin lies within three counties: Mason,
Grays Harbor, and Jefferson. Only minor portions of the basin lie within the
latter two counties, however. Fringes of the headwaters of the South Fork ba-
sin are within Grays Harbor and Jefferson counties, and the headwater tributar-
ies of the North Fork are within Jefferson County. These headwater areas are
also wholly within the Olympic National Park and Olympic National Forest. The

area of interest within the basin regarding flooding, the Skokomish Valley of
the South Fork and the mainstem lies wholly within Mason County.

For purposes of this plan, therefore, the only local government involved is Ma-
son County. Mason County's regulatory programs which affect the Skokomish Val-
ley are principally the Shoreline Master Program (under the state Shoreline
Management Act). These regulatory programs are addressed in Chapter 6.

Drainage District: No drainage district has been established in the Skokomish
Valley.

Flood Control District: The Skokomish Flood Control District was established
in 1976 under the authority of the Flood Control Zone Districts Act (Chapter
86.15 RCW). The district boundaries were established as the Skokomish River
watershed, less those portions lying within Gray's Harbor and Jefferson coun-
ties, Olympic National Park, Olympic National Forest, and the Skokomish Indian
Reservation.

Flood Control Zone Districts may be established for the purpose of "undertak-
ing, operating, or maintaining flood control projects or storm water control
projects or groups of projects that are of special benefit to specified areas
of the county" (RCW 86.15.020). A five member Advisory Committee composed of
Skokomish Valley residents was appointed by the Mason County Commissioners in
accordance with RCW 86.15.070. As a quasi municipal corporation, Flood Control
Zone Districts have taxing authority; the Skokomish Flood Control District
taxes property within the district at $0.50 per $1,000 assessed valuation.
The District's Flood Control Plan identified three action priorities for the
District Advisory Committee:

L. Develop a maintenance program that will protect and/or restore all
existing flood control facilities;
2. Increase the water flow capacity of the main stream channels; and
3. To construct and maintain new dikes and barriers in locations which
will reduce flood hazards;

and four specific work projects:

1. Clean channel and bank at State Highway 101 bridge (including the
gravel island one-third mile up river);
2. Debris removal in selected areas, i.e. at the old Crossman place;
3. River bank stabilization, i.e. at the church; and
4. Eliminating point sources whe@e gravel is entering the river system,
i.e. the bluff below McKay Flats.

In the past, the monies raised by the District through taxation have been used
to finance minor instream gravel removal, instream earthmoving, and streamside
dike construction. Few of these projects have been of a substantial enough na-
ture to resist subsequent destruction or deterioration by flood waters.

Soil and Water Conservation District: Mason County is served by a Soil and Wa-
ter Conservation District which is inactive. Staff support is provided by the

Thurston County district with offices in Olympia.

POPULATION AND HOUSING
Mason County population grew at a rate of approximately 5% a year during the
period 1974 - 1982 (Mason Regional Planning Council, 1982). In recent years,
however, the average annual growth rate has decreased to little more than 2% as
summarized in Table 3.8. During the 1980 - 1986 period, deaths (1674) exceeded
natural increase (1320), thus most of the total increase (4216) is due to mi-
gration (2896). -

By comparison, during the 1980 - 1986 period when Mason County population in-
creased by 13.52%, Washington state population growth was 6.95%, and adjacent
counties were experiencing the following growth: Thurston, 14.43%; Kitsap,
11.79%; 12.12%; Grays Harbor, -5.00 (OFM, 1986:29).
Mason County population growth is typically attributed to "spill over" growth
from Kitsap and Thurston counties. If this were to be true, population growth
would be expected to exceed employment growth. However, during the period 1980
1986 when Mason County population growth averaged 2.14% annually, employment
growth averaged 2.19% annually despite a slump during the 1981 - 1982 recession
period. This is indicative of a population growth attributable to internal
growth, not external growth. In fact, it it likely that Mason County's popula-
tion and employment growth is influenced by growth in the Port Orchard and
Olympia areas of Kitsap and Thurston counties.

The population data, of course, includes only permanent residents. Many owners
of second homes also live in the county for much of the year and place a demand
on certain public services. This is particularly true of the communities and
developments along Hood,Canal, but is not thought to be significant in the Sko-
komish Valley. Many second homes are being converted to permanent residences
as their owners retire and move to Mason County permanently.

For the remainder of the 20th Century, Mason County.population is expected to
grow at about the same rate as in the recent past (see Table 3.8). No employ-
ment projects are known to be available.

ECONOMIC SECTORS
The economy of the Skokomish basin is based on its natural resources. The
principal economic sectors are timber and tourism. The timber industry relies
on the public and private commercial forests. In the past, intensive timber
harvest in the Shelton CSYU yielded a large number of woods and mill jobs; most
of this employment was held by persons residing outside the Skokomish basin in
Mason and Grays Harbor counties. The tourism and hospitality industry relies
on the forest preserves of the Olympic National Park and the attraction of Hood
Canal. Secondary economic sectors include shell fisheries in Hood Canal, ser-
vice businesses such as food service, retail sales (e.g. convenience stores,
gasoline, and fireworks), and government employment (e.g. fish hatcheries and
Tribal government).

The economy of the Skokomish Valley is based on agriculture, and therefore the
soil resource. Dairy farming was once the predominate business and land use in
the valley. In the 1950s dairying began to decline, and by the 1980s had

Table 3.8. MASON COUNTY POPULATION (1980 - 1986) AND FORECAST (1990 - 2000).
-------------------------------------------------------------------------------
Year Unincorp. Shelton Total Average Annual Total
Areas Growth Rate, % Employment

-------------------------------------------------------------------------------
1'980 23,555 7,629 31,184 10,180
1981 24,300 7,600 31,900 9,750
1982 24,960 7,740 32,700 9,370
1983 26,000 7,600 33,600 12.14% 10,750
1984* 27,200 7,600 34,800 10,940
1985 27,250 7,550 34,800 11,300
1986 27,850 7,550 35,400 11,590

1990 38,156
1.99%
1995 42,099
2000 46,840 2.16%
-------------------------------------------------------------------------------
Source: Office of Financial Management, 1986:5, 57 (population data); US De-
partment of Labor, Bureau of Labor Statistics (employ'ment data).

vanished from the valley. In recent years Christmas tree farming has become
popular here, as elsewhere in Mason County. Some dairy farms are operated for
cattle production. Many farm operators have abandoned dairying, but not yet
converted to another form of agriculture; their fields lie-idle.

LAND USE
Most of the basin is forested, either as forest preserves in the Olympic Na-
tional Park, or as managed timber forests in the Olympic National Forest or on
industrial timber lands. Only in the Skokomish Valley of the South Fork and
the mainstem, and to a lesser degree along the southeastern shores of Lake
Cushman, are other land uses found. - I
Most of the South Fork basin is a part of the Shelton CSYU, a cooperative for-
est management agreement between the Olympic National Forest and Simpson Timber
Company covering lands managed or owned by both parties. The Shelton CYSU,
formed in 1946 under the Sustained Yield Forest Management Act of 1944, is the
only cooperative CYSU program in the nation. The annual timber harvest from
the CYSU is summarized in Table 3.9 along with projections for the next decade
(ONF, 1986a, b). During the past decade timber harvest has been 40 to 70 mil-
lion board foot per year higher that during the first three decades of op-
eration of the CYSU. During the next decade (1987-96) timber harvest from the
CYSU is expected to decline slightly, but will remain higher than during the
first three decades of operation.

General land use in the Skokomish Valley can be characterized as rural residen-
tial and agricultural. Residences are scattered about in the valley, with a
small concentration in the area of Mohrweis near the confluence of the North
Fork and the South Fork.

Table 3.9. SHELTON CYSU AVERAGE ANNUAL TIMBER HARVEST.

------- ------ ------ -------- ------- ----- ----
Average Annual Timber Harvest, million board feet
------------------------------------------------------
Year National Forest Simpson Total
-19-4-7---5-6- ---- al-1-o-w-a-b-l-e- ---------------------------------------------------- 100.0 ----
actual 54.2 46.4 100.6

1957-66 allowable 116.0 19.0 135.0
actual 98.3 35.4 133.7

1967-76 allowable 116.0 19.0 135.0
actual 102.4 22.2 124.6

1977-86 allowable 93.8 94.4 188.2
actual 87.7 86.2 173.9

1987-96 allowable 46.1 118.7 164.8
expected 1.5 152.6 154.1
---------------------- 7 --------------------------------------------------------
Sources: ONF, 1986b:III-184; ONF, 1986a:III-9.

PUBLIC SERVICES AND UTILITIES
This section addresses public services and utilities within the primary study
area.

Sewage Disposal: There are no sewer service facilities in the Skokomish Val-
ley. Sewage treatment and disposal by means of individual septic systems and
leaching fields. The soils of the Skokomish Valley are mostly alluvium. The
water table is seasonally variable, ranging from a few feet below the surface
during the summer, to at or near the surface during the winter. These condi-
tions form severe limitations on residential development using conventional
on-site sewage disposal methods. Seasonally high water tables can inundate
septic tanks and saturate leach fields, and the leachate can contaminate aqui-
fers tapped by shallow domestic wells (Foxworthy, 1975); see also Table 3.2.

Hydropower: Tacoma City Light operates two related hydropower facilities on
the North Fork, Cushman Reservoir (Cushman I powerplant) and Lower Cushman Res-
ervoir (Cushman II powerplant); see Figure 3.1 for locations. The basic char-
acteristics of these facilities are summarized in Table 3.10. The total rated
capacity of the two power plants (124,200 kW) is 18% of the total rated capac-
ity of the entire Tacoma@City Light power system. The Cushman facilities were
licensed by the Federal Power Commission as single purpose hydropower fa-
cilities.

In the early 1980s Public Utilities District No. 3 of Mason County (PUD 3) con-
ducted feasibility studies of three alternative large hydropower developments
on the South Fork. A Draft Environmental Impact Statement (DEIS) was issued in
February 1983. The proposal is currently dormant. The project would'have

Table 3.10. CHARACTERISTICS OF CUSHMAN I AND CUSHMAN II HYDROPOWER FACILITIES,
NORTH FORK SKOKOMISH RIVER.

-------------- ------- - ------- --
Characteristic Cushman I Cushman II

-------------------------------------------------------------------------------
Construction completion 1926 1930

Total storage, acre-feet 453,350 8,000

Usable storage, a-f 372,000 2,500

Total rated plant 43,200 81,000
capacity, kilowatts

Average annual genera- 127,000,000 233,000,000
tion, kWH

------- ---- -----
Source: TCL, 1985;

included a 292-foot-high dam on the South Fork at RM 9.1, creating a
6-mile-long reservoir. The project would have modified flows in the lower
South Fork and the main stem by augmenting low flows and reducing high flows.
Floods that are an annual occurrence in the Skokomish Valley would have been
reduced in size and frequency due to the proposed reservoir's minimum 25,000
acre-foot flood storage capacity. Flood flows of up to the 10-year recurrence
interval could have been contained by this storage capacity. More severe flood
flows could have been mitigated, but not wholly contained. Large floods (e.g.
the 100-year event) could not have been contained, and the extent of the flood-
plain of the Skokomish Valley would not have been reduced (CH2M Hill, Inc.,
1983). The reservoir' would also have contained the sediments and bedload which
are presently being transported from the upper South Fork into the lower South
Fork and the main stem causing riverbed aggradation.

TRANSPORTATION
The transportation network in the primary study area is shown on Figure 3.2.
Access to points north is provided by US 101 to Port Townsend and thence by
ferry to Whidbey Island, and Port Angeles and thence by ferry to Vancouver Is-
land. Access to points east is provided by SR 106 and SR 3 to Bremerton and
thence by ferry to Seattle and highway 1 5. Access to the south is provided by
us 101 to Olympia and highway 1 5. Limited access to the west is provided by
Olympic National Forest roads.

The transportation system of the Skokomish Valley is unusual for a Pacific
Northwest river valley. Historically, trails and early roadways were built
along the borders of the valleys in practical acknowledgment that the valley
bottoms were inundated every winter (Sedell & Luchessa, 1982:211). This prac-
tice is exemplified in the lower Skokomish Valley by the alignment of Purdy
Cut-Off Road (Road 4178) and a portion of SR 106 which are constructed at the
base of the slopes on the southeast side of the valley. In contrast, Skokomish
Valley Road (Road 4164) and Bourgault Road West (Road 4196) were is constructed

largely on public land survey lines on the valley floor, crossing many side
channels of the original river system. As a result of the improper location of
these roads, they are frequently flooded; this issue is discussed in Chapter 5.

Highway US 101 was constructed on fill across the Skokomish Valley to protect
the roadway from frequent inundation during winter high flow periods. The
highway bridges the main stem and a secondary channel approximately 1,000 feet
north. Nonetheless, the highway elevation is insufficient to prevent occa-
sional flo.oding of the roadway. The highway fill also acts as a dam, lessening
the flooding of some downstream properties on the south side of the'ri'ver, and
contributing to the frequency, severity, and/or duration of flooding of some
upstream properties. This effect is discussed in Chapter 5.

Highway SR 106 was also constructed on fill across the Skokomish Valley but at
a lower elevation than US 101. The Bureau of Indian Affairs (BIA) is currently
investigating alternatives for rebuilding and raising the elevation of SR 106
for the Skokomish Indian Tribe.

There are no local public transportation routes serving the Skokomish Valley.
Mason County does not operate a public transit system.

RECREATION
Recreation in the Skokomish basin is focused on hunting and fishing, hiking and
camping, and water sports. The Olympic National Park and Olympic National For-
est maintain trail systems out of the USFS Brown Creek Campground on the South
Fork and the. road heads along Lake Cushman and the North Fork. At Lake
Cushman, the state Parks and Recreation Commission maintains a campground and
the City of Tacoma provides a boat launch facility.

The only established public recreation facility in the primary study area is a
Washington Department of Game fishing access on the left bank of the main stem
in Section 8, T21N, R4W, near RM 6.7 (Hutchison, 1976) which also provides a
rough boat launch. (Rough boat launches are defined as unimproved launch areas
which can be utilized by small trailered boats.) Additionally, there is an in-
formal fishing access to the right bank of the South Fork approximately a half
mile west of Mohrweis (RM 0.5) at which it is possible to launch car top car-
ried boats.

The two state highways, US 101 and SR 106, which cross the Skokomish Valley are
Designated State Scenic Highways (Hutchison, 1976).

The overall river recreation values of three segments of the Skokomish system
have been evaluated under the Pacific Northwest Rivers Study of the Northwest
Power Planning Council (NPPC) and Bonneville Power Administration (BPA). An
upper segment of the South Fork, from the headwaters area in Olympic National
Park, down to the Pine Creek confluence (RM 19.2) in Olympic National Forest is
rated A (high recreation value) overall, and A for its camping and picnicking,
and hiking and backpacking values, and B (above average) for its wildlife view-
ing values. A middle segment, from Pine Creek down to the Brown Creek
confluence (RM 12.8) and US Forest Service Brown Creek Campground is rated B
overall and B for its hiking and backpacking, and wildlife viewing values, and
C (average) for its camping,and picnicking values. A lower segment, from Brown
Creek down to the river's mouth on Hood Canal is-rated C overall, and B for its

flatwater boating values, and C for its whitewater kayaking values (Anderson,
et al., 1986).

The value of the river for boating (e.g. canoeing, kayaking, or rafting) is
limited by the danger of log jams and sweepers (logs protruding over the river
from the banks). Additionally, the past and continuing (illegal) practice of
riprapping the river banks with automobile bodies forms an endangerment to
boaters who might be swept by the river current into an automobile body and
drowned.

CULTURAL RESOURCES
According to the state Office of Archaeology and Historic Preservation (Whit-
lam, 1987), there are no recorded cultural resource sites within the Skokomish
Valley. However, it is clear that given the traditional occupation of the val-
ley by ancestors of the present Skokomish Indian Tribe, that cultural resource
sites would be likely to be abundant.

SUMMARY AND CONCLUSIONS
The following discussion summarizes pertinent findings on the characteristics
of the Skokomish River basin and Skokomish Valley, and presents conclusions
based on those findings that are pertinent to future development, occupation,
and flood control management measures.
At four locations, the river flows close by unstable or potentially unstable
canyon slopes. If not properly managed to limit or prohibit development or
earthmoving in these areas, these slopes could be a source of landslide mate-
rial which could block the river's flow, causing or aggravating flood
conditions.

River bed aggradation appears to be both severe and the immediate cause of in-
creased an increased rate and severity of flooding in the Skokomish Valley.
The source of the gravels causing the aggradation appears to be in the upper
South Fork basin within the Olympic National Forest. The South Fork basin is
characterized by steep unstable slopes and erosion prone soils. Both natural
landsliding and slope failures induced by forest practices may be contributing
to @edimentation of the South Fork. To a lesser degree, forest road construc-
tion and operation may also be contributing sediments.

The soils of the Skokomish Valley are characterized as wet, being subject to
inundation, and having high water tables. As a result, these soils have severe
limitations for on-site sewage disposal and building construction, and are
poorly suited for residential development.

Drainage from the Skokomish River basin (cfs/sq mi) is approximately double
that of basins on the east side of Puget Sound. This is partly a natural func-
tion of the greater annual precipitation volumes on the east slope of the Olym-
pic Mountains as compared with precipitation on the west slopes of the Cascade
Range. The role of other factors such as land use practices and soil charac-
teristics is speculative.

Water quality violations are not known to be a problem in the Skokomish River
system. Water quality monitoring data show no chronic or gross violations of.
state water quality criteria.

Land use in the Skokomish Valley is dominated by agriculture. Formerly
dairying was the predominate form of agriculture; since the 1950s dairying de-
clined until no commercial operations remained. Currently, Christmas tree
farming is the predominate form of agriculture. The state of Washington oper-
ates three fish hatcheries in the Skokomish Valley.

Chapter 4

HYDROLOGY AND FLOODING CHARACTERISTICS

INTRODUCTION
The pertinent hydrogeologic and hydrologic issues affecting flooding of the
Skokomish Valley include the diversion of the North Fork directly to Hood Ca-
nal, the filling of old side channels to the river, the plowing over of valley
floor drainages, accretion of the river bed, decreased bank full flow volumes,
and river bank erosion. Cause and effect relationships are discussed in a
speculative manner, and recommendations are made for research necessary to
quantify or confirm relationships.

CLIMATE
Generalized aspects of Skokomish basin climate are discussed in Chapter 3. Ad-
dressed here in Chapter 4 are precipitation, snow cover, and evaporation.

PRECIPITATION
Mean annual precipitation onto the Skokomish basin ranges from 200 to 220
inches per year on the Olympic crest in the upper watershed, to 80 to 90 inches
per ye.ar in the Skokomish Valley and 75 to 80 inches at the mouth of the river
(Phillips, 1986; Molenaar & Noble, 1970). Average precipitation across the ba-
sin is about 133 inches per year. Records kept at Cushman Dam indicate an av-
erage annual precipitation of 100.25 inches, with extremes of 132.09 inches and
69.24 inches. Peak daily precipitation records of'six to seven inches occur
between November and February (Phillips, 1986). Given the rugged terrain and
dissection of the basin landscape by river canyons, rainfall can be expected to
be highly erratic between sub-basins of the Skokomish basin.

More than three-fourths of the yearly precipitation, mostly rainfall but with
some snow, occurs from early October through March (Molenaar & Cummans, 1973).

SNOW COVER
During the winter, much of the precipitation in the mountainous part of the
Skokomish River occurs as snow. The snow remains as snowpack until spring and
early summer, when it melts and provides most of the water to the streams dur-
ing the dry summer months. Winter snow storage is common to most river basins
in western Washington which have headwater areas at altitudes generally above
4,000 feet above sea level (Molenaar & Cummans, 1973).

EVAPORATION
No evaporation measurements are known to have been made in or near the Skoko-
mish basin. Based on studies conducted in Seattle (45 miles northeast) and
Puyallup (45 miles east), the annual evaporation from a Class A pan is esti-
mated to be 25 to 35 inches. Annual evaporation from lakes and reservoirs is
estimated to be 20 to 25 inches. Average monthly evaporation rates range from
less than an inch from November through February, to over six inches during
July (Phillips, 1968).

HYDROLOGY
Stream flow is dependent on precipitation and its disposition as rainfall
and/or snowmelt. This section is introduced with a generalized discussion of
hydrology, followed,by a discussion of Skokomish River system hydrology.

Additionally, the hydrologic characteristics of a river are closely linked to
the geomorphologic characteristics -- that is, the geology and morphology, or
form of the landscape. Whether a river is meandered or braided as it flows
across a plain or whether it is a deeply incised canyon is a function of both
the geology of the landscape, the volumes of water carried, and the volumes of
sediment moved by the flowing water.

INTRODUCTION
Initially, a portion of the rain falling on the landscape is intercepted by
vegetation, and in some areas by impervious surfaces. Rainfall intercepted by
vegetation evaporates back to the atmosphere. Most rainfall intercepted by im-
pervious surfaces contributes to storm runoff, although small amounts will
evaporate to the atmosphere. In urban (or other built up) areas, impervious
surfaces include pavement (roads, sidewalks, and parking lots), buildings, and
effectively impervious surfaces such as compacted soil. In natural areas, ef-
fectively impervious surfaces include wetlands, shallow soils which become
saturated early in the winter rainy season, and rock outcroppings.
I
Of the remaining rainfall, a portion infiltrates the ground and a portion runs
off immediately as surface runoff. In the Skokomish basin, the permeability of
most soils exceeds most rainfall intensities, thus there is little or no im-
mediate surface runoff from most areas. Of that which infiltrates the ground,
a portion is taken up by the plants, and through the process of transpiration,
is evaporated back to the atmosphere or is embodied in the plant. The remain-
der moves slowly through the ground water into deeper aquifers, or through
near-surface aquifers to emerge later at lower elevations as delayed runoff
stream flow.

An approximate description of the disposition of rainfall on the Skokomish ba-
sin is summarized in Table 4.1 which is based on a concept for estimating rain-
fall disposition developed by Woolridge (1971). Different analysts will use
different (and equally valid) approaches to the development of water budgets
such as Table 4.1, thus the values in other studies of the Skokomish (e.g.
Harr, 1982) will vary; what is important is the relative magnitude of the val-
ues.

Water draining off the landscape and through the ground water carries with it a
load of suspended and dissolved solids; the drainage process is also a process
of land leveling or erosion. The rates of erosion can be slow and impercep-
tible as in rain splash erosion, or moderate as in sheet, rill, and gully ero-
sion, or catastrophic and; ramatic as in landsliding. Once deposited in a
stream, sediments are moved down stream continuously as a part a part of the
suspended sediment load, or periodically as a part of the bedload which is
rolled along the bottom by higher flow velocities.

River geomorphology models portray river zones as proceeding from a head waters
fixed zone through braided and meandered zones to an estuarine delta (see Table
4-2), but in nature the zones are not clearly distinguishable and are usually

Table 4.1. ESTIMATED EXISTING ANNUAL RUNOFF CHARACTERISTICS, SKOKOMISH BASIN.

-------------------------------------------------------------------------------
Event or Process Natural Conditions: Existing Conditions:
<1% effective Cushman Reservoir
impervious surface diversions
Annual-precipitation ---------- 133 ----------------------- 133 ---------------------

Interception by
vegetation (evaporated) 3 3

Interception by
impervious surfaces
(contribute to runoff) <1 <1

Infiltration into the
ground 130 130

Evapotranspiration
by vegetation 17 17

Total Runoff Available 113 113

Storm Runoff
(surface water) 1 1

Delayed Runoff
(ground water) 112 112

Cushman Diversions 0 43

Net Runoff to Main Stem 113 69

-------------------------------------------------------------------------------
1. Based on Woolridge (1971) and others; see text.
2. All values in inches per year, as in inches of rainfall.
3. Effective impervious surface includes consideration of saturated soils un-
der natural conditions.

in a mixed and repetitive order because river gradients do not uniformly de-
crease from headwaters to mouth. The fixed (boulder) zone is often synonymous
with "V" shaped canyons, steep terrain, and high erosion rates. The braided
zone is often associated with "U" shaped valleys and fixed zone tributaries.
Braided river reaches are usually dynamic, shifting systems which occur where
there has been a decrease in river energy due to decreased gradient or diverted
flow, or to an increase in sediment supply. The meander zone is usually as-
sociated with broad lowland floodplains. Meander patterns migrate downstream
as the leading edge of a meander erodes its bank while the following edge of
the meander is depositional (accretional). For this reason, modern floodplain
management practices often include a prohibition of any substantial construc-
tion in the meander belt, a corridor bounded by the outer extremes of meander-
ing. Deltaic zones are usually associated with the estuarine mouths of rivers,

Table 4.2. RIVER GRADIENT, MORPHOLOGY, AND BED MATERIAL MODEL.
-------------------------------------------------------------------------------
Channel Channel Bed Material Comments
Character Gradient Material Budget
-------------------------------------------------------------------------------
Fixed >25 ft/mi Cobbles to Eroding to Usually found as
boulders neutral a headwaters reach

Braided 5-25 ft/mi Sand to Accretional Usually found as a
gravel to neutral mid-elevatio'n
reach, but may
occur at lower
elevations

Meandered 0-5 ft/mi Silt to Usually Usually found as a
sand accretional lowlands reach

Deltaic 0 ft/mi Clay to Acc retional Typically an
silt estuarine delta
but may occur at
lake and reservoir
inlets.

------------------------------------------------------------------------------
Source: adapted from Proctor, et al., 1980:1, Figure 2-3.

but may also be found at the inlets to lakes and reservoirs where substantial
sedimentation occurs. Some geohydrologists consider the deltaic zone to be a
specialized form of the braided zone.

SKOKOHISH RIVER SYSTEM
The Skokomish River system is described and mapped in Chapter 3,(Physiography
section; Figure 3.1). In both a flood control management context and a water
resources context, it is most useful to subdivide the Skokomish basin into (1)
the North Fork basin above Tacoma City Light's Cushman facilities, (2) the
South Fork basin above RM 3.5, and (3) the Skokomish Valley comprised of the
lower North and South Forks and the main stem.

Hydrology: The Skokomish river system is unusual if not unique in its condi-
tion of having substantial portions of its flow diverted out of the basin.
Since 1930, Tacoma City Light has diverted virtually all the flow of the North
Fork directly to its powerhouse on Hood Canal from its Cushman projects. Only
the South Fork makes substantial contributions to flows in the main stem and
the flooding problems of the Skokomish Valley. This is reflected in Table 4.1
as the difference between "natural conditions" and ."existing conditions." Av-
erage annual (mean, maximum, and minimum) discharges at selected USGS Gage lo-
cations are summarized in Table 4.3 showing the relative amount of flow di-
verted by the Cushman project -- approximately 38% of the average annual flow.
The Cushman Project diversions are diagrammed in Figure 4.1. Morrison-
Maierle, Inc. (1979) estimate that the Cushman diversions have reduced flows
near the mouth of the North Fork to 13% of estimated natural values.

Table 4.3. DISCHARGE STATISTICS, SKOKOMISH RIVER SYSTEM.

-------------------------------------------------------------------------------
River Reach Location USGS Gage Average Discharge, cfs
River Mile Number ----------------------------------
Mean Maximum Minimum
North-Fork ----- Cushman -------- 12056500 -------- 502.5 ----- 755.0 ---- 256.0 ---------
29.2 Inlet

North Fork Cushman 12057500 755.9 1019.0 137.0
19.6 Outlet

North Fork Mouth 12059500 115.2 311.0 36.6
10.0

South Fork Mouth 12060500 732.0 1041.0 424.0
3.1

Main Stem us 101 12061500 1194.5 1756.0 635.0
5.3 bridge

Source: Williams, et al., 1985.

Erosion: Erosion and sedimentation rates are not known to have been measured
in the Skokomish basin. As discussed in Chapter 3, the soils of the mountain-
ous regions of the Skokomish basin are characterized as being unstable and
highly erosion prone when devegetated or disturbed. Additionally, the inten-
sive logging of the Shelton CSYU porti,on of the South Fork basin has resulted
in an increase in the rate of erosion'from intensively logged lands by a factor
of approximately 3.6 over undisturbed conditions (ONF, 1986b).

Additionally, land slides directly into the South Fork, as described in Chapter
3, are also known to have occurred.

Channel Morphology: Channel morp hology changes in the primarily study area,
the Skokomish Valley, are of particular importance for two reasons: (1) the
streambank erosion and deposition associated with channel shifts and meander
migration, and (2) the riverbed aggradation which is causing more frequent and
severe flooding. Throughout geologic time, that is, the past 10- 12,000 years
since the retreat of the glacier from the Skokomish Valley, the main stem has
meandered across the entire valley floor. In the context of geologic time, the
present location of the main stem on the north side of the valley is temporary.

During the past 120 years, gradual, cumulative shifts and migrations of the
main stem and lower North and South forks can be traced from mapping and aerial
photographs as shown in Figure 4.2. Figure 4.2 depicts river channel locations
during the 1860s and 1870s; 60 to 70 years later in the 1930s; and 50 years
later in the present. The base map of Figure 4.2 is derived from current
(1986) USGS quadrangle maps of the area which in turn are based on 1979 aerial
photography; the base map was partially updated to current (1987) conditions

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based on field observations and aerial photography. The configuration of the
river channels in the 1930s is taken from a 1935 Washington Department of Con-
servation and Development flood control plan map of the Skokomish Valley. The
level of accuracy of this map is unknown. The configuration of the river chan-
nels in the 1860s and 1870s is derived from US Government Land Office (GLO)
survey maps produced to depict the original subdivision of the area into sec-
tions and townships:
Township 21 North, Range 4 West -- 1861
Skokomish Indian Reservation -- 1871
Township 21 North, Range 5 West -- 1875
The accuracy of this mapping is known to be faulty in some locations. The
channel locations of the original mapping along the line between Townships 4
and 5 do not match. The configuration in Figure 4.2 was derived by adjusting
contradictions to topographic conditions. In general however, the pattern of
the river depicted in Figure 4.2 for the 1860s and 1870s is representative of
that time if not absolutely accurate.

During the 60 to 70 years leading up to the 1930 s, the lower South Fork mean-
ders shifted considerably with no apparent pattern. The lower North Fork
changed in pattern to more pronounced meandering. The confluence of the forks
migrated downstream approximately 1/4 mile. From the confluence (RM 9) down to
the location of the old highway bridge (RM 6), the main stem maintained its
course in a general sense, with the meanders forming more intricate patterns,
including the development of secondary channels. From the old bridge down to
RM 4, substantial channel changes took place: a second main channel formed
south of the Section 15 meanders in a newly cut channel. The lower four miles
of the river remained virtually unchanged.

During the 50 years between the 1930s and the present, the lower South Fork
continued to exhibit instability and major meander migration. The confluence
shifted north slightly. From the confluence (RM 9) down to the location of the
old highway bridge (RM 6), the main stem meanders migrated slightly, and the
secondary channels were abandoned by the river or filled by landowners. From
the old bridge down to RM 4, abandonment and filling of the Section 15 meanders
shifted all main stem flow to the current channel. The lower four miles of the
river remained virtually unchanged.

During the past 7 or 8 years there have been no major channel shifts, although
bank erosion continues to cause cumulative changes. Within the gravel bed
channel of the river, however, the thread of the stream has shifted substan-
tially, and a braided stream pattern is emerging on the main stem from RM 5.5
up to the confluence (RM 9) and on up the lower two miles of the South Fork.
In addition, the riverbed has been aggrading.

Bank erosion is particularly severe and threatening at two locations. In the
vicinity of the Skokomish Community Church (RM 8.1 - 8.3) the gravel bed of the
river is widening and the right bank has eroding to within 50 to 70 feet of
Skokomish Valley Road. Similarly, at RM 1.8 on the South Fork the gravel bed
is widening and the right-bank has eroded to within less than 50 feet of Skoko-
mish Valley Road.

Local residents report that the main stem river bed is "filling" with gravel or
"rising." Typical of Puget Sound lowland rivers, the main stem meanders of the
Skokomish River are dynamic and shifting. Gravel bars form, migrate, and re-

form annually. River bed filling, or more properly, aggrading, is caused by
the deposition of sediment. Aggradation (also termed accretion in more general
terms) is a dynamic process subject to seasonal and long term changes in rate,
including reversals, or erosion.

Aggradation of the main stem is occurring as confirmed by an examination of the
US Geological Survey (USGS) records for Gage 12061500 located at the US 101
bridge. During the 21 year period 1964 through 1985, the elevation of the
thread of the stream at Gage 12061500 rose 3.2 feet; during the 20 year period
1964 through 1984 the stage (surface elevation) of a 200 cfs flow past Gage
12061500 rose 3.0 feet. These changes are computed from USGS Discharge Mea-
surement Notes and Rating Curves respectively. The Gage 12061500 records do
not, of course, confirm the same rate of aggradation through out the main stem,
but do support the reports of widespread aggradation.

Aggradation of the main stem is also confirmed by the observations by the au-
thors of this report of current conditions as compared with historical aerial
photographs and maps. During the past few decades the overall pattern of the
main stem between RM 9 and RM 7, and the South Fork between RM 0 and RM 3, has
been shifting from a meandered pattern to a braided pattern, a condition in-
dicative of an increase in bed load or a decrease in stream flow or both.
Stream flow is not known to have decreased in the South Fork; virtually the en-
tire flow of the North Fork was diverted directly to Hood Canal in 1930 with
the completion of Tacoma City Light's Cushman projects.

The source of the gravel contributing to aggradation of the lower South Fork
and main stem is from the South Fork basin upstream of the Skokomish Valley,
not from within the Valley. In particular, the recent, active landslides into
the South Fork noted in the Geologic Hazards section (Chapter 3) are thought to
be a principal source along with general landscape erosion from intensively
logged portions of the Shelton CYSU (see also Appendix A). There are no known ,
active, major gravel sources in the Skokomish Valley, either along the lower
South Fork or the main stem.

River bed aggradation is progressively aggravating flooding of the Skokomish
Valley. As the river bed fills with gravel the channel capacity is reduced re-
sulting in more frequent overbank flood flows and eroding riverbanks.

FLOODING
The Skokomish River floods several times a year, principally during the period
November through March. The highest recorded peak flow occurred on 3 November
1955 with a peak flow of 27,000 cfs, probably as measured at the US 101 bridge.
The estimated return period for a flow of this volume is 30 years (FEMA,
1983:10). The much discussed "100 year flood" (Table 4.4) has not occurred in
the Skokomish Valley during recorded history.

The North Fork is estimated to contribute approximately 10% of the flood flows
in the Skokomish Valley. For example, during the December 26th flood of 1980,
main stem flows of 21,500 cfs had their source principally from the South Fork
(14,800 cfs) with the North Fork flows relatively minor (2,220 cfs) (CH2M Hill
Inc., 1983). (The balance of the main stem flow at the US 101 bridge was con-
tributed by Vance, Hunter, and Swift creeks which enter the main stem below the
South Fork.)

Table 4.4. PREDICTED PEAK DISCHARGES, SKOKOMISH RIVER SYSTEM.

-------------------------------------------------------------------------------
USGS Gage Peak Discharge (cfs) Based on Log-Pearson III Analysis
Number, (Exceedence Probability/Recurrence Interval, years)
Location 0.99/1 0.50/2 0.20/5 0.10/10 0.04/25 0.01/100

12056500 2,168 4,041 9,666 12,522 16,745 24,430
-------------------------------------------------------------------------------

Cushman Inlet

12057500 1,638 8,056 11,162 12,668 14,083 15,483
Cushman Outlet

12059500 486 2,185 3,671 4,791 6,340 8,893
No. Fork Mouth

12060500 4,376 11,685 15,767 18,235 21,118 25,.002
So. Fork Mouth

12061500 6,619 15,579 20,027 22,574 25,430 29,094
US 101 Bridge
------------------------------------------------------------------------------
Source: Williams, et al., 1985.

Peak flows (discharges) at selected gaging stations in the basin as estimated
by the US Geological Survey (Williams, et al., 1985) are summarized in Table
4.4 for 1-, 2-, 5-, 10-, 25-, and 100-year recurrence intervals. Peak flow
predictions are based on statistical models which vary slightly, thus other re-
ports on the Skokomish system provide different, usually higher estimates of
peak flows (e.g. Cummans, 1973; Flood Control Technical Committee, 1970; FEMA,
1987). This model predicts a flow at the US 101 bridge which is less than the
combined outputs of the North and South forks. This is not an error; the dif-
ference is contained in floodwater storage and flow on the Skokomish Valley.

PRE-SETTLEMENT CHARACTERISTICS
Prior to settlement by Caucasians, the Skokomish Valley was drained by numerous
sloughs and ancient meanders of the main stem of the Skokomish River. Based on
a review of the US Government Land Office land survey field notes for the sub-
division of the area into Townships and Sections in 1861, the Skokomish Valley
was densely covered by willows, Douglas Spiraea, Vine Maple, Salmonberry, and
other shrubs associated with wet or periodically flooded soils. The forest
trees were a mix of primarily willow, Red Alder, Black Cottonwood, and Western
Redcedar, also indicative of wet or seasonally flooded conditions. Lesser num-
bers of Western Hemlock and Douglas-fir were found on higher ground. The sur-
vey work was conducted during September 1861, thus the surveyor noted few por-
tions of the valley as inundated or swampy at the time.

Historically, the lowland reaches of the larger Pacific Northwest rivers were
characterized by multiple channels, numerous sloughs and old side channels, and
an abundance of snags and log jams in the channels. Stream flow through the
multiple channels was sluggish, and during the winter rainfall and spring

snowmelt seasons, the river's flow regularly over topped the channel banks and
spread across the entire floodplain for days or weeks at a time, if not the
season. Soon after settlement by Caucasians, a program of river snagging was
begun by agriculturalists, and later institutionalized by the US Army Corps of
Engineers, to hasten the drainage of peak flows and drain the floodplain land
for agriculture (Sedell & Froggatt, 1984; Sedell & Luchessa, 1982).

There is ample evidence that the Skokomish main stem was typical of Pacific
Northwest lowland rivers. In 1861, the surveyor subdividing Township 21 North,
Range 4 West, surveying north between sections 15 and 16, arriving at the right
bank of the Skokomish River, recorded in his notes: ". . . at this point there
is a large raft of timber in the river from one bank of [the] river to the
other, upon which I chain [measure] across." There were probably other log
jams in the river at that time, and even today the Skokomish main stem contains
log jams periodically, though not ones a person can walk across.

Additionally, the Skokomish Valley also exhibited the typical characteristics
of intricate drainage by.numerous sloughs (but not multiple channels); the US
Government Lands Office 1861 survey maps of Township 21 North Range 4 West and
5 West show a flood plain drained by up to six old channels and sloughs across
the valley bottom. Although many of these drainages have been filled or plowed
over by agricultural activities through the decades, even today the Skokomish
Valley shows many drainages and swales which are the remnants -of ancient
sloughs and meanders of the main stem of the Skokomish River (FEMA, 1987).

CURRENT FLOODING CHARACTERISTICS
Cummans (1973) described flood distribution and characteristics of the Skoko-
mish Valley as follows:

Three principal streams -- the North and South Forks Skokomish River
and Vance Creek -- join to form the main stem Skokomish River which
flows for 9 miles (14.5 km) in the lower valley. Vance Creek, with a
drainage area of 24.8 sq mi (square miles) or 64.2 sq km (square ki-
lometers) and the'South Fork Skokomish, with a drainage of 104 sq mi
(269 sq km) are unregulated. The North Fork (118 sq mi or 257 sq km)
is regulated, and at Cushman Dam No. 2 [Lower Cushman Reservoir]
(drainage area 99.2 sq mi or 257 sq km) the entire flow normally is
diverted to a power plant on Hood Canal. Infrequent spills and re-
leases down the North Fork and natural runoff from about 19 sq mi
(49.2 sq km) below the dam constitute the source of stream flow from
this tributary. Potential floodflows from the area upstream from the
dam are significantly reduced or excluded by the regulation and di-
version.

Overbank flooding was observed during this study [1970 - 1972] in the
main stem Skokomish River. Flooding appears to occur first at points
downstream from US Highway 101. At a river.discharge of 4,650 cfs
(cubic feet per second) or 132 cms (cubic meters per second) at pro-
file station 9 [US 101 bridge], shallow overbank flow was observed to
be spreading in the NEI/4 Section 15, the northerly 3/4 of Section
14, the SI/2 Section 11, the NWI/4 Section 12, and the SW1/4 Section
1, T21N, R4W. Discharges in the lower reach of the river exceed
4,650 cfs (1.32 cms) several times each winter and therefore parts of

the valley flood plain downstream from US Highway 101 are submerged
frequently. From records of flow obtained since 1943 at the US High-
way 101 gage, some degree of flooding is estimated to occur in this
reach on a yearly average of 1 day in November, 3 days in December, 3
days in January, 2 days in February, and 1 day in March. During the
flood of January 20, 1972 (discharge of 18,500 cfs (524 cms) and
stage of 26.3 ft (feet) or 8.02 m (meters), water was observed at a
depth of 8 ft (2.44 m) in some low spots in the E1/2 of Section 14.

Upstream from US Highway 101 the channel presently appears to contain
flows of approximately 8,900 cfs (252 cms) at a 24.4 ft (7.44 m) el-
evation at profile station 9 [US 101 bridge]. At flows greater than
this, overbank flooding occurs in the E1/2 Section 18, T21N, R4W,
wittr water overflowing south across the county road. The south
riverbank also is topped in Sections 17 and 8, and, at higher flows,
in Sections 9 and 16. Specific information was not obtained regard-
ing flooding along the entire county road i-n N1/2 Section 16 and N
line Section 17. Flows greater than 8,900 cfs (253 cms) have oc-
curred at least once each year since 1943, and as many as six times
during one year. In only two water years since 1943 (1946 and 1962)
was overbank flooding upstream from US Highway 101 considered insig-
nificant at the times of peak annual flows.

Cummans' description is still essentially valid, however, overbank flows in the
vicinity of the US 101 bridge are known to occur at lower flows in recent
years. Cummans observed that overbank flows began to occur at about 8,900 cfs
.during his 1970 - 71.study period. Current US Geological Survey rating curves
for the gage at the US 101 bridge indicate that overbank flow now occurs at
8,500 cfs. That flooding occurs at lower flows at the US 101 bridge than in
the past is confounded by the fact that flooding now appears to occur upstream
of the US 101 bridge before it occurs at the bridge. Additionally, Cummans'
1973 observation that overbank flows immediately upstream of the US 101 bridge
begin occurring at flows of about 8,900 cfs appea@ to be in contradiction with
US Geological Survey rating curves for Gage 12061500 at the US 101 bridge for
the same period which indicated overbank flow occurring at about 10,500 cfs.

An overbank flow of 8,500 cfs has a recurrence interval of about 1.2 years
based on the recurrence intervals and associated peak discharges listed in
Table 4.4; this translates into an 80% probability of an overbank flow each
year. In fact, overbank flows often occur more than once a year.

Annual flooding of the Valley between the forks and the US 101 bridge currently
exhibits the following characteristics (see Figure 4.3) based on the following
information provided by Wes Johnson, a Valley resident and member of the Skoko-
mish Flood Zone District Advisory Committee.

The Mohrweis area (see Figure 4.3) is protected from low level annual
flooding by a dike along the right bank of Swift Creek which extends from
Skokomish Valley Road downstream to the main stem, and then runs along the
right bank of the main stem to about the Section 18 - 17 line J21N, R4W).
This dike appears to be well constructed, properly compacted, and is cov-
ered by moderately dense vegetation which protects the dike against ero-
sion. At the end of this dike, approximately RM 8.4, flood waters flow
south onto the flood plain and west behind the dike, then move south

across the Skokomish Valley Road to Hunter Creek on the south side of the
Valley.

A short, low, marginally effective dike has been erected along the north
side of Skokomish Valley Road at the Skokomish Community Church. The dike
appears to be mostly loose fill with no adequate vegetation to resist ero-
sion. Overbank flow occurs at each end of this dike (RM 8.3 and 8.1), and
the flood waters flow southeast across the Valley into an old, plowed over
creek channel, and then east into Hunter Creek. Christmas tree planta-
tions in this area are clean cropped, that is, no ground cover is main-
tained, and sheet and gully erosion readily occurs during flooding.

Flood waters are also known to escape the river at about RM 7.5 in Section
8, T21N, R4W, and flow south and southeast past the fire hall and grange
hall, across Skokomish Valley Road, where there is a merger of all the
flood flows across the Valley.

East of the Section 17 - 16 line J21N, R4W) flood water flows across the
Valley becomes complex. Over bank flows in Hunter Creek continue east to-
wards the main stem. From the NE1/4, NE1/4, Section 17, flood waters flow
east across Skokomish Valley Road south of the section corner to sections
8, 9, 16, and 17; some of this flow may run northerly and return to the
main stem at about RM 6.7; some the flow probably runs southerly and
merges with Hunter Creek overbank flow.

In Section 16, flood waters flow east over the fields north of Skokomish
Valley Road, and south over the road at specific locations, and then into
Weaver Creek.

Flood water movements in Section 15 are thought to follow the pattern
mapped, but there is uncertainty about the return of flood waters to the
river. North of Skokomish Valley Road,..flood water flows east and north-
east over the old highway, and is though to reenter the main stem at about
RM 5.7. This, however, is unconfirmed, and drainage swales evident on
aerial photographs suggest that east of the Section 16 - 15 line, flood
waters may move southeast towards Weaver Creek. Flood waters which flow
southeasterly over the east - west segment of Skokomish Valley Road con-
tinue southeast across the north - south segment of the road, apparently
merging with Weaver Creek over bank flows north of Bourgault Road. It is
thought that some of the Weaver Creek overbank flow verges northeast and
reenters the main stem at about RM 5.5, but this too is unconfirmed.

Below US 101, information sources other than Mr. Johnson indicate that flood
waters enter the old slough and meander system north of the main stem in Sec-
tion 15, T21N, R4W, and flow under US 101 0.2 mile north of the main stem.
When US Geological Survey staff read the gage at the US 101 bridge coincident
with overbank flow, measurements of water depth and velocity are taken in the
main stem and the overflow channels north and south (Weaver Creek) of the main
stem. In recent years, however, the inlet to and outlet from the old slough
and meander system north of the main stem has been filled, impeding the move-
ment of flood waters. The filling of the meander system outlet at about RM 4.1
has apparently resulted chronic high ground water conditions in NE1/4, Section
14 as reported by Skokomish Tribal members, and, of course, the flood waters
which enter the slough and meander system are unable to readily escape.

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Skokomish Valley low level flooding patterns
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Highway 101 and Skokomish Valley Road (former US 101) are built on fill where
they cross the Valley in Section 15, and these road fills act as low dams,
backing up flood waters. At times of severe flooding, both roads are inun-
dated. Skokomish Valley Road fill causes the impoundment of low level flood
waters in S1/2, SE1/4, Section 16, T21N, R4W. US 101 fill causes the impound-
ment of low level flood waters in NWI/4, SW1/4, Section 15, T21N, R4W.

Flooding on the Skokomish Indian Reservation is described by Molenaar and
Cummans (1973) as follows:

Flooding or reservation lands by the Skokomish River is common and usually
occurs during periods of heavy rainfall in winter. Floodflows are charac-
terized by rapid increases in flows within a few hours, followed by de-
creases to small flows with 2 or 3 days. Several floodflows occur each
year, often in close succession. Such flows have been recorded on the
North Fork since 1913, on the South Fork since 1932, and on the Skokomish
River main stem since 1943. However, Cushman Dam No. 1 has partially
regulated floodflows on the North Fork since 1926, and since then the
large streamflows in the lower valley are almost entirely from the South
Fork basin.

At streamflows of about 2.1 million gpm [4,680 cfs] past the gaging sta-
tion [US 101 bridge], the water begins to overflow the channel and flood
adjacent lowland. Discharges of at least fhis much occur several times a
year, generally during December through March.

At least some parts of the reservation are covered by floodwaters ap-
proximately 10 days each winter, averaging 1 day each in November and
March, 2 days in February, and 3 days in December and January. The long-
est periods of flooding were 13 days in December 1966 and 18 days in
January 1'953. Flooding has occurred as early as October and as late as
May.

Flooding on the Skokomish Indian Reservation is more frequent and more severe
than on the Skokomish Valley above the US 101 bridge.

SUMMARY AND CONCLUSIONS
The Skokomish Valley floods frequently because the Skokomish basin receives an
unusually high level of precipitation. While it may seem simplistic to make
this kind of statement, it is important to remember that high rain fall inten-
sities concentrated during the winter months is the basic cause of the flood-
ing.

We conclude that the local residents' contention that the Skokomish Valley
floods more frequently and more severely in recent years, as compared with past
decades, is accurate. Our reconnaissance review of USGS Gage 12061500 (US 101
bridge) data confirm that overbank flows occur at lower discharges, and there-
fore will tend to occur more frequently.
The reason for the increased frequency and severity of flooding could be due to
(1) an increase in the volume and frequency of peak flows, (2) a reduced carry-
ing capacity of the riverbed, or (3) a combination of (1) and (2). Local
residents, at different times, have attributed recent flooding problems to both

possible causes. The Skokomish Indian Tribe initiated litigation against the
Olympic National Forest contending that forest practices had increased peak
flows in the Skokomish main stem. The case was never brought to court. Other
Skokomish Valley residents report that the river has been filling and shifting
its channel in recent years.

Harr (1982), a US Forest Service research hydrologist, investigated the rela-
tionship between forest practices and Skokomish River peak flows in preparation
for the lawsuit brought by the Skokomish Indian Tribe. Harr found no evidence
that forest management practices, including roadbuilding, in the South Fork ba-
sin have increased the size of peak flows in the South Fork. These findings
are consistent with actual research in other watersheds (e.g. Harris, 1973).

We conclude that the principal, if not the sole cause of increased flooding, is
an aggrading riverbed in the main stem and lower South Fork (see also Appendix
A). Our reconnaissance review of USGS Gage 12061500 (US 101 bridge) data con-
firm that aggradation is occurring, and at a rate of approximately three feet
during the past 20 years at that location. Additionally, the widening of the
gravel bed of the river in general, and the bank erosion at RM 1.8 on the South
Fork and RM 8.1 - 8.3 on the main stem are also indicative of an aggrading riv-
erbed.

We conclude from field reconnaissance that there is no sediment source in the
Skokomish Valley sufficient to account for the degree of aggradation which has
occurred, nor is the North Fork a sediment contributor due to the reduced flows
in that tributary. Therefore, the source of the aggrading sediments must lie
in the South Fork basin above the Skokomish Valley -- that is, from within the
Olympic National Forest (see also Appendix A).

Olympic National Forest erosion modeling (ONF, 1986b) indicates an increase in
the rate of erosion from the Skokomish basin due to forest practices by a fAc-
tor of 3.6 above natural rates. A US Army Corps of Engineers evaluation of
erosion and sedimentation in an adjacent basin of the Olympic National Forest
(Kehoe, 1982) arrived at similar co;nclusions. This suggests that a major por-
tion of the aggrading sediments could have their source on logged lands and
roads of the Olympic National Forest.
The South Fork basin is characterized by steep, potentiAlly unstable sl6pes
(Chapter 3). We have observed recent landslides directly into the South Fork
during aerial reconnaissance flights. This suggests that a major portion of
the aggrading sediments could also have their source in landsliding and other
forms of slope failure. The extent to*which these slope failures are natural
events or are induced by clearcut logging and/or forest road construction is
not known, and must be researched before a conclusive answer is possible.

We also conclude that diversion of the North Fork to Hood Canal has had mixed
effects. The diversion of all but 10 to 13% of the North Fork flow directly to
Hood Canal had a beneficial effect on flooding by decreasing main stem peak
flows. Conversely, the diminished flows in the main stem aggravate aggradation
by removing a streamflow energy source necessary to move sediments through the
main stem to Hood Canal. Further research is necessary to quantify this con-
clusion.

We conclude that a secondary effect of riverbed aggradation will be continued

severe bank erosion. River channels evolve to carry a 1.5- to 2-year flow. In
an aggrading situation the river will maintain its carrying capacity by in
creasing its width as compensation for reduced depth.

We also conclude that the partial filling of the old meander system in the
north half of Section 15 (T21N, R4W) impedes the drainage of Skokomish Valley
flood waters, and contributes to or causes chronic high ground water conditions
in a portion of the Skokomish Indian Reservation.

Finally, we conclude that the potential for a substantial shift in alignment of
the main stem should be considered. The north side of the Skokomish Valley,
where the main stem presently flows, is higher than the south side of the val-
ley as illustrated by the flood water drainage patterns in Figure 4.3. The
largest flood during historical times was a 30-year event in 1955, presumably
prior to the accelerated aggradation presently occurring. In the event of a
100-year flow -- and there is a 1% chance of that every year -- it is possible,
if not likely, that a major shift of the main stem to the south side of the
valley would occur. Most likely this would begin as head cutting on the bed or
banks of Hunter or Weaver Creek or as gully erosion and subsequent headcutting
in a clean cropped Christmas tree plantation. Head cutting is a process of
progressive, severe gully erosion, with the head of the gully eroding, or cut-
ting, upstream; when a head cut erodes through a river bank, a new channel is
formed. The consequences of a major channel shift, are, of course, not pre-
dictable

Short term measures to provide immediate protection from flooding, to mitigate
the effects of flooding, or to provide streambank protection are available and
are discussed in Chapters 7 and 8.

However, no immediate measures undertaken can be effective in the long term un-
less the broader problem of aggradation is addressed soon (see also Appendix
A). While it is clear that the key problem is aggradation, and the that the
source of the sediments lies in the South Fork basin within the Shelton CYSU, a
full understanding of the magnitude of the problem will require some quantifi-
cation of the sediment load moving into the Skokomish Valley from the South
Fork basin.

Chapter 5

HISTORIC FLOOD DAMAGES AND PLANNING

INTRODUCTION
Development in the Skokomish Valley since Caucasian settlement has always in-
cluded efforts to contain and open the channels of the Skokomish River and its
tributaries. Residents have individually and collectively worked to keep the
river clear of debris and to stabilize the stream banks where there has been
erosion. Sediment has been periodically removed from river bars. Overflow
channels have been filled and side channels have been blocked off. Small
drainages on the valley floor have been plowed over. With limited resources
and community initiative, a consistent effort has been made by residents to
manage the adverse affects of the Skokomish River on agricultural land.

Information on floodproofing of residential and nonresidential structures has
not been effectively recorded to date. In many cases, Mason County building
permit and assessor records do not reflect floodproofing or flood damage repair
work. Some residential structures have been raised to reduce flood damages.
Until the recent completion of the Mason County detailed flood insurance study
by the Federal Emergency Management Agency (FEMA), no adequate information was
available to establish a base elevation for floodproofing. Nonresidential
structures, primarily agricultural structures, have experienced repeated flood-
ing and were typically not been constructed with floodproofing measures such as
orientation of flood flows in mind.

Early flood control activities were described in the Puget Sound and Adjacent
Waters (PSAW) StUdy (Flood Control Technical Committee, 1970) as follows:

Bank Protection and Stabilization. Improvements by local interests, aided
by the Public Works Administration and the Works Progress Administration,
have been directed largely toward the prevention of bank erosion. Bank
protective works constructed prior to 1936 along the right bank of the
Skokomish River at various points consisted of training levees and and
revetments. In 1936 and 1937, the Works Progress Administration placed
four log-floated shear cables, totaling 7,900 feet in length, across the
bends where most of the erosion was taking place, and cleared the old
channel bed along the northern bank opposite the cables. The purpose of
the cables was to catch debris and divert the stream into the cleared
channel. In 1940, local interests extended and strengthened one shear
cable and improved the lower portion of Vance Creek channel. The shear
cables have provided some small local benefits, but have not accomplished
their primary purpose.

Levees. A landowner has diked a large portion of the island between the
two channels at the mouth of the river and some land west of Nalley's
Slough. This land was formerly subject to frequent inundation by high
tides and high riverflows.

Upstream Storage. Tacoma City Light has constructed two dams on the North
Fork of the Skokomish River and operates two hydroelectric plants that
have a combined maximum head of 735 feet. Cushman Dam No. 1 is ap-
proximately 9 miles above the mouth of the North Fork. The reservoir,

Lake Cushman, is 9.6 miles long, covers 4,200 acres, and has a usable
storage capacity of 360,00 acre-feet. Cushman Dam No. 2 is a reregulating
project approximately 6 miles above the mouth of the North Fork with a
reservoir 2 miles ling. The reservoir has a storage capacity of 8,000
acre-feet. A tunnel 17 feet in diameter and 2.5 miles long leads to the
powerhouse on Hood Canal near Potlatch. The Federal Power Commission li-
cense for these reservoirs does not provide for formal flood control stor-
age; however, Tacoma City Light has held the level of Lake Cushman about
10 feet below the spillway elevation during the flood season to provide
some flood storage. This voluntary action has reduced the magnitude of
floodflows in the Skokomish Valley.

In 1931, Tacoma City Light obtained a preliminary permit from the Federal
Power Commission for a proposed power project on the South Fork. Applica
tion for a license was filed on 7 September 1954. The city proposed to
increase the power output of Cushman Projects 1 and 2 by diverting water
from the South Fork reservoir through a tunnel to Lake Cushman. This pro-
posed project would have a total storage capacity of 225,000 acre-feet.
Application was filed on 8 July 1963 by the city of Tacoma to withdraw its
application for Ticense. Permission was granted by the Federal Power Com-
mission on 27 August 1963.

HISTORIC FLOOD CONTROL MEASURES
Information on historic instream and bank measures based on discussions with
Skokomish Valley residents and available records on state flood control cost
sharing projects, Hydraulic Project Approval (HPA) permits dating back to 1980,
and state Flood Control Zone Permits is summarized in this section. Unfortu-
nately, Soil Conservation Service (SCS) and Mason County Soil and Water Conser-
vation District records, the most detailed information on historic activities,
have been destroyed without any summaries kept of the information.

STATE FLOOD CONTROL PARTICIPATION:
From 1949 through 1973, Mason County and the State of Washington participated
in the cost of ten flood control work projects throughout the Skokomish Valley,
with the state contributing close to 50% of the expenses. The majority of the
projects were sediment removal from river bars and debris removal for the pur-
pose of maintaining the channel capacity and reducing bank erosion. Records do
not indicate the exact location or volumes of material removed from the Skoko-
mish River or Vance Creek. Flood control cost share work is summarized in
Table BI, Appendix B.

The first major rock revetment project was constructed on Vance Creek in 1950
and included sediment removal and the placement of a groin. An extensive dike
which extends along the left bank of Vance Creek for almost a mile and which
has alleviated the regular historic flooding, appears to have been constructed
in 1953. Another major project during 1953 included changing the alignment of
the Skokomish River and diking portions of the valley adjacent to the main stem
of the Skokomish River. It is not known why the dike was not continuous when
constructed, but the remaining undiked sections were never connected. Either
the Vance Creek dike or preexisting portions of the Skokomish River dike were
also repaired in 1953.

Sediment removal on bars of the Skokomish River and Vance Creek occurred in
1954, possibly in the vicinity of the previous year's diking projects.
According to valley residents, efforts were usually concentrated on the river
bank opposite the eroding bank. Work done to stabilize the actual eroding bank
may not have been conducted or included as a part of the cost share projects.

The last cost share project through the state's flood control participation
program was a rock revetment placed on the Skokomish River in June of 1973.
This project may have been maintenance on the previously constructed dikes
along the main stem of the river.

STATE FLOOD CONTROL ZONE PERMITS:
Records dating from 1956 show a significant number of private projects were
initiated on not only the Skokomish River and Vance Creek, but also on smaller
tributaries such as Swift Creek, Purdy Creek, Hunter Creek, Weaver Creek, and
unnamed tributaries or historic side channels on the northerly side of the Sko-
komish River. Information is not available on project costs to determine the
scale of activity. Flood control zone permits are summarized in Table B3, Ap-
pendix B.

The majority of the projects involved bank revetment or riprap placement. Road
and bridge maintenance and dike construction increased, while sediment removal
from river bars and debris removal continued. It is assumed that the Soil Con-
servation Service or the local conservation district provided technical assis-
tance to most of these streambank protection projects on an advisory basis.
Design and construction standards were not established as part of the state
flood control zone permit program, therefore there were no consistent require-
ments to be enforced by the state. Project planning and design was therefore
primarily the result of private initiative and any technical assistance pro-
vided by SCS and/or the conservation district.

HYDRAULIC PROJECT APPROVAL RECORDS:
Flood control related projects approved by the state departments of Fisheries
and Games through their Hydraulic Project Approval (HPA) permit program are
,summarized.in Table B4, Appendix B.

Bank Revetment and Riprap Projects: The South Fork of the Skokomish River has
been the area of concentration for most bank revetment and riprap projects.
Almost half of all recent Hydraulic Project Approvals (HPAs) issued for private
bank stabilization on the Skokomish River have been for the area just upstream
of the confluence with the North Fork. Cabled tree or log revetments were of-
ten used in preference to boulder riprap which is not locally available.

The main stem of the Skokomish River and various Skokomish Valley creeks have
received a well distributed attention in the area downstream from the North
Fork confluence to west side of State Route 101, with most of the projects be-
ing constructed by the Mason County (3), the Skokomish Valley Flood Control
Zone District (1), the state Department of Transportation (1), and the state
Game Department (1). Those bank stabilization projects constructed by Mason
County and the Skokomish Valley Flood Control Zone District were placed on pri-
vate land with the owners permission. Three projects were privately con-

structed within a two mile reach east or downstream of the Skokomish Community
Church.

Roads and Bridges: A bridge was constructed over Hunter Creek in 1956 by Mason
County. It is not known what had been in place previously, but it can be as-
sumed that the bridge was constructed in a way to better avoid potential flood
damage and sheet flooding which would limit access during high flows. There
are no historic records of work done on county roads within the Skokomish Val-
ley to assess historic flood damages or flood-related maintenance. No road
plan or construction effort has been made to elevate the roadway above the el-
evation of annual flooding. As noted in Chapter 3, the construction of Skoko-
mish Valley Road and Bourgault Road West on public land survey lines on the
valley floor, crossing the many side channels of the original river system, ex-
poses these primary transportation and evacuation routes to flooding on an an-
nual basis.

Vance Creek was reportedly diverted by a major 1-andslide during the early
1950s, necessitating construction of a new bridge at the present location. The
Swift Creek bridge is known locally as the old Vance Creek bridge.

Other road work consisted of revetment placed along Purdy Creek Road in 1962 by
Mason County. The US 101 bridge and culvert over Hunter Creek was replaced by
the then Washington Department of Highways in 1969. State Route 106 required
riprap revetment along main stem RM 1 in 1975, due to channel change and ero-
sion. In 1983, the state Department of Transportation replaced a bridge over
an unnamed side channel on the northerly side of the Skokomish main stem. Lo-
cal residents and historic records indicate that the side channel was previ-
ously the main stem channel. The capacity of this channel has been reduced
over time by filling for residential purposes. Also in 1983, Mason County re-
ceived a Hydraulic Project Approval to replace a culvert with a bridge over
Weaver Creek. During the same year, a private bridge was constructed over
Weaver Creek. The Vance Creek Bridge, located in the upper valley, was re-
paired and, in 1986-1987 due to channel erosion, was replaced with a sig-
nificantly floodproofed new bridge. During 1986, the state Department of
Transportation repaired the bridge over Purdy Creek and began replacement of
the State Route 106 bridge. Although the SR 106 bridge was not damaged by
flooding, it will be elevated to accommodate flooding.

Substantial maintenance has been carried out over the years on all roads, and
particularly water crossings, within the Skokomish River floodplain.. As flood-
ing continues to increase in rate and severity due river bed aggradation, the
need for road and bridge maintenance and replacement will become more regular
and extensive.

Sediment and Debris Removal: Debris and gravel removal projects have been car-
ried out by private individuals and by the Washington Department of Fisheries
in Vance Creek, Weaver Creek, Hunter Creek, Purdy Creek, and the South Fork and
main stem of the Skokomish River.

DAMAGE COST ESTIMATES
Information on damage cost estimates is scant, and based on numerous informa-
tion sources. What is known of flood damage costs from the best available
sources is summarized in Table 5.1

Table 5.1. ESTIMATED FLOOD DAMAGES, SKOKOMISH VALLEY.

-------------------------------------------------------------------------------
Event Year Dollars Notes

----- ---- ------- -----
Cushman Dam 1926 13,400 A flood control evaluation report on
constructed 1927 13,400 the Skokomish Valley issued by the US
1926 1928 13,400 Army Corps of Engineers (Dunn, 1942)
1929 13,400 estimated average annual flood damages
1930 13,400 of $13,400 from 1926 through 1941,
1931 13,400 except as noted.
1932 13,400
major flood 1933 56,600
1934 13,400
1935 13,400
1936 13,400
1937 13,400
1938 13,400
1939 13,400
1940 13,400
1941 13,400
3 Nov flood 1955 125,000(5)
30 Apr flood 1959 71,000(5)
20 Nov flood 1959 56,000(5)
15 Jan flood. 1961 114,000(5)
1962' 1,218
major flood 1964 31,486
20 January flood 1972 no data
5 March flood 1972 no data
1974 20,652(2)
69,350(4)
1975 6,924(2)
1986 110,000(2)

Sources:
1. Dunn, 1942.
2. Washington State Department of Emergency Services; flood damage reports
filed by Mason County with the State of Washington.
3. Mason County Department of Emergency Services flood damage records.
4. Soil Conservation Service,Olympia; flood damage records.
5. Flood Control Technical Committee, 1970.

CHRONIC PROBLEMS AND PROBLEM AREAS
The following identification of chronic problem areas is based on the reports
of Skokomish Valley residents. Naturally, the list will be incomplete, as we
were unable to interview all shoreline property owners in the Valley.

Agricultural soil erosion is a problem for operators of Christmas tree planta-
tions who have chosen to use clean cropping methods, that is, to not maintain a
ground cover of grass. Plantations with a ground cover show no signs of soil
loss. Clean cropped plantations show signs of both sheet and gully erosion.
Operators of clean cropped plantations assert that clean cropping is necessary
to achieve rapid growth of Christmas trees for an adequate return on invest-
ment.

Roadways covered by flood waters impede or prevent travel by Valley residents.
Persons who live in low lying areas often move their vehicles to higher ground
when they receive adequate advance warning of flooding.

Structures, both residential an 'd agricultural, are subject to water damage.
The level of damage occasionally includes structural damage. In addition, the
contents of the structures, such as home furnishings, appliances, and farm ma-
chinery, may also be damaged. Few Valley residents have elevated their homes
to a level adequate to protect against substantial flooding.

Agricultural fencing may be damaged by debris carried by flood waters, and
fields may be littered by stranded debris.

Sewage disposal throughout the Valley is by on-site drain fields. Under normal
conditions a high water table makes drain fields marginally effective. When
the Valley is flooded, sewage disposal drain fields are nonfunctional during
the flood and for days to weeks thereafter.

The following identification of chronic problem areas is based on reconnais-
sance field investigations conducted for this report, and on the reports of
Skokomish Valley residents. Naturally, the list will be incomplete, as we were
unable to interview all shoreline property owners in the Valley.

The South Fork and main stem from South Fork RM 3 downstream to about main stem
RM 5.5 is aggrading. The secondary effects of aggradation is generalized
streambank erosion which is notably severe in certain locations. These loca-
tions of severe bank erosion are identified in the following paragraphs.

At South Fork RM 1.8, bank erosion has cut to within 50 feet of Skokomish Val-
ley Road, and threatens to undermine the roadway within a few years.

An eroding right bank between RM 8.1 and 8.3 in the vicinity of Skokomish Com-
munity Church has cut to within 50 to 70 feet of Skokomish Valley Road.

An eroding left bank at RM 3.5 affects Skokomish tribal trust land. The cause
of the erosion may due to the normal meandering process, or may be aggravated
by streambank protection projects carried out upstream over the years.

PRIOR FLOOD CONTROL INVESTIGATIONS AND PLANS
Three prior investigations of flooding and potential flood control measures
have been carried out on the Skokomish River: (1) in the early 1940s by the US
Army Corps of Engineers (Dunn, 1942), (2) in the late 1950s and early 1960s by
the US Soil Conservation Service (Cowley, 1958; SCS file correspondence), and
(3) in the late 1960s as a part of the Puget Sound and Adjacent Waters (PSAW)
Study carried out by the Pacific Northwest River Basins Commission (Flood Con-
trol Technical Committee, 1970).

These investigations all use the basic benefit:cost analysis premise: the aver-
age annual equivalent benefits from a project must exceed the average annual
equivalent costs of the project. That is, the benefits divided by the costs
must exceed 1.0 to be a viable project.

None of these studies appear to have addressed the secondary costs of implemen-
tation, that is, the costs of damage to the anadromous fishery as a result of
instream or streamside construction effects on fish habitat.

US ARMY CORPS OF ENGINEERS, 1942
In response to chronic and catastrophic flooding of the Skokomish Valley agri-
cultural lands during the 1920s and 1930s, the Corps of Engineers initiated a
study and issued their report to Congress in 1942. A summary of their findings
follows.

The average annual flood damages, not including land erosion, had been about
$13,400/year during the 16 year period since construction of Cushman Dam in
1926. Since 1931, erosion of approximately 37 acres of farmland at several lo-
cations along the south bank of the channel had occurred, at the rate of about
3.4 acres a year. This loss was largely of developed farmland, thus the value
of land lost annually was computed to be $600. The total annual combined cost
was $14,000/year.

During this pre-World War II period, the agricultural economy of the Valley was
based on dairy farming on the larger ownerships, and on gardening, "truck farm-
ing," and subsistence farming on the smaller holdings. Protection of the de-
veloped farmland from flooding would have permitted more intensive cultivation
and the growing of higher value crops, but it was judged that the distance from
a major market would limit the acreage that would be intensively cultivated.

Additionally, if flooding were prevented, the remaining undeveloped land could
be cleared and developed agriculturally (at a cost of about $90/acre) and
thereby potentially attaining the same value ($168/acre) as the other agricul-
tural land in the valley. The potential value ($168/acre) less the base value
($61/acre) and the cost of development ($90/acre) would leave a residual
$17/acre in increased value attributable to flood control, or a total of
$38,964.

Three protective measures were evaluated: levees, channel improvements, and up-
stream storage. Protection by levees would have required the construction of
over 14 miles of levees, protected from erosion on the riverside by heavy
riprap. The construction cost estimate was $225,000. Annual maintenance, am-
ortization, and interest charges on such a project would have amounted to about
10 percent of th e construction cost, or 22,500 annually, which is 160 percent

of the yearly benefits ($14,000 in average annual flood damage costs).

Because of the vast amount of gravel moved by the river in flood stages, an im-
proved channel could not be maintained in the middle and upper reaches of the
valley, except at excessive cost. No actual costs were computed.

Likewise, the cost of a flood control storage reservoir exceeded the expected
benefits. No actual costs were computed.

Bank erosion, which caused an average annual cost of $600 in lost land could
have been prevented by revetment or riprap. The estimated cost of either a
brush mat revetment or rock riprap would have been $65,000. The annual cost of
such a project based on a 25 year life, would have been $4,300, which exceeds
the annual benefits by 360 percent.

As a result of these findings, the Corps of Engineers recommended to Congress
that no flood control project be approved for th-e Skokomish River.

US SOIL CONSERVATION SERVICE, 1964
Periodic reconnaissance studies by US Soil Conservation (SCS) staff (princi-
pally Cowley, 1958) and internal SCS reports on flooding in the Skokomish Val-
ley culminated in an internal memorandum and summary benefit:cost study in 1964
(memorandum, J. A. Paulson to L. F. Kehne, 3 September 1964).

The Cowley (1958) report identified estimated annual flood damages in the Sko-
komish Valley to total $69,316 based on the following breakdown: annual damage
to 52 farms, $45,616; annual damage to County roads, bridges, etc., $15,000;
annual damage to logging industry, $7,200; annual damage to p'ublic utility dis-
trict, $1,500. The identified watershed flood problems included: (1) stream-
bank erosion; (2) sand and gravel deposition on pastures; (3) flood water dam-
age to residences, farm buildings, machinery, and stored feed; (4) damage to
transportation and public utility structures; (5) the cost to timber companies
in transportation delays; and (6) excessive deposition on oyster beds on the
Skokomish delta.

The proposed solutions included channel excavation, streambank diking and
riprapping, bridge alterations, and installation of drainage floodgates. The
estimated cost was nearly $3 million. Amortized over 100 years at 3-1/8 per-
cent, and including operation and maintenance expenses, the total average an-
nual equivalent cost was $117,575. Balanced against an estimated average an-
nual benefit of $85,000, the benefit:cost ratio of 0.72 was below 1.0, thus the
project could not qualify for funding.

PUGET SOUND AND ADJACENT WATERS (PSAW) STUDY, 1970
The PSAW Flood Control Technical Committee (1970) found flooding of the Skoko-
mish Valley to be frequent, but because the land was used almost exclusively
for pasture, the resulting average annual damages were estimated to be $27,000
at 1966 prices. Voluntary operation of Cushman Reservoir by the City of Tacoma
for partial flood control on the North Fork had reduced the frequency and se-
verity of overbank flooding in the main stem.

Three alternative flood control measures were evaluated, a storage reservoir on

the South Fork, levees along the main stem and north and south forks up to
river mile 10, and streambank protection. As summarized in Table 5.2, none of
the alternatives had a favorable benefit:cost ratio.

Table 5.2. FLOOD CONTROL ALTERNATIVES, PSAW STUDY, 1970.

-------------------------------------------------------------------------------
Flood Control Alternative Estimated Estimated Estimated
@Development Annual Annual Benefit
Cost, 1968 $ Cost, $ 1966 $

-------------------------------------------------------------------------------
South Fork Storage Reservoir 22,500,000 1,100,000 25,000
Levees, RM 0.0 to 10.0 900,000 100,000 25,000
Bank protection 300,000 17,000 1,200
Source:-Flood-Control-Technical-Committee,-1970 ---------------------------------

The Flood Control Technical Committee recommended implementation of flood plain
zoning and management measures for the entire flood plain to limit future de-
velopment and to minimize future flood damages.

SUMMARY
Flood control works in the Skokomish Valley have been concentrated on gravel
and debris removal from the river and its tributaries to maintain flows,
streambank riprapping and revetment placement for bank protection, and bridge
and culvert construction. This work has been carried out by individuals using
private funding, and by Mason County under cost share programs with the state
of Washington. No significant amount of floodproofing of residences or agri-
cultural buildings has been done. Little is known regarding the economic im-
pact of annual flooding.

Three prior investigations of flooding and potential flood control measures
have been carried out on the Skokomish River: the first in the early 1940s by
the US Army Corps of Engineers, the second in the late 1950s and early 1960s by
the US Soil Conservation Service, and the third in the late 1960s as a part of
the Puget Sound and Adjacent Waters (PSAW) Study carried out by the Pacific
Northwest River Basins Commission.

However, these investigations all focused on structural solutions to flood pro-
tection for the valley. None addressed nonstructural solutions such as flood-
proofing individual structures, or emergency warning and evacuation systems.

Chapter 6

SKOKOMISH BASIN REGULATORY PROGRAMS

INTRODUCTION
Various regulatory programs affect both the need for flood protection measures,
as well as the manner in which structural approaches to flood protection may be
carried out. Unrestricted development of a flood plain will increase the po-
tential damage resulting from flooding, and thus the need for flood protection
measures; properly conceived and implemented land use regulations can temper
excessive public and private development investment in flood plains, and thus
the need to expend public funds for flood protection and disaster relief.
Structural flood protection, like any other construction or development, must
comply with the criteria of laws regulating instream and shoreline construc-
tion.

LAND USE AND SHORELINE REGULATION
L6cal land use and shoreline regulations which can affect development in flood
hazard areas, and which can also affect flood control measures, include build-
ing codes, zoning ordinances, comprehensive plans, shoreline master programs,
and flood control regulations. Each local jurisdiction will approach land and
shoreline use regulation in their own way, to meet their own needs. Mason
County's approach is outlined below.

MASON COUNTY BUILDING CODE
Building codes may be used to alert home builders and home owners to the haz-
ards of occupying floodplains, or in conjunction with a zoning ordinance may be
used as a check point to assure that required flood proofing of new construc-
tion occurs.

Mason County has adopted the Uniform Building Code (UBC) which contains no spe-
cial regulations regarding construction in flood plains. The County Building
Department does use the soil load bearing strength provisions of the UBC to
regulate proposed development in wetlands, bogs, peatlands, etc.

MASON COUNTY ZONING AND COMPREHENSIVE PLAN
Zoning and comprehensive plans may be used to specially regulate development,
particularly residential development, in hazardous areas such as flood plains
or landslide zones. The special regulation may take the form of development
density limitations, or of outright prohibition of certain forms of development
in certain areas. The identification of special hazard areas may be done by
establishing and mapping special zones, or may be through overlay zoning over
the basic zoning map.

Mason County has no county zoning ordinance.

The County Comprehensive Plan now in effect was adopted in 1973. This Plan
contains broad goals for Mason County land use and generalized policies to
guide decisions in attaining those goal's. The Plan contains no specific guide-
lines or land use density recommendations as the map accompanying the draft

plan was not adopted. Updated county-wide comprehensive plans were developed
in 1979 and again in 1982. Neither updated plan was officially adopted by the
County Commissioners. Presently, Mason County proposes developing an updated
comprehensive plan using the subarea planning process. There is no completion
schedule for the proposed subarea planning.

The comprehensive plan proposed in 1982 identified the Skokomish Valley as
Natural Hazard Area due to flooding, and the adjacent canyon slopes as a
Natural Hazard Area due to unstable slopes. The comprehensive plan would have
discouraged residential and commercial development in floodplains, and would
have encouraged land uses "such as agriculture, recreation, or very low density
residential to protect the public health, safety and welfare."

The special goals and policies recommended for the Olympic/Skokomish (Hoods-
port) Subarea include forestry, agriculture, aquaculture, tourism and recre-
ation, and overall policies, but nothing regarding land use in the Skokomish
Valley.

MASON COUNTY SHORELINE 14ASTER PROGRAM
The Mason County Shoreline Master Program (MCSMP) was first approved by the De-
partment of Ecology on 6 August 1975. The most recent amendment was approved
on 16 October 1984.

Local shoreline master programs (SMPs) are mandated by the state Shoreline Man-
agement Act (SMA; Chapter 90.58 RCW) which has as its central intent:

. . . to insure the development of these shorelines in a manner
which, while allowing for limited reduction of rights of the public
in navigable waters, will promote and enhance the public interest.
This policy contemplates protecting against adverse effects to the
public health, the land and its vegetation and wildlife, and the wa-
ters of the state and their aquatic life, while protecting generally
public rights of navigation . . .

Thus, the broad purposes of.the SMA is to manage public and private development
in the shoreline zone, while protecting the public's 'interest in public re-
sources such as water, fish and wildlife, and the habitat that supports those
species. The SMA is implemented by local government under the oversight of the
state Department of Ecology. The SMA applies to waters of the state: all ma-
rine waters, all streams with an average annual fl-ow of 20 cfs or greater, and
all lakes with a surface area of 20 acres or greater. The SMA is a state law
which is implemented at the local government level.

The SMA requires a permit for "substantial development" in shorelines of the
state. With certain exceptions, substantial development is anything with a
value of $2,500 or more (RCW 90.58. 140). "Shorelines" includes all waters of
the state, plus adjacent lands within 200 feet of the ordinary high water line ,
all associated wetlands, and, in counties so designating, the 100-year flood
plain (RCW 90.58.030). The Mason County SMP defines shorelines as the 200 foot
zone, plus associated wetlands which includes "marshes, bogs, swamps, flood-
ways, river deltas, and flood plains associated with the streams, lakes, and
tidal waters which are subject to the provisions of the Act and this ordinance"
(MCSMP 7.08.250). Essentially the entire Skokomish Valley is a 100 year flood

plain, thus a substantial development permit is necessary for any regulated
construction in the valley.

Mason County will propose amendments to the SMP which will in part redefine as-
sociated wetlands as the "floodway plus a 200 foot setback zone," rather than
the current "flood plains" definition. Adoption by Mason County and approval
by the Department of Ecology is anticipated in late 1987.

Special provisions of the SMA apply to Shorelines of Statewide Significance
(SSS; RCW 90.58.020) which are defined for streams west of the Cascade Range
crest as having a mean annual flow of 1,000 cfs or greater (RCW 90.58.030 [2]
[e] [v]). Regarding development on Shorelines of Statewide Significance, the
Act states:

The legislature declares that the interest of all the people shall be
paramount in the management of shorelines of state-wide significance.
The department (of ecology], in adopting guidelines for shorelines of
state-wide significance, and local government, in developing master
programs for shorelines of state-wide significance, shall give pref-
erence to uses in the following order of preference which:
(1) Recognize and protect the state-wide interest over local in-
terest;
(2) Preserve the natural character of the shoreline;
(3) Result in long over short term benefit;
(4) Protect the resources and ecology of the shoreline;
(5) Increase public access to publicly owned areas of the shore-
lines;
(6) Increase recreational opportunities for the public in the
shoreline;
(7) Provide for any other element as defined in RCW 90.58.100
deemed appropriate or necessary.

The Skokomish River is a Shoreline of Statewide Significance downstream of the
confluence of the North Fork and the South Fork (WAC 173-18-270 [26]). The Ma-
son County SMP contains no special provisions regarding SSS (Chapter 7.24.010),
thus the general provisions of the SMA provide primary guidance. However, the
Mason County SMP also states that in recognition "that all shoreline areas of
Mason County are of equal importance to Mason County residents and the state as
a whole; all shorelines designated in this ordinance shall be considered as be-
ing of state-wide significance, whether or not they are so designated in the
Act" (MCSMP 7.04.032).

Because federal government reservations are generally exempt from the SMA, the
SMA does not apply to the shorelines of the Skokomish River within the Skoko-
mish Indian Reservation. This exception applies only to the left bank of the
river which lies within the reservation and forms its southerly and easterly
boundary.

The Mason County SMP identifies four shoreline environment designations --
Natural, Conservancy, Rural, and Urban -- in accordance with the SMA regulatory
guidelines for development of local SMPs (WAC 173-16-040). Shoreline environ-
ments are mapped and defined to address relative needs for shoreline manage-
ment. The Mason County SMP designates the ma.in stem of the Skokomish as a Ru-
ral Shoreline Environment; the North Fork, South Fork, and Vance Creek within

the primary study area are designated as Conservancy Shoreline Environment.

The principal development activities in the Skokomish Valley which are
regulated by the Mason County SMP include:
7.16.010 Agriculture, pesticides, and fertilizers;
7.16.080 Residential development; and
7.16.180 Shoreline protection.

Agricultural and residential regulations are summarized in Table 6.1; shoreline
protection regulations are described in detail below.

Agricultural practices, as a practical matter, cannot be effectively regulated
through the local SMP. No permits are necessary to carry out agricultural
practices, thus the SMP provisions for agricultural practices are advisory.
Feedlots however, being a form of land development, can be regulated under an
SMP. There are no feedlots in the Skokomish Valley, though some valley farmers
keep dairy or beef cattle.

Residential development (but not the construction of individual homes) requires
a Shorelines Substantial Development Permit. The Mason County SMP regulates
only residential setbacks from the shoreline, and not residential densities or
types. New home construction in the Valley is infrequent, and no residential
developments (e.g. subdivisions) have been proposed since the SMA was enacted.

Flood control and streambank protection measures, to the extent they are
regulated by the Mason County SMP, come under the provisions of Chapter
7.16.180, Shoreline Protection, which states:

A. Urban Environment
1. Shoreline protection measures which might result in chan-
nelization should be closely evaluated prior to construc-
tion.

2. Riprapping and other bank stabilization measures shall be
designed, located, and constructed with intent to preserve
natural character of the area.

3. The use of automobile bodies for shoreline protection shall
be prohibited.

B. Rural Environment
1. All Urban Environment use regulations shall apply in this
environment.
C. Conservancy Environment
1. All Urban Environment use regulations shall apply in this
environment.

2. Construction designed to protect the shoreline should be
permitted only when such construction is necessary for the
protection of life and property.

3. Bank stabilization by the planting of vegetation shall be
permitted.

D. Natural Environment

1. All Conservancy Environment use regulations shall apply in
this environment.

2. Shoreline protection measures shall be compatible with the
Natural Environment.

By policy, the Mason County Department of General Services considers diking re-
quiring 500 CY (cubic yards) of fill material to be valued at $2,500.00, thus
diking projects requiring 499 CY of fill material (or less) are categorically
exempt from requirements for a Shoreline Substantial Development Permit.

Table 6.1. AGRICULTURAL AND RESIDENTIAL SHORELINE REGULATIONS.
Activity ----------------- Rural-Environment --------- Conservancy-Environment ------
-------------------------------------------------------------------------------
Agriculture
Tillage patterns Tillage which permits large quantities of soil and
sediments to enter waterways is prohibited.

Feedlots and stockyards Prohibited in floodways. Prohibited throughout the
Conservancy Environment

Buffers A buffer of permanent vegetation is required between
tilled areas and waterways to retard surface runoff.

Residential
Setbacks Fifteen feet from ordinary high water with no
exceptions allowable.

Cluster development Discouraged. Discouraged.

General None. Greater emphasis on protec-
tion of biophysical limita-
tions and aesthetics.

------------------------------------------------------------------------------
Source: Mason County Shoreline Master Program, 7.16.010 and 7.16.080.

The Mason County SMP is administered by:
Mason County Department of General Services
Mason County Courthouse Annex 1
Shelton, Washington 98584

State oversight of Shorelines Substantial Development Permits is administered
by: Management Section
Shorelands & Coastal Zone Management Program
Washington Department of Ecology
Olympia, Washington 98504

RESOURCE MANAGEMENT
Resource management regulations are intended and designed to protect public re-
sources such as water, fish, and wildlife, while allowing reasonable exercise
of private property rights. Because structural flood protection measures are
usually carried out within the stream or nearby in the shoreline zone, they
have the potential to damage public resources.

HYDRAULIC PROJECT APPROVAL
The Hydraulic Project Approval (HPA) is issued by the state department of
Fisheries or Game under the authority of the Washington Hydraulic Code (RCW
75.20.100) which requires the departments to regulate activities within the ma-
rine and fresh waters of the state. The Department of Fisheries exercises ju-
risdiction over marine waters. The two agencies share jurisdiction over fresh
waters, though one agency will assume lead status over a specific fresh water
body. The Department of Fisheries exercises jurisdiction over the Skokomish
River. Regulation is implemented in accordance with the Hydraulic Code Rules
(Chapter 220-110 WAC).

Therefore, any shore protection works, such as dikes constructed waterward of
the line of ordinary high water, or instream work such as gravel removal, con-
ducted in the Skokomish Valley require an HPA.

The primary function of the Hydraulic Code is to protect the state's fisheries
resources, including spawning and rearing habitat. Thus the rules for gravel
removal (WAC 220-110-140) limit the removal to gravel two feet above the cur-
rent water level, prohibit the leaving of potholes, and require a maximum gra-
dient on the excavated surface of two percent. The rules for bank protection
work (WAC 220-110-050) limit such construction to stream banks actually dam-
aged.

An HPA is required for both new construction and repair of old or damaged bank
protection works. An approved HPA will ordinarily carry strict limitations on
the time of year during which construction activities may be carried out. This
is necessary to protect certain fish populations during critical phases of
their life cycle.

HPAs for the Skokomish River are administered by:
Habitat Management Section
Washington Department of Fisheries
3939 Cleveland Avenue
Tumwater, Washington 98504

DEPARTMENT OF THE ARMY PERMIT
The US Army Corps of Engineers (Corps) is required to regulate discharges of
dredged and fill material into waters of the United States and associated wet-
lands under Section 404 of the Clean Water Act. This regulatory charge in-
cludes shore protection structures and any associated earthmoving and landfill-
ing. The Corps is also required to regulate any construction within navigable
waters under Section 10 of the Rivers and Harbors Act of 1899. The Corps has
developed a consolidated permit application and review program for their re-
sponsibility under both laws, known as the Department of the Army Permit.

Therefore, any shore protection structures constructed waterward of the line of
ordinary high water (or within an associated wetland) will require a Department
of the Army Permit.

Certain minor shore protection projects may come under the Corps' nationwide
permit program, for which no formal permit application is required. However,
notification of the Corps is required for certification of exemption from full
permit application and processing requirements. Minor shore protection works
eligible for the nationwide permit program are still required to meet certain
minimal design and construction specifications. An exemption to the require-
ment for a full permit application and processing under the nationwide permit
program may be obtained if the proposed shore protection work complies with the
following criteria (33 CFR 330.5 [a] [13]):

1. the-proposed shore protection work is less than 500 feet in length;

2. the project is necessary for erosion prevention;

3. the filling within waters of the United Stated is limited to less than one
cubic yard per running foot of shore protection;

4. no material is.placed in excess of the need for shore protection;

5. no material is placed in a wetland;

6. no material is placed so as to impair surface water flow into or out of a
wetland;

7. only clean fill free of waster metal products, organic materials, un-
sightly debris, etc., is used; and

8. the proposal is for a single, complete project.

The Department of the Army Permit program is administered by:
Regulatory Functions Branch
Seattle District
US Army Corps of Engineers
P. 0. Box C-3755
Seattle, Washington 98124

WATER QUALITY CERTIFICATION
The Washington Department of Ecology administers the state Water Pollution Con-
trol Act Chapter 90.48 RCW) in accordance with the Water Quality Standards for
Waters of the State of Washington (Chapter 173-201 WAC).

Stream bank protection and instream gravel removal has the potential to create
temporary instream turbidity (sedimentation) in excess of state water quality
standards during the construction period. The Water Quality Standards-provide
for short term modifications of,the standards "when necessary to accommodate
essential activities, respond to emergencies, or to otherwise protect the pub-
lic interest" (WAC 173-201-035 (8] [e]).

Stream bank protection and instream gravel removal projects require a Water

Quality Certification including a short term modification of pertinent water
quality standards., Each such certification is reviewed and issued on an indi-
vidual basis as an administrative or@er, and includes specific limitations on
how and when construction activities may be carried out. For projects which
also require a Department of the Army Permit, application for a Water Quality
Certification should be made to:

Environmental Quality Section
Southwest Regional Office
Washington Department of Ecology
7272 Cleanwater Lane
Olympia, Washington 98504

For projects not requiring a Department of the Army Permit, application for a
Water Quality Certification should be made to:

Environmental Review Section
Washington Department of Ecology
Olympia, Washington 98504

FLOOD CONTROL AND FLOODPLAIN MANAGEMENT
There are a number of programs which relate to flood control or flood plain
management. Some are intendedito regulate certain activities (e.g. land use)
to limit the effects of flooding. Others are nonregulatory programs intended
to coordinate and finance public flood control measures.

NATIONAL FLOOD INSURANCE PROGRAN
The National Flood Insurance Program is described in detail in a publication
available from the Shorelands and Coastal Zone Management Program of the Wash-
ington Department of Ecology (F7oodplain mana_qement handbook for 7oca7 adminis-
trators; Floodplain Management Section, 1986). The following is a summary of
the program.

The National Flood Insurance Program (NFIP) was established in 1968 to make
flood insurance available for residential and nonresidential structures. Prior
to 1968 flood insurance was not available at costs affordable to most home own-
ers or small businesses. The NFIP has two central purposes. First, by making
flood insurance available, Congress felt that it.could alleviate the financial
burden and general economic distress resulting from both chronic and disastrous
flooding, and which affects individuals, local economies, and the nation as a
whole.

Second, Congress also had the goal reducing the fiscal drain on the national
Treasury of having to provide flood disaster relief and remedial flood control
works for-persons who have chosen to live in or otherwise occupy flood plains.
Accordingly, Congress linked the availability of low cost flood insurance to
the local implementation of land use management and construction practices de-
signed to limit future development in flood plains and thus future flood dam-
ages. Thus as past unsound land use patterns and construction practices cease
and are replaced with patterns and practices in conformance with the criteria
of the NFIP for insurance eligibility, the drain on the national Treasury for
flood disaster relief and flood control work will lessen.

The basis of operation of the NFIP is an agreement between a city or county
government, a community in NFIP terminology, and the Federal Emergency Manage
ment Agency (FEMA), the federal agency which administers the program. When
FEMA identifies a community as being "flood prone" and the community chooses to
participate in the program by adopting and enforcing flood plain management
measures, the community, in exchange, becomes eligible to have flood insurance
coverage made available. The community must adopt and enforce flood plain man-
agement regulations in accordance with the minimum criteria of FEMA. The com-
munity may also adopt more stringent regulations if it desires.

Under the "Emergency Phase" of the program, minimal insurance coverage is made
available in limited amounts at low-cost, subsidized rates. Increased amounts
of flood insurance coverage become available at actuarial (unsubsidized) rates
when the community converts to the "Regular Phase" of the program. Conversion
to the Regular Phase occurs following completion of a detailed Flood Insurance
Study by FEMA, and adoption of additional flood plain land use and construction
practices regulations by the community. The actual flood insurance policy is
written by any licensed agent or broker at the choice on the property owner.

Participation in the NFIP by local communities is voluntary, but most communi-
ties have chosen to participate to gain the benefits of low cost flood insur-
ance for local residents, taxpayers, and small businesses.

Mason County is presently in the Emergency Phase of the program. FEMA has re-
cently completed its detailed study which is still in review and is described
in the following section.

FEMA FLOODWAY MAPPING, 1987
The Federal Emergency Management Agency (FEMA), under the National Flood Insur-
ance Program (NFIP) issued Floodway (Flood Boundary and Floodway) Maps and FIRM
(Flood Insurance Rate Maps) maps for Mason County in 1983. Subsequently, FEMA
restudied Mason County, and reissued draft Floodway and FIRM maps in 1987 dur-
ing the preparation of this draft Skokomish River CFCMP.

This mapping indicates that essentially the entire Skokomish Valley lies within
the 100-year floodplain of the Skokomish River.

Flood plain management and flood insurance programs use certain terms to de-
scribe specific portions of the flood plain which have specific meanings. A
typical stream cross-section and illustration of those terms is depicted in
Figure 6.1.

The "stream channel" is the part of the stream way which carries the normal low
flows as discussed in the Introduction to this Chapter.

The "100-year flood plain" is that part of the stream way which historically
has carried flood flows of a specific magnitude, and provided temporary flood
water storage. At lower elevations in western Washington it typically has a
forest of Red Alders, Black Cottonwoods, Oregon Ash, willows, or other de-
ciduous trees, in comparison to the conifer-forested uplands. The term
"100-year flood" was unfortunately a misleading choice of terminology, as it
implies a regular cycle of high intensity storms. Actually, the term 100-year
flood means one chance in 100 of a specific flood volume each year, or a one

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Figure 6.1 Flood Plain Schematic Cross Section
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percent chance of occurrence. Similarly, the 50-year flood has a two percent
chance of occurrence each year. It is possible, though highly improbable, to
have a 100-year flood two years in a row, or even twice in a year.

The "floodway fringe" and "floodway" are terms identifying portions of the
flood plain where encroachment is allowed and disallowed.

It is important to remember that the FEMA program is a flood insurance program,
not a flood plain regulatory program. However, for a community to remain
qualified for enrollment in the flood insurance program, certain criteria must
be met through local government flood plain regulation.

FEMA requirements allow filling and development of the floodway fringe, and
most local governments adopt the FEMA requirements without change since they
are a minimum requirement. Filling and development in the floodway fringe
eliminates a portion of the flood water storage capacity of the flood plain,
causing a rise in flood water elevation. The FEMA program is designed to ac-
count for this: the dashed river surface line A-B in Figure 6.1 represents the
surface elevation of the 100-year flood under "natural" conditions; the solid
line C-D represents the surface elevation of the 100-year flood under full de-
velopment encroachment of the floodway fringe. The width of the floodway
fringe is fixed by FEMA to allow a maximum one foot rise (surcharge) in the
surface elevation of the 100-year flood.

FLOOD CONTROL ZONE ACT
The Flood Control Zone Act was first enacted by the state legislature in 1935
for the "alleviation of recurring flood damages to public and private property,
to the public health and safety, and to the development of the natural re-
sources of the state . . ." (RCW 86.16.010). The Act originally specified
state regulatory authority over designated flood control zones, including the
authority to regulate construction and planning within flood plains and
floodways (RCW 86.16.020, 025).

In June 1987, the Legislature enacted substantial changes to the Act (ESB
5556), shifting basic regulatory authority from the state to local government,
eliminating the designated flood control zones, and extending authority of the
act to the entire state, not just the designated flood control zones. The
state retained oversight authority over the actions of local governments in
implementing the new Act. The Department of Ecology provides technical assis-
tance to local governments, and must approve locally prepared floodplain man-
agement programs.

Floodplain management programs must be consistent with the regulatory require-
ments of the National Flood Insurance Program whether or not the local commu-
nity is enrolled in the NFIP or not. Local floodplain management programs must
include a prohibition of construction or reconstruction of residential struc-
tures with designated floodways. The Act directs the Department of Ecology to
11assume regulatory authority for floodplain management activities in the event
of failure by the local government to comply with the requirements of" the Act.

At this time (July 1987), Ecology has not yet promulgated new rules for the
implementation of the revised Act.

MASON COUNTY FLOODPLAIN REGULATIONS
Mason County has not yet adopted any floodplain management regulations. The
matter is presently under consideration. If Mason County is to continue to
participate in the National Flood Insurance Program, a floodplain management
ordinance acceptable to FEMA must be adopted.

COORDINATION
There are no institutionalized programs for comprehensive coordination of land
use and flood control regulations or permit processing at either the state or
local government level. Informal coordination occurs between the state depart-
ments of Ecology and Fisheries regarding comprehensive flood control management
planning.

Four permits are potentially necessary to carry out a structural flood control
work. A federal Department of the Army Permit, a consolidation of the Section
10, Rivers and Harbors Act, and Section 404, Clean Water Act permits, is neces-
sary for work carried out in navigable waters, waters of the United States, and
adjacent wetlands. A state hydraulic project approval (HPA) is necessary from
the state departments of Fisheries and/or Game for work in or near fish bearing
waters. A local Shoreline Substantial Development Permit, under the state
Shoreline Management Act, is necessary for work in and within the wetlands ad-
jacent to streams with an average annual flow of 20 cfs or greater. A Flood
Control Zone Permit under the Flood Control Zone Act is necessary for new con-
struction in the floodway, as well as any flood control work or maintenance of
existing flood control structures.

The state's ECPA (Environmental Coordination Procedures Act) process is volun-
tarily available to permit applicants through the Department of Ecology's Envi-
ronmental Review Program for coordination of state permits, but this does not
include coordination of federal permits. Coordination is considered necessary
to avoid contradictory conditions of permit approval by different agencies with
different regulatory mandates.

Interagency Stream Corridor Management Guidelines were promulgated in 1985 as
an interagency memorandum of understanding (MOU) between the Washington depart-
ments of Game, Fisheries, and Ecology, the Washington Conservation Commission,
and the US Soil Conservation Service. The Guidelines establish a procedure for
interagency cooperation and coordination in the planning, designing, and imple-
menting of structural and nonstructural works and activities within stream cor-
ridors, including permit review. The MOU established an ongoing Stream Cor-
ridor Committee to carry out the intents of the MOU. The contact persons under
the MOU for the Skokomish River basin are:

Department of Game:
Regional Habitat Biologist
Region 6
905 East Heron
Aberdeen, WA 98520

Department of Fisheries:
Regional Habitat Manager
Habitat Management Section
Washington Department of Fisheries
3939 Cleveland Avenue
Tumwater, Washington 98504

Department of Ecology:
Flood Control and Water Quality:
Southwest Regional Office
Washington Department of Ecology
7272 Cleanwater Lane
Olympia, Washington 98504

Shoreline Management:
Management Section
.Shorelands and Coastal Zone Management Program
Washington i)epartment of Ecology
Olympia, WA 98504

Mason County Soil Conservation District:
Inactive; contact:
District Conservationist
Thurston County Soil Conservation District
816 East 5th Street
Olympia, WA 98501

US Soil Conservation Service:
Olympia Field Office
816 East 5th Street
Olympia, WA 98501

SUMMARY
Various regulatory programs affect both the need for flood protection measures,
as well as the manner in which structural approaches to flood protection may be
carried out.

Building codes may be used to alert home builders and home owners to the haz-
ards of occupying floodplains, or in conjunction with a zoning ordinance may be
used as a check point to assure that required flood proofing of new construc-
tion occurs. The Mason County Building Code contains no special regulations
regarding construction in flood plains.

Zoning and comprehensive plans may be used to specially regulate development,
particularly residential development, in hazardous areas such as flood plains
or landslide zones. The County Comprehensive Plan in effect was adopted in
1973. This Plan contains broad goals for Mason County land use and generalized
policies to guide decisions in attaining those goals. The Plan contains no
specific guidelines or land use density recommendations.

Local shoreline master programs (SMPs) are mandated by the state Shoreline Man-
agement Act (SMA; Chapter 90.58 RCW). Residential development (but not the

construction of individual homes) requires a Shorelines Substantial Development
Permit. The Mason County SMP regulates only residential setbacks from the
shoreline, and not residential densities or types. New home construction in
the Valley is infrequent, and no residential developments (e.g. subdivisions)
have been proposed since the SMA was enacted. The Mason County SMP regulations
of shore protection are mostly advisory.

The National Flood Insurance Program (NFIP) is a federal program instituted in
1968 to make flood insurance available to home owners and small business per-
sons. Participation in the NFIP by local communities is voluntary, but most
communities have chosen to participate to gain the benefits of low cost flood
insurance for local residents, taxpayers, and small businesses. Mason County
is presently in the Emergency Phase of the program.

The Flood -Control Zone Act was first enacted by the state legislature in 1935.
In June 1987, the Legislature enacted substantial changes to the Act (ESB
5556), shifting basic regulatory authority from the state to local government,
extending authority of the act to the entire state, not just the former desig-
nated flood control zones. The state retained oversight authority over the ac-
tions of local governments in implementing the new Act. The Department of
Ecology must approve locally prepared floodplain management programs. Flood-
plain management programs must be consistent with the regulatory requirements
of the National Flood Insurance Program whether or not the local community is
enrolled in the NFIP or not. Local floodplain management programs must include
a prohibition of construction or reconstruction of residential structures with
designated floodways. The Act directs the Department of Ecology to "assume
regulatory authority for floodplain management activities in the event of fail-
ure by the local government to comply with thd requirements of" the Act. At
this time (July 1987), Ecology has not yet promulgated new rules for the imple-
mentation of the revised Act.

Mason County has not yet adopted any floodplain management regulations. The
matter is presently under consideration. If Mason County is to continue to
participate in the National Flood Insurance Program, a flood hazard ordinance
acceptable to FEMA must be adopted.

The Skokomish Flood Control District was established in 1976 under the author-
ity of the Flood Control Zone Districts Act (Chapter 86.15 RCW). As a quasi
municipal corporation, Flood Control Zone Districts have taxing authority; the
Skokomish Flood Control District taxes property within the district at $0.50
per $1,000 assessed valuation.

There are no institutionalized programs for comprehensive coordination of land
use and flood control regulations or permit processing at either the state or
local government level. Four permits are potentially necessary to carry out a
structural flood control work: a federal Department of the Army Permit; a state
hydraulic project approval (HPA); a local Shoreline Substantial Development
Permit; and a Flood Control Zone Permit.

Chapter 7

ALTERNATIVE FLOOD CONTROL MANAGEMENT MEASURES

INTRODUCTION
Nationally, the general history of flood damage reduction has been one of a
steadily increasing awareness of the adverse secondary effects of earlier at-
tempts at localized flood control. In the past, the principal means of flood
control involved structural solutions such as diking or channelization. In
comparison with other rivers in the state, there has been relatively little
construction of structural flood control facilities along the Skokomish River.

The size of a stream or river bed, its width and depth, is created by the wa-
ters it carries. Streams "size themselves" to carry the water from the largest
flow volume normally occurring every year or two. Flows larger than those
typically occurring every year or two top the stream banks and flow downstream
in the flood plain. Thus the historical function of the stream bed is to carry
ordinary, low volume stream flows and the function of the flood plain has been
to carry larger flows and provide temporary storage of flood waters (Dunne &
Leopold, 1978). Occupancy of flood plains and their conversion to agricultural
and other land uses has created conflicts between man's desires for use of the
land and the land's historical methods of passing flood waters.

Nationwide, the earliest attempts at flood control were direct efforts to pass
the flood waters by as quickly as possible. Typically this was accomplished
through stream channelization which enlarged, straightened, and sometimes paved
the stream channel and/or stream banks. This caused degradation or elimination
of fish and wildlife habitat values in the vicinity of the chann'elized reach,
and a resultant decrease or loss of fish production. The flood water was
passed downstream, sometimes increasing the flood hazard for downstream land
owners. There has been no substantive stream channelization of the Skokomish
River, and what has occurred has mostly been incidental to other actions such
as highway or bridge construction.

Another widespread approach to flood control has been the construction of dikes
and levees along the stream bank. This protected the lands behind the dike,
but usually resulted in a loss of the flood storage reservoir value of the
flood plain, further resulting in an increased downstream flood hazard. An
emerging practice is to locate dikes back from the river bank, balancing the
protection of uplands values with the preservation of the flood plain's storage
reservoir values, while minimizing adverse impacts on downstream land owners.
Most of the dike and levee construction on the Skokomish has been small scale,
privately constructed facilities, poorly capable of resisting major flooding.

Flood storage reservoirs are constructed as an alternative or supplement to
stream channelization and diking. Some reservoirs are multipurpose in that
they are designed to provide for flood control, hydropower production, and ir-
rigation water storage. The reservoirs on the North Fork are single purpose hy-
dropower production facilities with little capacity for flood control under
current licensing conditions. However, because the Cushman projects divert
most of the North Fork flows to Hood Canal, they inadvertently do provide some
flood flow mitigation.

Structural solutions to flood control,'such as the above, are costly. In re-
cent years, benefit cost analyses have often shown it to be more cost effective
for the public to purchase the development rights to lands at risk from flood-
ing, than to purchase structural solutions to flood control for those private
properties.

Flood insurance programs, while not reducing flooding or providing structural
flood protection measures, do mitigate the effects of flooding for persons who
have chosen to occupy flood plains and to purchase flood insurance. The Na-
tional Flood Insurance Program (NFIP) is administered by the Federal Emergency
Management Agency (FEMA). The regulatory permit programs are administered by
local government, and are based on their own flood regulation ordinances.
These local ordinances must comply with the minimum requirements of the NFIP
regulations in order for the community to remain eligible. Any person in the
community may buy flood insurance from any insurance agent regardless of where
the buildings are located only if the community remains eligible and enrolled
in the program. Mason County is currently enrolled in the emergency phase of
the program, and will need to adopt a local ordinance in order to convert to
the regular phase of the program.

This chapter considers stream corridor management and flood control management
measures which have been conducted in the Skokomish Valley as a response to
historical and current damages as described in Chapter 5, Historic Flood Dam-
ages and Planning.

Potential nonstructural and structural measures, successfully practiced else-
where and applicable to property in the.Skokomish Valley are discussed. Al-
though the upper half of the Skokomish River watershed is within the Olympic
National Forest and therefore exempt from state and local regulations, private
lands within the National Forest are not. It is appropriate to consider cer-
tain flood control management measures for those upstream lands as well.

The summary of this chapter addresses additional information or studies which
will be needed prior to effective implementation of flood control management
measures.

Various measures are recommended for consideration by the Skokomish Valley
residents, Mason County, and the Skokomish Indian Tribe, as well as the Wash-
ington State through its various agencies. Technical assistance from the Fed-
eral Emergency Management Agency and the US Army Corps of Engineers can provide
a major contribution in implementing some floodproofing strategies. Also, a
combination of flood control management measures will be more effective than
any singular approach in reducing flood damages, especially if applied through-
out the watershed.

NONSTRUCTURAL MEASURES
Nonstructural measures consist of flood control alternatives which typically
affect one or two structures at a time or limit the location and type of devel-
opment occurring in floodprone areas. Human actions and behavior are the pri-
mary focus of nonstructural measures in reducing flood damages. Susceptibility
to flood damage and disruption, as well as the impact of flooding on indi-
viduals and the community, is reduced with effective implementation of
nonstructural measures.

INTRODUCTION
Susceptibility to flood damage and disruption can be reduced with nonstructural
measures. Uneconomic, undesirable, or unwise uses of the floodplain are
modified or eliminated. These measures include:

(1) Development policies
Location of sewers and utilities
Permanent evacuation
Renewal and redevel,opment
Open space
(2) Flood warning and forecasting
Evacuation plan
Flood watch
Flood warning system
(3) Disaster plans
Flood fighting, life saving
Emergency shelter
Medical and health
(4) Flood proofing
Modify buildings
Landfill
Elevate structures
(5) Land regulation
Zoning
Building codes
Subdivision regulation
Disclosure

Recovery from flooding and flood damages can be improved with nonstructural
measures which assist individuals and communities in their preparatory, sur-
vival, and recovery responses to floods. These measures include:

(1) Flood insurance maps
(2) Flood emergency operations
Flood fighting
Emergency health care and shelter
(3) Financial assistance for recovery
Low interest loans
Federal reconstruction assistance
Grants and disaster aid
(4) Tax adjustments

Structural measures are intended to modify flooding by artificially diverting
or retaining flood waters. These measures include:

(1) Flood diversions
(2) Channel alterations
(3) Dikes, levees, and floodwalls
(4) Dams and reservoirs
(5) Land treatment-

Floodplain management measures which have the potential of being alleviating
flood damages of the Skokomish Valley are discussed below.

FLOOD DAMAGE REDUCTION
(1) Development policies
Location of sewers and utilities
Permanent evacuation
Renewal and redevelopment
Open space
(2) Flood warning and forecasting
Evacuation plan
Flood watch
Flood warning system
(3) Disaster plans
Flood fighting, life saving
Emergency shelter
Medical and health
(4) Flood proofing
Modify buildings
Landfill
Elevate structures
(5) Land regulation
Zoning
Building codes
Subdivision regulation
Disclosure

DEVELOPMENT POLICIES

Evaluate siting of critical facilities and transportation: Relocate flood
warning and response communication center from Fire Hall to an area safely out
of the floodway and possibly out of the floodplain.

Evaluate current road alignment and'elevation. Alternative emergency escape
routes should be identified and established.

FLOOD WARNING AND FORECASTING

Evacuation or flood preparedness plans: Flood preparedness plans are a neces-
sary part of an effective flood warning system. Emergency actions in the case
of flooding should be established in advance to enable residents and the
various response services to best use the limited response time. These ac-
tivities can include establishing a communication and operation center for re-
sponse teams, notifying responsible officials and volunteers, evacuation
routes, and arranging temporary shelter. Residents can take a series of ac-
tions which will limit or reduce damage to property.

Residents: Each resident within the flood prone area of the Skokomish Valley
should have a list of early actions to be taken in anticipation of flood situa-
tions. Regular practice drills would assist in effectively responding in case
of an emergency or short notice. The following list of precautions is taken

from the F7ood Emergency and Residentia7 Repair Handbook (FEMA, 1986):

* Investigate the feasibility of purchasing flood insurance.
* Identify items to be evacuated with you.
* Prepare a checklist of emergency supplies and equipment for combatting
flood waters such as rope, plastic bags, sand bags, sump pump, buckets.
* List items to be relocated to a safer place in the order of their prior-
ity.
* Identify vulnerable areas where sandbags should be placed.
* Provide a circuit breaker or fuse chart with a list of those circuits to
be disconnected in a flood emergency.
* List locations and emergency turnoff instructions for main gas, water,
fuel tank, and sewer lines.
* Tie up a boat where it is readily available but not subject to damage.
* Write instructions for installing temporary shoring, bracing, or shear
wall supports.
* Provide instructions for opening and closing doors and windows at various
flood levels. Describe location of stored closure panels.
* Know destination and route to your evacuation point.
* List telephone number of a person to be notified that you are evacuating
and later that you have arrived safely. This provides knowledge that your
home does not have to be checked for emergency evacuees and also the sig-
nal to notify authorities if you are unable to reach your destination.

Loca7 f7ood warning systems: To date, there has been no formal flood warning
system available to the residents of the Skokomish Valley. Warning systems
forecast the intensity and timing of floods to provide the community adequate
time to take pre-planned actions which protect life and property and preventa-
tive measures to minimize damage throughout the flood event..

Fire District No. 9 has the primary responsibility for notifying and evacuating
residents in flood situations. Currently, the district does not have a formal
system for flood alerts or a flood preparedness plan.

Flood preparedness plans should be practiced and coordinated with all respon-
sible agencies and municipalities. A system should be developed whereby the
Fire District receives flood warnings and relays the information quickly to af-
fected persons. The Fire Hall is presently located in the Skokomish River
floodway. Headquarters for such a communication center should be located in an
area which is safe from.flooding.

Mason County's emergency response plan is general and does not prescribe an
evacuation plan or other specific flood fighting measures.

The City of Tacoma and residents of the community have been discussing the need
to install a warning system in the event of a dam failure at their Lake Cushman
facility and the most effective method for notifying residents. Currently, the
preferred local option appears to be the installation of weather radios in each
residence with an automated gage hookup to the Seattle and Olympia Weather Bu-
reau offices so that information regarding dam failure may be immediately re-
layed. There is discussion of a brochure being printed and mailed to each
resident showing evacuation routes and giving general emergency response infor-
mation as well as Fire District 9 receiving on-going support.

Flood forecasting: Flood forecasting will always be limited in the Skokomish
Valley due to the fact that the river watershed is comparatively small and
doesn't allow for measurable lead time between the rainfall occurrence and
flooding in the valley. The high volumes of rainfall experienced within the
watershed and resulting rapid rise of water levels also limit the time to take
protective actions.

Flood alert: The National Weather Service has a communication system for re-
laying weather watch information to local communities. The information is gen-
eral in terms of amount or duration of storm events. The Mason County Sheriff
Department Dispatch receives the National Weather Service information. Mason
County Emergency Services is then contacted by phone, determines which Fire
Districts or other entities should receive the weather information, and relays
information by phone or radio transmitter. When necessary, the Mason County
Sheriff Department will make direct contact. A 'tone' is transmitted by radio
dispatch to fire district volunteers that a flood watch or alert is in affect.
There are a limited number of receivers available to residents in the Skokomish
Valley (Conversation with Merle McNeil, Mason County Emergency Services
April 3, 1987).

The existing stream gage system consists of stream gages owned and operated by
the Tacoma City Light on the North Fork of the Skokomish River above Lake Cush-
man and on Lake Cushman Dam, Deer Meadow Creek, and on McTaggert Creek above
Gibbons Creek. The United States Geological Service (USGS) maintains the fol-
lowing manual gages:
Purdy Creek - westerly side of State Route 101
Skokomish River - at US 101 bridge, RM 5.3
Skokomish River, North Fork - just above river mile 10
Skokomish River, South Fork - Just above river mile 3

The information from the stream gages is not coordinated with local flood warn-
ing efforts at this time. A volunteer gage reading program could be estab-
lished with a flood preparedness plan which informs residents of specific flood
levels so that they may take pre-planned action. Such actions would be based
on a knowledge of the elevation of their structures and a series of appropriate
preventative measures for each stage of a flood event.

DISASTER PLANS

Flood fightinglevacuationlemergency shelter: Fire District No. 9 is the pri-
mary rescue and evacuation service. The Fire District station is located in
the floodway of the Skokomish River and is floodprone. Access to the station
can be cut off to regular vehicles during a flood event. The district
maintains a 6 x 6 vehicle for evacuating residents in flood events. The com-
munity has an informal network of mutual assistance and a long-term familiarity
with which portions of the Skokomish Valley are more flood prone. On a volun-
teer basis, assistance is-provided to those residents needing to be evacuated.
Currently, there is no flood preparedness plan in place for the fire district
or individuals in the flood prone areas.

There is no system of flood response for minimizing flood damages to property.
An'audit of each structure in the floodplain should be developed which estab-

lishes a list and priority for protective actions. This information should be
kept on file with the fire district, as well as easily accessible to the
residents.

The county sheriff's department provides 24-hour response and serves as a first
point of contact and assistance in relaying for flood warnings. Assistance in
early evacuation is also provided.

Medical Service:

Emergency Shelter:

FLOOD PROOFING
Elevating Structures
Construction Standards for new and reconstructed structures

STRUCTURE RELOCATION
Identify structures within the floodway which should receive priority consider-
ation for relocation. Establish a loan or cost-share program

LAND REGULATION
As discussed in Chapter 6, the primary land use regulation affecting the Skoko-
mish Valley is the state law prohibiting construction of new residences within
a designated floodway. The majority of the Skokomish Valley is within such a
floodway, as recently determined by a flood insurance study for Mason County.

Zoning: Mason County has no zoning in place to regulate siting of development.

Dedication of Land to Open Space:

Local Flood Hazard Ordinance: Mason County does not currently have a flood
hazard ordinance in effect.

DISCLOSURE
Disclosure that property is within a floodprone area becomes even more impor-
tant with the residential development prohibition discussed above.

PUBLIC INFORMATION PROGRAMS
Any effort to reduce flood damages is only as effective as the effort to inform
the public about the extent of potential flood hazard and measures in place to
reduce or prevent the flood-related threats.

FLOOD RECOVERY
(1) Flood insurance maps
(2) Flood emergency operations
Flood fighting

Emergency health care and shelter
(3) Financial assistance for recovery
Low interest loans
Federal reconstruction assistance
Grants and disaster aid
(4) Tax adjustments

FLOOD INSURANCE
Mason County is presently in the emergency phase of the National Flood Insur-
ance Program. The Federal Emergency Management Agency completed a preliminary
flood insurance study in February, 1987 and Mason County is preparing to adopt
the study. A Local Flood Hazard ordinance must also be adopted and adminis-
tered by Mason County to continue eligibility in the National Flood Insurance
Program.

A detailed study was conducted for 6.3 miles of-the Skokomish River, extending
from the State Highway 106 bridge to the confluence of the North Fork Skokomish
River. The area appears to have been selected due to its known severe flood
hazard, as identified at a meeting attended by representatives of the study
contractor, FEMA, and Mason County in May 1980 (FEMA, 1983). Flood elevations
for 10, 50, 100, and 500 year recurrence intervals were calculated. A floodway
was also calculated and mapped which included almost the entire floodplain for
the area studied. Upon adoption of the maps by Mason County, the Skokomish
River floodway will become a 'regulatory floodway,' where development or en-
croachment (filling, etc.) which would cause any increase in the base flood el-
evation must be prohibited (Washington Department of Ecology, 1986).

Approximate studies were conducted for 1.5 miles of the North Fork Skokomish
River, 1.9 miles of the South Fork Skokomish River, and 2.9 miles of Vance
Creek (Appendix A)

FLOOD EMERGENCY OPERATIONS

Pub7ic Works Department: (restoring access)

PUD No. 3: Electrical power restoration and residential safety checks.

FINANCIAL ASSISTANCE FOR RECOVERY
According to Terry Simmonds of the Department of Community Development's Emer-
gency Management Program, over the years Mason County has received Federal Di-
saster Assistance Grants for a number of floods, as shown in Table 7.1. The
Federal Highway Administration-has provided indirect assistance totalling
$170,769.00. To date, no flood hazard mitigation study has been conducted for
Mason County.

Table 7.1. FEDERAL DISASTER ASSISTANCE GRANTS, MASON COUNTY.

-------------------------------------------------------------------------------
Year Type of Disaster Location Amount of Grant
---- ---- -- -------- -------- ------ -- -----
1962 Flooding County $1,218.00

1964 Flooding Hood Canal School
District #404 $1,500.00
Mason County PUD #1 $16,562.00
Mason Cou'nty PUD #3 $13,424.59

----------
Subtotal $31,486.59

1965 Earthquake Mason County School
District #309 $562.00

1974 Flooding County $20,652.15

1975 Flooding County $6,924.00

Total $60,842.74

----------------------------------------------------------------- 7------------
Source: Simmonds, Terry, 1987.

STRUCTURAL MEASURES
(1) Flood diversions
(2) Channel alterations
(3) Dikes, levees, and floodwalls
(4) Dams and reservoirs
(5) Land treatment

STREAMBANK STABILIZATION
Historically, the primary flood control management measures taken in the Skoko-
mish Valley have concentrated on streambank protection measures aimed at reduc-
ing erosion from channel changes.

STORAGE OF FLOOD WATERS
Lake Cushman Dam: The construction of the upper and lower Cushman Dams has ef-
fectively reduced the flow of water from the North Fork of the Skokomish River
which had historically contributed over one-half of the winter stream flow.

Wetlands:

DIKES AND LEVEES
Diversion Dikes and Levees:

Setback Levees and the Floodway:

Mason County Proposal:

INSTREAM WORK
Channel Modification:

Gravel Removal:
(refer to Corps recon. study evaluating feasibility of setback levee)

Mason County Proposal:
(refer to Corps recon. study evaluating feasibility of setback levee)

FLOOD DIVERSION
Bypass Systems:

Existing and Historic Side Channels: Records show that the Skokomish Valley
.floor had an extensive network of side channels which carried flood waters dur-
ing peak flows. These side channels have been filled and blocked off through
the process of converting land for agricultural and residential use.

SUMMARY AND CONCLUSIONS
Both structural and non structural flood control and management measures are
available to Mason County for improving conditions in the Skokomish Valley. To
date, measures taken by local residents and County officials have focused on
structural measures.

Nonstructural measures consist of flood control alternatives which typically
affect one or two structures at a time or limit the location and type of devel-
opment occurring in floodprone areas. Nonstructural measures also include ad-
ministrative or institutional programs such as flood warning and evacuation
systems. Nonstructural approaches can also include administrative procedures
to conserve natural wetlands for flood water storage reservoir use.

Future detailed flood control and management planning for the Skokomish Valley
should include a strong measure of nonstructural alternatives which provide
more cost effective flood protection than certain structural measures. Princi-
pal issues which should be addressed include: and technical assistance to local
residents in self help measures including floodproofing of structures; emer-
gency,warning and evacuation alternatives; land management alternatives and
compliance with state and federal law.

Structural measures typically include construction projects and facilities such
as streambank protection, dikes, gravel and debris removal, bridges and cul-
verts, and flood water storage reservoirs. Past analyses of intensive ap-
proaches to structural solutions have proven not to be cost effective (Chapter
5).

Skokomish Valley has a special problem in that public roads in the Valley are
constructed to finish elevations below annual flood heights (Chapter 3).

The Skokomish Valley has another special problem in that the lower South Fork
and upper main stem are rapidly aggrading (Chapters 3 and 4). The long term
importance of this is that any structural remedies undertaken will have a short
lived value -- probably no more than five years.

It is generally accepted that the incidental flood water storage function of
Cushman Reservoir has helped to reduce the intensity of flooding in the Skoko-
mish Valley by diverting most of the North Fork flows. However, the Cushman
Project was licensed as a single purpose hydroelectric facility.

A major component of future detailed planning for flood control and management
should include a comprehensive and integrated structural program including at
least the following elements: short term bank protection measures to alleviate
existing hazardous conditions; elevating certain low-lying roads such as the
Skokomish Valley Road and Bourgault Road West to maintain the public road sys-
tem in anticipation of future increased flooding; revising the operations of
the Cushman Project to include permanent procedures for flood flow mitigation
and early warning of flood season discharges; a detailed sediment transport
study should be conducted to establish the volume of material within the stream
system, locate the source of material, and determine the feasibility and most
appropriate locations for removing the material from the stream system. Given
that it is difficult-to-impbssible to accurately measure bedload movement, it
will probably be necessary to construct a sediment retention facility without
any knowledge of the volumes of sediment which can be anticipated, and deter-
mine those volumes based on the filling rate of the retention facility.

REFERENCES CITED AND CONSULTED

Abrahamson, Pam. 1986. A detailed listing of the liberations of salmon into
the open waters of the state of Washington during 1985. Progress Report
No. 243. Washington Department of Fisheries, Olympia.

AIA Research Corporation. 1981. Design guidelines for flood damage reduction.
FEMA - 15. Federal Emergency Management Agency, Washington, D. C.

ASFM - see Association.of State Floodplain Managers.

Association of State Floodplain Managers. 1985. Reducing losses in high risk
flood hazard areas: A guidebook for local officials. Federal Emergency
Management Agency Publication FEMA 116 (February 1987).

Ames, James J. and Patrick Bucknell. 1981. Puget Sound river mile index.
Washington Department of Fisheries, Olympia.

Anderson, Jim, et al. 1986. River recreation in Washington: An initial inven-
tory and assessment. National Park Service, Seattle, Washington.

Bell, Milo C. 1982. South Fork Skokomish River hydroelectric project: Techni-
cal Report No. 7, Gravel and sediment transport. School of Fisheries,
University of Washington, Seattle.

Bortleson, G. C., M. J. Chrzastowski, and A. K. Helgerson. 1980. Historical
changes of shoreline and wetland at eleven major deltas in the Puget Sound
region, Washington. Hydrologic Investigations Atlas HA-617. USDI Geo-
logical Survey.

Bortleson, G. C., N. P. Dion, J. B. McConnell, and L. M. Nelson. 1976. Recon-
naissance data on lakes in Washington: Volume 3, Kitsap, Mason, and Pierce
counties. Water Supply Bulletin 43, Volume 3. Washington Department of
Ecology, Olympia.

Bortleson, G. C. and B. L. Foxworthy. 1973. Relative susceptibility of lakes
to water-quality degradation in the southern Hood Canal area, Washington.
Miscellaneous Geological Investigations Map 1-853-8. USDI Geological Sur-
vey.

Burch, G. J., R. K. Bath, I. D. Moore, and E. M. O'Loughlin. 1987. Com-
parative hydrological behavior of forested and cleared catchments in
southeastern Australia. Journal of Hydrology 90: 19-42.

Burroughs, Jr., Edward R. and Byron R. Thomas. 1977. Declining root strength
in Douglas-fir after-fe7ling as a factor in slope stability. Research Pa-
per INT-190. USDA Forest Service Intermountain Forest.and Range Ex-
periment Station.

Ca.lambokidis, J., et al. 1978. Chlorinated hydrocarbon concentrations and the
ecology and behavior of Harbor Seals in Washington state waters. The Ev-
ergreen State College, Olympia, Washington

113

Caldwell', Brad. 1984. Skokomish River - Minimum Stream Flows. Memorandum to
Gordon Zillges, Department of Fisheries, Habitat Management Division.
Canning, Douglas J. 1985. Shoreline b7uff and slope stability: Technical man-
agement options. Shorelands Technical Advisory Paper No. 2. Shorelands &
CZM Program, Washington Department of Ecology.
Canning, Douglas J. and G. Bradford Shea. 1979. Evaluation of the proposed
Northern Tier oil pipeline through Mason County, Washington. (Final re-
port to Mason Regional Planning Council) Northwest Environmental Consult-
ants, Inc. Seattle, Washington.

Carson, R. J., Mackey Smith, and B. L. Foxworthy. 1973. Geologic conditions
related to waste-disposa7 planning in the southern Hood Canal area, Wash
ington. Miscellaneous Geological Investigations Map I-853-D. USDI Geo-
logical Survey.

Castoldi, Pam. 1983. A detailed listing of the liberations of salmon into the
open waters of the state of Washington during 1982. Progress Report No.
185. Washington Department of Fisheries, Olympia.

CH2M Hill, Inc. 1983. South Fork Skokomish Hydroelectric Project: Draft en-
vironmental impact statement. Public Utilities District #3 of Mason
County, Shelton, Washington.

Cowley, Earl W. 1958. Report of field examination Skokomish River watershed,
Mason County, Washington. US Soil Conservation Service, Spokane, Washing
ton.

Cummans, J. E. 1974. Flood profiles and inundated areas along the Skokomish
River, Washington. Water Resources Investigations No. 62-73. USDI Geo-
logical Survey, Tacoma, Washington.
I
Division of Marine Land Management. 1977. Washington marine atlas, Volume 2:
South inland waters. Washington Department of Natural Resources, Olympia.

-Drainage and Land Stabilization Technical Committee. 1970. Comprehensive
study of water and related land resources, Puget Sound and adjacent wa-
ters: Appendix XIV, Watershed management. Pacific Northwest River Basins
Commission.

Duncan, S. H., R. E. Bilby, J. W. Ward, and J. T. Heffner. 1987. Transport of
road-surface sediment through ephemeral stream channels. Water Resources
Bulletin 23(l):113-119.

Dunn, B. C. 1942. Report and survey of Skokomish River, Mason County, Wash-
ington. (Presented to the House of Representatives, 76th Congress, 1st
Session, March 23, 1942.) Board of Engineers for Rivers and Harbors, US
Army Corps of Engineers, Washington D.C.

Fajen, Otto and James L. Robinson. 1985. Stream corridor management: A pro-
posed response to streambank erosion. USDA Soil Conservation Service and
Missouri Department of Conservation.

114

Federal Emergency Management Agency. 1987. Flood insurance study: Mason
County, Washington unincorporated areas. (Community number 530115) Fed-
eral Emergency Management Agency.

FEMA - see Federal Emergency Management Agency.

Fiksdal, Alan J. and Matthew J. Brunengo. 1981. Forest slope stability
project, Phase II, Volume 1. WDOE 81-14. Washington Department of Ecol-
ogy, Olympia.

Findlay, John D. 1973. Map showing spawning areas of anadromous fish in
southern Hood Canal, Washington. Miscellaneous Geological Investigations
Map I-853-A. USDI Geological Survey.

Fish and Wildlife Technical Committee. 1970. Comprehensive study of water and
related land resources, Puget Sound and adjacent waters, Appendix XI: Fish
and wildlife. Pacific Northwest River Basi-ns Commission.

Fleskes, Carol and Marty O'Connor. 1980. Skokomish-Dosewa77ips Basin WRIA 16:
Office Report No. 74. Water Resources Management Division, Washington De-
partment of Ecology, Olympia.

Flood Control Technical Committee. 1970. Comprehensive study of water and re-
lated land resources, Puget Sound and adjacent waters: Appendix XII, Flood
control. Pacific Northwest River Basins Commission.

Floodplain Management Section. 1986. F7oodp7ain management handbook for local
administrators. Shorelands and Coastal Zone Management Program, Washing-
ton Department of Ecology, Olympia.

Franklin, Jerry F. and C. T. Dyrness. 1973. Natural vegetation of Oregon and
Washington. General Technical Report PNW-8. USDA Forest Service.

Geppert, Rollin R., Charles W. Lorenz, and Arthur G. Larson. 1984. Cumulative
effects of forest practices on the environment: A state of the knowledge.
Washington Forest Practices Board, Olympia.

Harr, R. Dennis. 1982. Prefiled testimony prepared for US Forest Service Gen-
eral Counsel, Portland, Oregon, for potential litigation in Skokomish In-
dian Tribe v Forest Supervisor, Olympic National Forest.

Harris, D. D. 1973. Hydrologic changes after clear-cut logging in a small Or-
egon coastal watershed. Jour. Research U. S. Geo7. Survey 1(4): 487-491.

Hill, Pamela M. 1983. A detailed listing of the liberations of salmon into
the open waters of the state of Washington during 1983. Progress Report
No. 210. Washington Department of Fisheries, Olympia.

Hogan, Dwain F. 1987. Letter to Edward Binder, Skokomish Indian Tribe, dated
12 March 1987. US Army Corps of Engineers, Seattle, Washington

Hood Canal Coordinating Council. 1986. Hood Canal Regional Planning Policy.
Hood Canal Coordinating Council, Silverdale, Washington.

115

Huntting, Marshall T. 1956. Inventory of Washington minerals: Part 2, Metal-
7ic minerals. Bulletin 37. Division of Mines and Geology, Washington De-
partment of Conservation and Development, Olympia.

Hutchison, R. P. 1973. Public recreation resources and facilities in the
southern Hood Canal area, Washington. Niscel7aneous Geological Investiga-
tions Nap I-853-G. USDI Geological Survey.

James, Karen. 1980. The Skokomish River North Fork: An ethnographic and his-
torica7 study. Skokomish Consulting Services, Skokomish Indian Tribe,
Shelton, Washington

James, Karen and Victor Martino. 1980. Water resources of the Skokomish In-
dian Tribe. Skokomish Consulting Services, Skokomish Indian Tribe,
Shelton, Washington

Johnson, William K. 1978. Physica7 and economic feasibility of nonstructural
flood plain management measures. US Army Corps of Engineers

Kehoe, David M. 1982. Sources of sediment to Grays Harbor Estuary. US Army
Corps of Engineers, Seattle District.

Kendra, Will. 1985. North Fork Skokomish River streamf7ow and water qua7ity
survey. Washington State Department of Ecology Memorandum from Will
Kendra to Greg Sorlie, dated July 24, 1985.

Keown, Malcolm P. 1983. Streambank protection guidelines for landowners and
local governments. Waterways Experiment Station, US Army Corps of Engi-
neers, Vicksburg, Mississippi.

Kirby, Loree L. 1985. A detailed listing of the liberations of salmon into
the open waters of the state of Washington during 1984. Progress Report
No. 231. Washington Department of Fisheries, Olympia.

Klingeman, Peter C., Scott M. Kehe, and Yaw A. Owusu. 1984. Streambank ero-
sion protection and channel scour manipulation using rockfi77 dikes and
gabions. WRRI-98. Water Resources Research Institute, Oregon State Uni-
versity, Corvallis.

Land Usage and Development Technical Committee. 1970. Comprehensive study of
water and re7ated*7and resources, Puget Sound and adjacent waters: Appen-
dix V, Water-re7ated land resources. Pacific Northwest River Basins Com-
mission.

Latourell Associates, The. 1974. Comprehensive Plan: Skokomish Indian Reser-
vation. Skokomish Indian Tribe, Shelton, Washington.

Martinson, R. K. 1973. Sa7t-water fishery resources and shoreline development
in the southern Hood Canal area, Washington. Miscellaneous Geological In-
vestigations Map I-853-E. USDI Geological Survey.

Mason Regional Planning Council. 1982. Mason County Comprehensive Plan. Ma-
son Regional Planning Council, Shelton, Washington.

116

McFarland, Carl R. 1983. Oil and gas exploration in Washington, 1900 .1982.
Information Circular 75. Division of Geology and Earth Resources, Wash-
ington Department of Natural Resources, Olympia. (Including addendum
dated 29 January 1986.)

Megahan, W. F. and W. J. Kidd. 1972. Effects of logging roads on sediment
production rates in the Idaho batho7ith. Research Paper INT-123. USDA
Forest Service.

Milhous, R. T. 1982. Effect of sediment transport and flow regulation on the
ecology of gravel-bed rivers. pp 819-842 in: R. D. Hey, J. C. Bathhurst,
and C. R. Thorne. Gravel-bed rivers. J. Wiley, New York.

Molenaar, Dee and J. E. Cummans. 1973. Water resources of the Skokomish In-
dian Reservation, Washington. US Geological Survey, Tacoma, Washington.

Molenaar, Dee and John B. Noble. 1970. Geology and related ground-water oc-
currence, southeastern Mason County, Washington. Water Supply Bulletin
No. 29. Washington Department of Water Resources, Olympia.

Morrison-Maierle, Inc. 1979. Skokomish River hydropower and natural flow
evaluation. (Final.report to Skokomish Consulting-Services, Shelton Wash-
ington.) Morrison-Maierle Inc., Helena, Montana.

Navigation Technical Committee. 1970. Comprehensive study of water and re-
7ated land resources, Puget Sound and adjacent waters: Appendix VII,
Navigation. Pacific Northwest River Basins Commission.

Ness, A. 0. and R. H. Fowler. 1960. Soil survey of Mason County, Washington.
USDA Soil Conservation Service.

Newkirk, Ray. 1983. Skokomish-Dosewal7ips Basin WRIA 16, Technical Document
Supplement (Natural Flow Study). Office Report No. 74-A. Water Resources
Management Division, Washington Department of Ecology.

Office of Financial Management. 1986. 1986 Population Trends for Washington
State. Office of Financial Management, Olympia, Washington-

OFM - see Office of Financial Management.

Olson, Forrest W. 1983. Flow-related effects of the proposed South Fork Sko-
komish River hydroelectric project on salmon and Steelhead. CH2M Hill,
Inc., Bellevue, Washington.

Olympic National Forest. 1978. Canal land management plan: Final environmen-
ta7 impact statement. Olympic National Forest, Olympia, Washington.

Olympic National Forest. 1986a. Proposed land and resource management p7an:
Draft plan. Olympic National Forest, Olympia, Washington.

Olympic National Forest. 1986b. Proposed land and resource management plan:
Draft environmental impact statement. Olympic National Forest, Olympia,
Washington.

117

ONF - see Olympic National Forest.

Phillips, Earl L. 1968. Washington climate for these counties: King, Kitsap,
Mason, and Pierce. Publication E.M. 2734. Cooperative Extension Service,
College of Agriculture, Washington State University, Pullman.

Phillips, Earl L. and Wallace R. Donaldson. 1972. Washington climate for
these counties: Cla77am, Grays Harbor, Jefferson, Pacific, and Wahkiakum.
Publication EM 3708. Cooperative Extension Service, College of Agricul-
ture, Washington State University, Pullman.

Proctor, C. M, et al. 1980. An ecological characterization of the Pacific
Northwest coastal region. 5 Vol. FWSIOBS-79111 - 79115. US Fish and
Wildlife Service, Biological Services Program.

Recreational Technical Committee. 1970. Comprehensive study of water and re-
7ated land resources, Puget Sound and adjacent waters: Appendix X, Recre-
ation. Pacific Northwest River Basins Commission.

Richardson, Donald. 1973. Streamf7ow in the southern Hood Canal area,
Washington, as related to land-use planning. Miscellaneous Geological In-
vestigations Map I-853-C. USDI Geological Survey.
Rushton, Clifford D. 1985. Instre@m Resources Protection Program: Skokomish
Dosewa77ips Water Resource Inventory Area. Washington Department of Ecol-
ogy, Olympia.

Saunders, Robert S. 1981. Land Use Ordinance: Skokomish Indian Tribe. South
Puget Intertribal Planning Agency.
SCS - see Skokomish Consulting Services.

SPIPA - see South Puget Intertribal Planning Agency.

Sedell, James R. and Wayne S. Duval. 1985. Influence of forest and rangeland
management on anadromous fish habitat in western North America. General
Technical Report PNW-186. USDA Forest Service Pacific Northwest Forest
and Range Experiment Station, Portland, Oregon.

Sedell, James R., Fred H. Everest, and Frederick J. Swanson. 1982. Fish
habitat and streamside management: Past and present. pp 244-255 in: Pro-
ceedings of the Society of American Foresters, Annual Meeting (September
27-30, 1981). Society of American Foresters, Bethesda, Maryland.

Sedell, James R. and Judith L. Froggatt. 1984. Importance of streamside for-
ests to large rivers: The isolation of the Willamette River, Oregon,
U.S.A., from its floodplain by snagging and'streamside forest removal.
Verh. Internat. Verein. Limno7. 22:1828-1834.

Sedell, James R. and Karen J. Luchessa. 1982. Using the historical record as
an aid to salmonid habitat enhancement. pp 210-223 in: Neil B. Arman-
trout, Ed. Proceedings of a Symposium on Acquisition and Utilization of
Aquatic Habitat Inventory Information, 28-30 October 1981, Portland, Or-
egon. Western Division, American Fisheries Society, Bethesda, Maryland.

118

Smith, Mackey, and R. J. Carson. 1973. Relative slope stability of the south-
ern Hood Canal area, Washington. Miscellaneous Geological Investigations
Map I-853-F. USDI Geological Survey.

Sorlie, Greg. 1975. Background information for water resources management
planning in the western and southern Puget Sound basins. WRIS Technical
Bulletin No. 18. Washington Department of Ecology, Olympia.

South Puget Intertribal Planning Agency & Skokomish Consulting Services. 1979.
Overall Economic Development Plan: Skokomish Indian Tribe. Skokomish In-
dian Tribe, Shelton, Washington.

Strickland, Richard (ed.). 1986. Wetland functions, rehabilitation, and cre-
ation in the Pacific Northwest: The state of our understanding. Proceed-
ings of a conference held April 30 - May 2, 1986, Fort Worden State Park,
Port Townsend, Washington. Washington Department of Ecology publication
number 86-14.

Swanston, Douglas N. 1978. Effect of geology on soil mass movement activity
in the Pacific Northwest. pp 89-115 in: Forest Soils and Land Use: Proc.
Fifth North Amer. For. Soils Conf., Colo. State Univ. Aug. 1978. USDA
Forest Service.

Tacoma City Light. 1985. Tacoma power system information. City of Tacoma,
Department of Public Utilities, Light Division.

TCL - see Tacoma City Light.

Troendle, C. A. and R. M. King. 1987. The effect of partial and clearcutting
on streamflow at Deadhorse Creek, Colorado. Journal of Hydrology 90:
145-157.

Valentine, Grant M. and Marshall T. Huntting. 1960. Inventory of Washington
minerals: Part 1, Nonmetallic minerals. Bulletin 37. Division of Mines
and Geology, Washington Department of Conservation, Olympia.

Wampler, Phillip L. 1980. Instream flow requirements of the lower North Fork,
South Fork and mainstem Skokomish River. Fisheries Assistance Office, US
Fish and Wildlife Service, Olympia, Washington.

Washington Department of Fisheries. 1957. Research re7ating to fisheries
problems that will arise in conjunction with current and projected hydro-
electric developments in the Skokomish River. Washington Department of
Fisheries, Olympia.

Washington Department of Fisheries. 1987. Watershed planning: Proposed en-
hancement report. Washington Department of Fisheries, Olympia.

WDOF - see Washington Department of Fisheries.

Whitlam, Robert G. 1987. State Archaeologist, Washington Office of Archaeol-
ogy and Historical Preservation, Olympia. Letter to Douglas J. Canning,
Washington Department of Ecology.

119

Williams, R. Walter, Richard M. Laramie, and James J. Ames. 1975. A catalog
of Washington streams and salmon utilization: Volume 1, Puget Sound re-
gion. Washington Department of Fisheries, Olympia.

Williams, J. R., H. E. Pearson, and J. D. Wilson. 1985. Streamflow statistics
and drainage-basin characteristics for the Puget Sound region, Washington:
Volume 1, Western and southern Puget Sound. Open File Report 84-144-A. US
Geological Survey, Tacoma, Washington.

Woolridge, David D. 1971. Revised objectives for design of urban stormwater
systems in the Puget Sound region. Completion report for US Department of
the Interior OWRR Project 8-035-WASH, Annual Allotment Agreement Number
14-31-0001-3140. College of Forest Resources, University of Washington,
Seattle.

Yoshinaka, M. S., and N. J. Ellifret. 1974. Hood Canal: Priorities for tomor-
row. US Fish and Wildlife Service, Portland, Oregon.

120

SKOKOMISH RIVER
COMPREHENSIVE FLOOD CONTROL MANAGEMENT PLAN

APPENDIX A
SKOKOMISH RIVER INVESTIGATION

June 1987

Dr. Donald R. Reichmuth

Geomax, P.C.
Professional Engineers and Surveyors
622 South 6th Avenue
Bozeman, Montana 59715

A-1

INTRODUCTION
In April 1987, the Floodplain Management Section, Shorelands and Coastal Zone
Management Section, Washington Department of Ecology contracted with Dr. Donald
R. Reichmuth, a specialist in river and streambank erosion control and manage-
ment. Dr. Reichmuth conducted an aerial reconnaissance of the Skokomish Valley
and central South Fork basin on May 20th, as well as inspections of the two
streambank erosion hazard areas -- the vicinity of Skokomish Valley Community
Church, and the vicinity of River Mile (RM) 1.8 on the South Fork.

Dr. Reichmuth's report to Ecology is reproduced in its entirety in this appen-
dix.

A-3

GEOMAX

PROFESSIONAL ENGINEERS & SURVEYORS

June 25, 1987 622 SOUTH SIXTH AVENUE BOZEMAN, MONTANA 59715
TELEPHONE: (406) 586-0730

TO. Lisa Randlettte, Washington Capt. of Ecology

FROM: Dr. Donald R. Reichmuth

RE: Skokomish River investigation

This report is based on my examination of photos and reports

provided by the Department of Ecology, a one-day Field investi-

gation which included both an aerial observation of most of the

drainage and a ground investigation of some of the lower river.

Additionally, discussions were held with local landowners, county

officials and personnel from the affected State agencies. These

field investigations were carried out on May 20, 1987.

The Skokomish River system consists of two primary tribu-

taries, each approximately thirty miles long, and a lower, main

stem which is approximately tan miles long that has its mouth in

he Hood Canal. The lower portions of the river are affected by

tide, and, consequently, have a vary Flat gradient. On the other

hand, the upper drainages have many very steep side tributaries

which feed into the main Forks. The north fork is totally con-

trolled by Lake Cushman, and most of the water is diverted out of

the reservoir directly into Hood Canal for power generation.

This loss of water in the north Fork does limit the sediment

carrying capacity of the main stem because of loss of water.

With Lake Cushman totally trapping sediment from the upper

drainage, the north fork contributes very little material to the

main stem.

Page Two Skokomish River Report June 13, 1987

The upper south Fork is characterized bg moderate gratJLent,

and extremely steep side drainages entering the stream. The

lower five miles of the south Fork are largely on bedrock, and

here the stream has been incised and Flows in a rather steep,

narrow gorge. Below the gorge, the south Fork has a quite Flat

gradient, and the areas here and below the junction of the north

Fork on the main stem are flowing in a rather wide valley with

fairly low gradients.

It is apparent that this lower area, from about five miles

upstream From the mouth to the area where the south fork enters

the gorge, is receiving large quantities of sediment, which is

destabilizing the streams. It was observed in this area that

large gravel bars are building, and, consequently, the stream is

Forced to erode into banks where Finer or more erodible material

is present. This has produced considerable bank erosion, and has

-he channel capacity sufficiently so that floods are
diminished 4L.

occurring into areas and at frequencies that have not been

experienced earlier.

The aerial observation of the upper south fork drainage

revealed that large quantities of sediment are being released

From the heavily logged areas that cover large portions of the

basin. Examples oil this logging and erosion are typified by

photos A and B which accompany this report. These photos are

typical of the logging activity in most of the upper south

fork.

Page Three Skokomish River Report June 19, 1987

Photo A illustrates the general characteristic OF most of

the upper basin. As seen in this photograph, there are numerous

clear cuts of varying age, and many log haul roads cutting the

hillsides. The river channel is braided and unstable, and large

quantities of gravel and logging debris or trees are seen in 1--he

floodplain.

Photo B shows a more detailed picture of one side drainage.

The gravel moving down this drainage is clearly seen in the

photograph. The tree buffer which separates the logging area

from the river bottom has not been able to Filter out and trap

the.gravel from the upper areas. Many of the logs seen on the

floodplain undoubtedly are derived from the stream being forced

into the wooded banks by the gravel depositions occurring in the

main channel. These gravels are Flushed down the stream and

passed through the-steeper gorge areas without causing

significan'L-- deposition or bank erosion, because this'section is

confined by bedrock. However, once the river leaves this gorge,

large quantities of gravel are immediately deposited. This is

shown very clearly in the left side of Photo C. Here it is noted

that gravel has been deposited Far away from the channel and that

the bare depositional area is very large, as compared with the

gorge areas seen on the right side of the photograph.

From this point downstream to near the Indian reservation

border, which i s some five miles upstream from the mouth, the

Page Four Skokomish River Report June 19, 1987

river is characterized by a braided, unstable set of channels,

and numerous unvegetated gravel bars. These bars are clearly

filling the =hannel, which greatly reduces the flood carrying

capacity of the river. Consequently, much of the water in flood

stage wiII go out into the Farm areas. Photo 0 is typical of the

conditions which occur in this zone. Because the gradient is so

Flat, only the Finer materials can be carried down to the mouth

near the Hood Canal. In these areas, one sees only deposition of

A..Lner materials.

Because the upper drainages are contributing so much

material and show no signs of reaching stability, it is expected

that this downstream migration of large quantities of gravel will

continue until something is done to control the matprial nearer

its source. This will require either limiting future logging, or

carefully controlling the areas where logging occurs, so that

sediment releases are minimized. Additionally, control

structures should be placed in the upper drainage to trap as much

gravel as possible, before it reaches the canyon area. If these

measures are not taken, it is virtually impossible to protect the

loWer agricultural areas from extreme bank instability, because

the gravels will, of necessity, deposit within the farm area,

causing the stream to be diverted into the banks or fields during

Flood stage. Until the upper area is controlled, there is really

very little that can be done to protect the lower agricultural

areas from bank erosion and flooding.

Page Five Skokomi5h River Report June 19, 1987

It is possible to locally protect structures such as

highways, and perhaps some of the keg building areas, bg

J. -ructures in the lower area. At best, these will be
installing st &_

temporarg measures, which do not address the prime cause but onlg

deal with the localized effects of the gravel depositions.

It should be clear from the above discussion that a solution

to the erosion and increased flooding problems occurring in the

lower agricultural area requires more than a localized "band-aid"

approach to the problem. It is therefore recommended that an

integrated, drainage-wide program be established, which simul-

taneouslg considers the upper drainage affected by logging with

the middle agricultural area and the lower tidal area. IF such a
program is not established, it is my feeling that there'will be

continuous conflict bet-wean the logging and agricultural

interests in the lower areas. It is equally clear that if work

is onlg attempted in the agricultural area, the money will be

largely wasted, because these efforts are only dealing with

symptoms and not the root cause of the instability which has been

observed on the river.

GEOMAX, P.C.

By....- .. . ........... .
Dr .Donald R. Reichmuth, PE/LS
,1. @_ J__
President

DRR:mdl
Enclosures

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SKOKOMISH RIVER
I COMPREHENSIVE FLOOD CONTROL MANAGEMENT PLAN

APPENDIX B
I HISTORIC FLOOD CONTROL WORK
I
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I
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I

I
I -
I
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B-1
I . I

INTRODUCTION
This appendix summarizes known flood control work and other works affecting
flooding and stream flow undertaken in the Skokomish Valley during the past
forty years. The information assembled in this appendix is not exhaustive; it
is based on available information on state cost sharing projects, flood control
work permits, and Hydraulic Project Approval (HPA) records. Numerous flood
control works have been constructed without benefit of either a state cost
sharing or a permit.

Flood control works constructed under state cost sharing programs are summa-
rized in Table B1.

Flood control works permitted under the Flood Control Zone Permit system are
summarized in Table B3.

Instream and streambank work permitted under the Hydraulic Project Approval
program is summarized in Table B4.

B-3

Table B1. FLOOD CONTROL COST SHARE WORK, SKOKOMISH RIVER VALLEY, 1950 - 1973.

-------------------------------------------------------------------------------
Stream Work Nature Project Cost, $
Section(s); Township, Range Period of Work Total State Share

-------------------------------------------------------------------------------
Skokomish 8-9, 1949 CA 1,650 825
7,8,9,16,17,18; 21N, 4W

Vance Creek 6-9, 1950 CA, RA, 12,551 6,275
12,13; 21N, 4W SG

Skokomish 8-9, 1951 CB 700 280
W12; 21N, 4W

Skokomish 7-9, 1951 CA 1,075 430
W12; 21N, 4W

Skokomish 1-3, 1953 CB 566 226
NW18; 21N, 4W

Skokomish 9-10, 1953 CB 8,080 3,232
7,8,9,18; 21N, 4W
12,13; 21N, 5W

Skokomish 9, 1953 CB 3,000 1,200
7; 21N, 4W

Skokomish 8-9, 1953 CC, DB, 12,736 5,094
7,8,9,16,17,18; 21N, 4W DC1
Vance Creek
11,12,13; 21N, 4W

Skokomish & Vance Creek 12, 1954 CA 1,456 582
12,13; 21N, 4W

Skokomish 6, 1973 RA 3,570 860

TOTAL 45,384 19,004
-------------------------------------------------------------------------------
Notes:
1. All projects completed as State Flood Control Participation work under Chap-
ter 86.26 RCW with Mason County as the participating agency.
2. See Table B2 for a key to the Nature of Work codes.

B-4

Table B2. NATURE OF WORK CODES (Table BI).
-------------------------------------------------------------------------------
Code Nature of Work

---- ------ -- ----
C Channel Modification
CA -------- Bar-Removal-or-Dredging ----------------------------------------------
CB Debris Removal, Jam Removal
cc Change or Realignment
CD Stabilization

D Dike

DA Restored
DB Repaired
DC Improved
DC1 New
Dcla Widened
DCIb Heightened
DC1c Lengthened
DC2 Relocated
DE Reinforced

GM General Maintenance

-------------------------------------------------------------------------------
OD Outlet Ditch
DRD Drainage Ditch
BM Borrow Material

R Revetment (Riprap)
-------------------------------------------------------------------------------
RA Rock
RAa Reinforcing
RB Brush
RC Tied Trees
RD Piling or Timber Cribbing

SD Drainage Structures

-------------------------------------------------------------------------------
SDA Culvert
SDB Tide Gate
SG Groin

-------------------------------------------------------------------------------

B-5

Table B3. FLOOD CONTROL PERMITS, SKOKOMISH FLOOD CONTROL ZONE 16. Page 1.

-------------------------------------------------------------------------------
Permit Stream Applicant Description of Work
Year Section(s); Township, Range
-------------------------------------------------------------------------------
101 Hunter Creek Mason County Hunter Creek Bridge.
1956 16; 21N; 4W

102 Skokomish River Mason County Revetment; construction
1962 of Purdy Cutoff Road.

103 Skokomish River Mason County Restoration & revetment
1962 on road near & along
Vance Creek.

105 South Fork Herbert Baze Rock riprap revetment
1964 S1/2, SE1/4, 12; 21N; 5W

106 Hunter Creek Arvid Johnson Channel modification;
1965 W1/2, 17; E1/2, 18; 21N; 4W debris removal.

107 Hunter Creek Haldane Channel modificati,on;
1965 N1/2, 17; 21N; 4W Johnson debris removal.

108 South Fork Theodore Debris removal;
1965 12; 21N; 5W Richert gravel bar removal.

110 Skokomish River Hunter Cabled log revetment.
1965 SEI/4, 8; 21N; 4W Brothers

III Skokomish River Martin Smith Revetment.
1965 SW1/4, 9; 21N; 4W

112 North Fork Ted Richert Diking; riprap.
1966 7; 21N; 4W

113 South Fork C. D. Gravett Cabled tree revetment.
1966 12; 21N; 5W

114 not identified Hunter Dike; cabled tree
1966 SE1/4, 12; 21N; 4W Brothers revetment.

115 Skokomish River Hunter Dike.
1966 NWI/4, 13; 21N; 4W Brothers

116 Vance Creek C. L. Barnett Revetment; channel
1967 SW1/4, 11; 21N; 5W realignment.

117 Vance Creek Charles Linder Riprap; wing dike.
1967 SE1/4, 12; 21N; 5W

118 Vance Creek Hayes Davis Dike reconstruction.
1967 SE1/4, 12; 21N; 5W

-------------------------------------------------------------------------------

B-6

Table B3. FLOOD CONTROL PERMITS, SKOKOMISH FLOOD CONTROL ZONE 16. Page 2.

-------------------------------------------------------------------------------
Permit Stream Applicant Description of Work
Year Section(s); Township, Range
-------------------------------------------------------------------------------
119 Hunter Creek Wash. Dept. Construct fish rearing
1968 SWI/4, NE1/4, 18; 21N; 4W Game ponds.

320 Vance Creek Wash. Dept. Bridge and culvert
1969 NE1/4, SW1/4, 15; 21N; 4W Highways placement.

564 Skokomish River Ted Richert Dike reconstruction.
1970 E1/2, 12; 21N; 5W

854 Skokomish,River Emil Griebel Construct cabin.
1971 NE1/4, 16; 21N; 4W

945 Skokomish River Mason County Rock riprap.
1971 NWI/4, 17; 21N; 4W

1267 Skokomish River Hunter Extend existing dike.
1971 NW1/4, 13; 21N; 4W Brothers

1323 Skokomish River Wash. Dept. Construct public fishing
1973 S1/2, 9; 21N; 4W Game access.

1471 not identified Wash. Dept. Riprap revetment.
1975 NWI/4, NW1/4, 7; 21N; 4W Highways

1478 Hunter Creek Wash. Dept. Construct earthfill
1976 SEI/4, NW1/4, 18, 21N; 4W Game steelhead rearing pond.

1487 not identifi ed Ted Richert Debris removal.
1976 NE1/4, NE1/4, 18; 21N; 4W

1529 Skokomish River Glenn Riprap.
1976 N1/2, 16; 21N; 4W Breedlove

1624 Purdy Creek Wash. Dept. Construct drainage
1977 SW1/4, SW1/4, 15; 21N; 4W Fisheries ditch, rearing pond,
and road.

1635 unnamed Purdy Ck. tributary Clinton Taylor Construct residence.
1977 SEI/4, SE1/4, 16; 21N; 4W

1747 Weaver Creek Wash. Dept. Construct salmon rearing
1978 E1/2, 16; 21N; 4W Fisheries facilities.

1773 Skokomish River Wash. Dept. Structural fill.
1979 SW1/4, 15; 21N; 4W Ftsheries .

1799 South Fork: 12; 21N; 5W Skok. Flood Debris removal.
1979 18; 21N; 4W Control Dist.

-------------------------------------------------------------------------------

B-7

Table B3. FL OOD CONTROL PERMITS, SKOKOMISH FLOOD CONTROL ZONE 16. Page 3.
-------------------------------------------------------------------------------
Permit Stream Applicant Description of Work
Year Section(s); Township, Range
-------------------------------------------------------------------------------
2032 South Fork Vince McNally Log revetment.
1981 NW1/4, 12; 21N; 5W

2124 Skokomish River Wash. Dept. Structural fill
1982 E1/2, 15; 21N; 4W Fisheries maintenance.

2181 unnamed side channel Wash. Dept. Replace bridge.
1983 N1/2, 15; 21N; 4W Transportation

2187 Purdy Creek Wash. Dept. Construct salmon
1984 SW1/4, 15; 21N; 4W Fisherie s incubation ponds
and wells.

2286 Purdy Creek Wash. Dept. Repair bridge.
1986 SW1/4, 15; 21N; 4W Transportation
-------------------------------------------------------------------------------
Source: Washington Department of Ecology files.

B-8

Table B4. FLOOD CONTROL RELATED HYDRAULIC PROJECT APPROVAL (HPA) PERMITS,
SKOKOMISH RIVER VALLEY. Page I

--------- ----- ------- ---- -
Stream Applicant Description of Work
Year Section(s); Township, Range
1981 ------ Skokomish-River --------------- W.-Bourgault --- Debris-removal;-bank ----
15; 21N; 4W. protection.

1981 Vance Creek W. Bresee Debris removal.
12; 21N; 5W.

1981 Vance Creek P. Carney Bank protection.
12; 21N; 5W.

1981 Skokomish River James Cox Bank protection.
12; 21N; 5W.

1981 Skokomish River Mason County Bank protection.
17; 21N; 4W.

1981 Weaver Creek Mason Debris removal.
15; 21N; 4W. Construction

1981' South Fork Skokomish Y. McNally Debris removal.
12; 21N; 5W.

1981 Skokomish River Skok. Flood Bank protection.
15; 21N; 4W. Cont. Dist.

1982 Weaver Creek W. Bourgault Debris removal.
15; 21N; 4W.

1982 Vance Creek P. Carney Bank protection.
11; 21N; 5W.

1982 North Fork Wash. Dept. Debris removal.
7; 21N; 4W. Fisheries

1982 Hunter Creek H. Johnson Debris removal.
17; 21N; 4W.

1983 Purdy Creek Wash. Dept. Debris removal.
14; 21N; 4W. Fisheries

1983 Weaver Creek Wash. Dept. Debris removal.
14; 21N; 4W. Fisheries

1983 Skokomish River H. Johnson Gravel removal.
17; 21N; 4W.

1983 Hunter Creek W. Johnson Debris removal.
18; 21N; 4W.

-------------------------------------------------------------------------------

B-9

Table B4. FLOOD CONTROL RELATED HYDRAULIC PROJECT APPROVAL (HPA) PERMITS,
SKOKOMISH RIVER VALLEY. Page 2

------ --------- ----------- -- ----
Stream Applicant Description of Work
Year Section(s); Township, Range

-------------------------------------------------------------------------------
1983 Weaver Creek Mason County Bridge/culvert
15; 21N; 4W Public Works removal.

1983 South Fork Skokomish Ted Richert Bank protection.
12; 21N; 5W.

1983 Skokomish River Ted Richert Bank protection.
7; 21N; 4W.

1983 Weaver Creek Tozier Bros. Bridge construction.
15; 21N; 4W.

1984 Skokomish River Wash. Dept. Bridge replacement.
15; 21N; 4W Transportation

1984 Weaver Creek Wash. Dept. Debris removal.
16; 21N; 4W Fisheries

1984 Purdy Creek Wash. Dept. Debris removal.
14; 21N; 4W. Fisheries

1984 Weaver Creek Mason County Bridge/culvert
15; 21N; 4W Pablic Works removal.

1984 Weaver Creek Tozier Bros. Bridge construction.
18; 21N; 4W.

1985 Vance Creek Mason County Bridge maintenance.
11; 21N; 5W.

1985-86 Hunter Creek Wash. Dept. Bank protection.
18; 31N; 4W. Game

1985-88 Purdy & Weaver creeks Wash. Dept. Debris removal.
14; 21N; 4W.

1986 Skokomish River Wash. Dept. Bridge/culvert
12; 21N; 4W Transport ation removal

1986 Swift Creek Mason County Shoreline
18; 21N; 4W Public Works maintenance.

1986-87 Vance Creek Mason County Bridge'construction.
11; 21N; 5W. Public Works

1987 Purdy Creek Wash. Dept. Bridge construction.
15;-21N; 4W.
---------------------------------------------------------------------------

B-10 I

J; I

Chapter 8

RECOMMENDED FLOOD CONTROL MANAGEMENT PLAN

INTRODUCTION
This study has addressed the problems associated with flooding on the Skokomish
River and its tributaries. The study has also discussed some flood control
measures used in other communities for reducing flood damages. This chapter
recommends alternatives to be further refined and implemented by Mason County
in a comprehensive flood control management plan. A management strategy which
accounts for all affected land use interests must be developed, from assisting
individuals with floodproofing their homes, to making the public roads safer
during flood events, to addressing the long term problems of an aggrading and
severely floodprone area.

Some difficult questions must be asked within Mason County, and answered.
How much in the way of financial and technical resources can Mason County af-
ford to commit to maintaining the Skokomish River in its present channel and
what can be done if there is not adequate funding available?

What can Mason County do to maintain the channel capacity of the Skokomish
River or risk the increasing frequency and severity of flooding in the Skoko-
mish Valley?

What responsibility does Mason County have in alleviating the potential flood
threat and at what point will Mason County have to decide that it cannot guar-
antee the residents of the Skokomish Valley a safe home and a continued agri-
cultural livelihood?

What is the worst case scenario for flooding in the Skokomish Valley and how
will Mason County avoid it?

Local residents and Mason County must choose from immediate and short-term al-
ternatives to address current flood damage problems. The alternatives pre-
sented i,n this chapter as recommendations address:
1. Continuing existing practices
2. Developing and implementing emergency preparedness plans
3. Floodproofing structures
4. Providing for storage of floodwaters
5. Watershed management to limit excessive sedimentation or flooding
6. Artificial or supplemental channel maintenance
7. Diking floodprone areas
8. Bank stabilization
9. Constructing instream diversions in critical areas

The alternatives described and evaluated are not necessarily mutually exclu-
sive. Some alternatives, or aspects of alternatives could be combined. The
purpose of describing these alternatives is to outline the array of options
available.

Long-term recommendations are also made for the study of aggradation and gravel
@$ W

source. Failure to implement the long-term recommendation will compromise the
long term effectiveness of immediate and short term measures.

FLOOD CONTROL MANAGEMENT ALTERNATIVES

ALTERNATIVE 1: CONTINUE EXISTING PRACTICES
Description: No major additional actions would be taken to reduce flood dam-
ages in the Skokomish Valley through nonstructural or structural measures. No
new residential structures would be constructed within the regulatory floodway,
as a requirement of Chapter 86.16 RCW Flood Control Zone Act. Development
within the 100-year floodplain would continue to be unregulated since there is
no zoning in effect. Floodproofing of proposed structures would be required
through the Mason County Flood Hazard Ordinance, which must be adopted for the
county to enter the regular phase of the National Flood Insurance Program and
continue eligibility for flood insurance. No new channel modifications, dikes,
or diversion structures would be built for erosion control or flood reduction
purposes. The primary responsibility for flood evacuation would continue to be
carried out in an ad-hoc manner by Fire District No. 9.

Effects: The Skokomish River and tributaries would remain partially contained
in flood conditions by existing dikes. The river would continue to aggrade and
annual flood damages would increase with the increased intensity of flooding.

Private property: Individual floodproofing would reduce some flood damages.
Future development in the floodplain would not be restricted to flood compat-
ible uses, although residential development in the floodway would be prohib-
ited. Debris would continue to require removal from fields and roads.

Public property: Debris would continue to require removal from roads. Roads
would increasingly be impassable during flood events.

Public safety: Residents of the Skokomish Valley would continue to be exposed
to life, health and safety threats, and social disruption. Evacuation would be
difficult during flooding.

Agriculture: Soil erosion and crop damage would continue.

Fish and wildlife.resources: Existing habitat conditions would continue to be
affected by the aggrading river. Riparian habitat would continue to be lost to
a widening of the braiding channel.

Recreationi The widening and braiding of the Skokomish River would continue
and may increase the difficulty of recreational navigation in summer months.

Sedimentation and aggradation: Existing trends would continue.

Hydrology: Existing trends would continue. The frequency and severity of an-
nual flooding would continue to increase.

Implementation: As Mason County enters the regular phase of the National Flood
Insurance Program, new structures within the floodplain will be required to
floodproofed. Emergency response assistance will be provided without the ben-
efit of detailed flood preparedness plans. Homeowners will continue to
floodproof structures without technical assistance or adequate information on
flood heights.

Annual management: The federal government will continue to provide insurance

100

premiums subsidy. Mason County will maintain roads, right-of-ways, riprap, and
existing dikes, and provide emergency response assistance. Individuals will
maintain their floodproofed structures and repair flood damages without techni-
cal assistance on minimizing after flood damages and pay flood insurance premi-
ums.

ALTERNATIVE 2: EMERGENCY PREPAREDNESS
Description: A community's ability to effectively respond during flood events
depends upon the emergency preparedness measures that are in place. Both indi-
vidual and institutional provisions must be made prior to an actual flood event
for necessary actions to reduce flood damages and assure public safety.

Individual property owner action plans would consist of provisions for:
1. Auxiliary power
2. Evacuation plan by storm stage and degree of floodprone tendency by area
3. Flood preparedness plan for individual homes. This information would
be on file with the Fire District and Sheriff's Department and regular
drills would be conducted.
4. The current county emergency preparddness plan would add detailed response
measures, such as:
A. Preventative evacuation of persons with health or mobility
considerations.
B. Notice of power shut off or reconnection.
C. Post flood inspection process prior to residence reentry.

An automated flood warning system eventually could be developed to provide ad-
ditional response time for the early implementation of the individual and com-
munity emergency preparedness plans. The system would have a receiving station
for flood information, such as the County Sheriff's Department. Specific flood
warning information could be made available to floodprone residents through an
automated message system which would either dial resident's phones and transmit
a message or provide a phone number for residents to call for information on
flood stage and forecast.

Effects@. A certain amount of flood damage can be prevented with an adequate
and coordinated response plan and enough time for implementation.

Private property: Flood damages would be reduced, depending on the amount of
response time available to implement flood response measures.

Public property: Flood damages would be reduced, depending on the amount of
response time available to implement flood response measures.

Public safety: Public safety would be increased.

Agriculture: Soil erosion and crop damage may be reduced if management prac-
tices are altered. Agricultural structures would be better protected.

Fish and wildlife resources: No change.

Recreation: No change.

Sedimentation and aggradation: No change.

101

Hydrology: No change.

Implementation:
Federal - USGS technical assistance in developing or reviewing plans for an au-
tomated flood warning system. National Weather Service participation in
evaluating and distributing information from an automated flood warning system.

Mason County - Develop flood preparedness plan and make necessary organization
and structural changes as needed to effectively implement plan in a flood
event. Establish a local flood response center outside of the floodplain at a
location other than Fire District No. 9 station. Conduct flood audits on all
structures within the floodprone area of the Skokomish Valley.

Individual - Develop an individual flood response plan and implement all recom-
mended measures from a flood audit.

Annual Nanagement:
Federal - Possible National Weather Service participation in an automated flood
warning system maintenance.

Mason County - Regular review and practice of flood preparedness plans would be
necessary.

Individual - Regular review of individual flood preparedness plans.

ALTERNATIVE 3: FLOOD PROOFING OF STRUCTURES

Description: Many residential and agricultural or nonresidential structures
would be floodproofed to reduce flood damages through a combined public and
private effort. Floodproofing measures would include:
Elevating electrical and stored materials, elevating structures on fill or a
raised foundation, retrofitting closures, and constructing berms around
floodprone structures. Relocating structures out of floodprone areas in some
instances may be the safest and most effective approach.

To protect public transportation access during flooding, roads could be el-
evated. Provision for flood water movement would be necessary to avoid a dik-
ing affect*. A road improvement program, extending over a period of years,
would prioritize the most frequently flooded road areas.

Nonresidential structures would be modified so that all openings below the base
flood elevation can be made water tight or wet floodproofed. Flood insurance
would continue to be available and the rates would be reduced after
f 1 oodproof i ng.

Residents would need technical and financial assistance. Public assistance
would be made available through Mason County and other participating agencies
such as the Army Corps of Engineers and the Federal Emergency Management Agency
(FEMA).

1. Develop a plan to make financing available through grants or loans and
technical assistance for structural measures. This could be administered
through the county building department.

102

2. Surveys and benchmarks established with Army Corps of Engineers and FEMA
assistance.
3. Individualized plans for floodproofing structures developed with assistance
from a consultant specializing in flood reduction management.
4. Financial assistance provided to individuals.
5. Individual floodproofing measures conducted.
6. Public floodproofing measures conducted.

Effects: Flood damages and related flood hazards would be reduced sig-
nificantly.

Private property: Structural damages would be reduced. Skokomish Valley
residents would be better informed about flood damage reduction. The river
would continue to aggrade and annual flood damages would increase with the in-
creased intensity of flooding. Debris would continue to require removal from
fields. Future development in the floodplain would not be restricted to flood
compatible uses only. The cost of future development would initially be higher
if flood proofed.

Private Property: Flood damage to structbres would be significantly reduced.

Public Property: Road access would be improved during flooding.

Public Safety: Life, health and safety threats, and social disruption to
residents would be reduced.

Agriculture: No change.

Fish and wildlife resources: Existing habitat conditions would continue to be
affected by the aggrading river. Riparian habitat would not be altered by
instream flood control measures.

Recreation: The widening and braiding of the Skokomish River would continue
and may increase the difficulty of recreational navigation in summer months.

Sedimentation and aggradation: No change.

Hydrology: Existing trends would continue. The floodplain would continue to
dissipate flood water without restriction.

Implementation:
Federal - Establish base flood elevations for structures, provide technical
assistance in elevating and wet floodproofing of structures, as available
under the Corps of Engineers Flood Plain Management Services (FPMS)
Program.
Mason County - Provide technical through the building department. Finan-
cial assistance, such as a revolving loan fund, could be established for
financing individual floodproofing measures. Road access and emergency
response would be improved by measures such as elevating the roadway and
locating the flood response facility outside of the floodprone area of
the Skokomish Valley.
Individual - Finance individual flood proofing measures with outside
technical assistance.

103

Annual management:
Federal - None.
Mason County - Administration of technical and financial assistance,
maintenance of roads and right-of-ways, and provide emergency response.
Individual - Reduced insurance premiums and repairs of non-floodproofed
items.

ALTERNATIVE 4: STORAGE OF FLOOD WATERS

Description: Historically, wetlands constituted much o 'f the land within the
Skokomish Valley floodplain. The flood storage function of wetlands is becom-
ing increasingly appreciated as engineered stormwater detention facilities are
designed and constructed at great expense. Where remnant wetlands can be re-
tained or restored to serve the natural function of flood water storage, this
approach should be implemented prior to the development of more expensive and
higher maintenance flood storage options of man-made structures. A detailed
wetland inventory should be conducted of the Skokomish River watershed. The
inventory would establish current and historic wetland sites, evaluate current
and historic storage capacities, and determine potential areas for increasing
storage capacity through wetland enhancement.

1) Retention structures of varying capacities would be constructed in the South
Fork Skokomish River drainage basin and Vance Creek drainage basin. Peak flows
of flood water would be retained over a greater time period and would reduce
the amount of flooding experienced in the lower Skokomish Valley. Low stream
flow would be enhanced somewhat. In the early 1980's, a proposal was made to
establish a hydropower facility on the South Fork, which would have inciden-
tally provided some moderation of peak flood flows.

2) Lake Cushman - Lake Cushman provides storage and diversion of approximately
half of the water within the Skokomish basin. Some additional flood storage
capacity may be available, according to preliminary Corps of Engineers review,
although it is not anticipated to provide much relief during peak flood flows.

Effectsi' Peak flood flows would be reduced, although floods would have a
longer duration.

Private property: Flood damages would be less severe.

Public property: Flood damages would be less severe.

Public safety: Evacuation would be more feasible.

Agriculture: Flood damages would be less severe.

Fish and wildlife resources: Summer stream flows would be increased somewhat
which may improve fish habitat. Some spawning and wildlife habitat areas would
be lost to water impoundment. To the extent that existing wetlands are con-
served for flood water storage, fish and wildlife habitat could be maintained.

Recreation: Pond or lake-oriented opportunities may be increased.
Stream-oriented opportunities would be reduced by retention areas.

104

Sedimentation and aggradation: To the extent that instream detention struc-
tures are used, sedimentation of suspended and bed load materials would reduce
aggradation of the lower South Fork and upper main stem.

Hydrology: Peak flood flows would be reduced and water surface levels would be
lower while the duration of peak flows would be increased. The degree of in-
convenience would be less, but the duration longer.

Implementation: Depends on the scale and type of the proposed storage facil-
ity. Wetland acquisition and maintenance could be a multi-agency project.

Annual management: Depends on the scale and type of the proposed storage fa-
cility.

ALTERNATIVE 5: PIATERSHED MANAGEMENT

Description: Land use practices within the Skokomish watershed would be
evaluated to determine which activities may be accelerating surface water run-
off and contributing to increased peak flows and sediment transport materials.
Measures to reduce the impacts of land use activities in the watershed would
include;
1. Erosion control and remedial action throughout the watershed.
2. Vegetation management and revegetation throughout the watershed.
3. Upland sediment traps in ephemeral channels to slow water velocity over
bare soils and prevent soil migration.
4. Headcut control measures such as reducing slopes and seeding.
5. Identify sediment feeder areas such as bluffs and control if possible.
6. Retention and settling ponds.

We also recommend early adoption of the TFW agreements by the Olympic National
Forest, particularly with respect to closure of roads.

Effects: Long term slowing of the rate of river sedimentation and aggradation.
Channel braiding and debris build up would be reduced. Rate of increased
overbank flooding would be slowed.

Private property: Threat of continuously more frequent and severe flooding
would be reduced.

Public property: Threat of continuously more frequent and severe flooding
would be reduced.

Public safety: Private property: Threat of continuously more frequent and se-
vere flooding would be reduced.

Agriculture: Private property: Threat of continuously more frequent and se-
vere flooding would be reduced.

Fish and wildlife resources: Fish and wildlife resources would be improved to
the extent that they are currently adversely affected by channel braiding and
reduced channel capacity.

Recreation: No change.

105

Sedimentation and aggradation: Long term slowing of the rate of river sedimen-
tation and aggradation.
Hydrology: Peak flood flows might be reduced somewhat.

Implementation: An extensive and cooperative effort by private and public
property owners would be required to evaluate all lands within the watershed
and implement measures to reduce erosion and surface water runoff. Technical
assistance regarding erosion control, vegetation management, sediment traps,
and headcut control measures could be provided by the Soil Conservation Ser-
vice.

Annual management: Ongoing management by all property owners would be supple-
mented by a long-term monitoring program to evaluate the effectiveness of wa-
tershed management practices.

ALTERNATIVE 6: CHANNEL CAPACITY

Description: A perceived purpose of channel capacity maintenance has been to
reduce the amount of overbank flooding experienced in the main stem Skokomish
Valley. Channel capacity maintenance works include: restoration of lost capac-
ity in old meanders and side channels; removal of impediments such as unused
pilings; and gravel and debris removal.

Evidence shows that only minor or limited reductions of flood height can be
achieved through debris and gravel removal. The effect of channel restoration
is variable, and must be evaluated on a case by case basis. Since the Skoko-
mish Valley experiences overbank flooding on an annual basis, the containment
of major flooding through channel maintenance would require a channel capacity
which is environmentally impractical to establish, let alone prohibitively ex-
pensive to maintain.

A secondary, but, possibly more achievable, purpose for conducting channel main-
tenance is to reduce the amount of river braiding and bank. erosion occurring in
areas where river sediment materials accumulate. The potential of the main
stem Skokomish River to significantly change its course across the Skokomish
Valley makes channel maintenance a particularly challenging matter for Mason
County.

The reduced North Fork flows -- approximately half of the entire basin's flow
-- has potentially reduced the amount of sediment transported through the river
system and therefore may have increased the need for artificial or supplemental
channel clearing to maintain channel capacity. The reestablishment of minimum
flows on the North Fork may increase the channel capacity somewhat and there-
fore lessen the amount of material considered for removal from the river.

Channel maintenance would incorporate considerations such as removing sediment
and fill from blocked old meanders. An old meander system of the main stem
Skokomish River, flowing west of US 101 and north of the main channel (N 1/2,
Section 15, T21N, R4W), historically carried more volume but has been blocked
at both the inlet and the outlet. Additional channel capacity can be regained
by evaluating and restoring old meander systems.

106

Abandoned pilings in the lower reach of the Skokomish River main stem should be
removed to prevent the accumulation of log jams and resulting channels shifts.

The entire reach of the Skokomish River and its tributaries should be evaluated
to determine the most efficient locations for removing sediment from the sys-
tem. Where possible, sediment traps should be located at sites between the
initial source and the deposit area rather than merely at the point of deposi-
tion.

Effects: Bank erosion and river braiding may be reduced. The threat of a ma-
jor channel change may be reduced or delayed. Some minor reduction of flood
heights may be accomplished for frequent floods.

Private property: Bank protection measures may become less necessary if bank
erosion and river braiding are reduced.

Public property: Roads and bridges may be less threatened.

Public safety: The chance of road or bridge washouts may be reduced, assuring
that evacuation during flooding would be' feasible. Flood height would not be
notably affected.

Agriculture: Where bank erosion is threatening crops, these areas may experi-
ence a reduced rate of land loss.

Fish and wildlife resources: If conducted properly, fish and wildlife re-
sources would not be adversely affected. Increased channel capacity may en-
hance fish habitat. If the channel maintenance program included back channel
removal of materials, impacts would be limited. Drop structures in some in-
stances may enhance fish habitat.

Recreation: No change.

Sedimentation and aggradation: Sedimentation and aggradation would be to some
extent regulated or maintained at a lower rate.
k
Hydrolog y: The river channel may be more stable with sediments removed.

Implementation: Effective artificial channel maintenance requires that either
the current or an historic channel capacity throughout the river be estab-
lished. The rate of sediment movement and volumes of sediment material being
contributed to the rapidly aggrading river channel must be calculated to deter-
mine the degree of channel maintenance needed. A maintenance program should be
developed for the entire length of river experiencing altered channel capacity.
This would include estimates of material to be removed at various
cross-sections and a regular schedule for removing the material at specific
sites. Long-term monitoring of the bedload amount and channel capacity would
be a part of the channel maintenance program.

Annual management: Mason County would have to commit significant financial re-
sources to a regular channel maintenance program. The large volumes of
sediment materials to be removed from the Skokomish River floodplains would
probably require a large commercial use on the scale proposed by Hamma Hamma
Sand and Gravel for a location on Hood Canal.

107

Individual efforts could effectively supplement a river-wide channel mainte-
nance program.

ALTERNATIVE 7: DIKING

Description: Diking can effectively reduce the amount of flood waters experi-
enced, depending on the structures height and frequency of flood protection
provided. The current diking in the Skokomish Valley provides flood relief to
an undetermined flood frequency. Along the Vance Creek it has been reported
that no flooding has been experienced since the dike running along the bank was
constructed. It should be established just how much flood water can be accom-
modated before overtopping or breaching occurs. Even more severe flooding can
occur when that level of dike protection is exceeded. Also, no regular dike
maintenance or inspection has been conducted. Mason County should acquire this
information so that any preventative maintenance or dike improvements can be
made.

The existing diking in the lower Skokomish Valley is incomplete and allows an-
nual flood flows to cut around the end of one reach of dike. There is a pos-
sibility that the partial diking is diverting and focusing the flood flows into
a more narrow area and causing more severe erosion at the end(s) of the diked
area. Rather than shallow sheet flows over a broader area, the velocity and
volume of the flood flows through the undiked area may be creating more of an
overall threat of catastrophic channel change.

These concerns related to the existing dikes should be addressed be any propos-
als for additional diking are considered. The appropriate alignment for any
diking within the lower Skokomish Valley should take into account the level of
flood protection sought, necessary internal drainage systems needed for diked
area, upstream and downstream impacts of diking, the necessary ongoing mainte-
nance of such structures, possible improvements that may be needed as the river
continues to aggrade, comparison of diking to other floodproofing measures.
It may be more appropriate to floodproof structures or construct localized
berms or dikes around compounds of structures, with the provision of internal
pumping,.of surface waters.

Effects: An effective diking system could provide substantial relief from
low-frequency to high-frequency flooding and reduce flood damages.

Private property: Structural damage from flooding could be minimized.

Public property: Road and bridge access could be improved during flood events.

Public Safety: Evacuation during flood events would not be necessary.

Agriculture: Soil loss and crop damage would be reduced.

Fish and wildlife resources: More intense instream flood flows could adversely
affect fish and wildlife resources.

Recreation: River access would be affected

Sedimentation and aggradation: The effects of diking are not readily

108

predictable, and would vary depended on the extent and design of the diking;
effects could be beneficial or adverse.

Hydrology: The effects of diking are not readily predictable, and would vary
depending on the setback of the dikes from the main channel.

Implementation: An evaluation and design of the appropriate dike alignment and
an environmental impact statement would be required.

Annual management: Construction and maintenance of dikes would be a very re-
source intensive flood control measure but will result in a substantial reduc-
tion of flooding to the south side of the Skokomish Valley. The tendency to
divert erosion downstream would be increased.

ALTERNATIVE 8: BANK STABILIZATION

Description: The term, bank stabilization, encompasses a wide range of measures
intended to prevent soil losses from slopes and streambanks. Slope regrading
and bank hardening with rock revetment,-concrete lined channels, and intensive
vegetation planting with or without revetments are some of the more commonly
constructed bank stabilization projects. On the Skokomish River where the
streambed has been braiding or widening significantly, a streambank maintenance
program needs to be practiced for the entire length of the river and, ideally,
the tributaries. This would be coordinated through Mason County, with ease-
ments or acquisition of land to assure continued access and maintenance. Chan-
nel maintenance and sediment removal need to be practiced for bank stabiliza-
tion to be effective long term.

Instream approaches to reduce bank erosion such as sediment traps or drop
structures should be evaluated and,, where appropriate, constructed.

Historically, measures such as rock and timber revetments have been placed on
eroding banks, as well as trees being cabled downstream into the river to
deflect current. Vegetation has been planted to stabilize and protect threat-
ened slopes. In many instances these measures have been effective in slowing
or eliminating soil loss. Diversion dikes and river bar scalping have also
been practiced on the Skokomish River and Vance Creek. Maintenance of most of
the bank stabilization efforts has been by local land owners, individually and
collectively as resources were available.

Effects: Reduce soils and land lost due to river braiding. Reduce threat of ma-
jor channel change.

Private property: Reduce loss of land.

Public property: Reduce loss of land and threat to roads.

Public safety: Reduce possibility of road washouts.

Agriculture: Reduce soil and land loss.

Fish and wildlife resources: May reduce streambank cover through bank harden-
ing, or enhance habitat if biotechnical measures are adopted.

109

Recreation: No change.

Sedimentation and aggradation: Reduce sedimentation from bank erosion, a minor
source of aggradation.

Hydrology: Bank hardening may divert velocities to downstream locations.

Implementation: Mason County would determine and obtain the needed easements to
effectively maintain streambanks through whatever site-specific measures of
stabilization are chosen throughout the system. In most cases, cooperative ef-
forts can be established with property owners. In some instances, relocation
of residences may be necessary.

Annual management: Maintenance of streambanks will be a very resource intensive
flood control measure but will result in a comprehensive approach to bank ero-
sion. The tendency to divert erosion downstream will be reduced. Continued
individual efforts will assure that problems areas are identified quickly and
maintained regularly.

ALTERNATIVE 9: INSTREAN DIVERSIONS IN CRITICAL AREAS

Description: Spur jetties or deflectors can divert flows in critical areas,
such as the proposed design by Wolf Bauer for Mason County. Instream drop
structures are another method for diverting flows to secondary channels. These
measures and their instream impacts must be evaluated in relation to the value
of the area of concern. These structures would be considered in conjunction
with channel maintenance and streambank stabilization efforts.

Effects: A localized diversion of flows would protect critical, intended sites
such as roads. The erosion would possibly be diverted downstream to another
location. A major benefit would be experienced, to the extent that a diversion
structure would assist in reducing the likelihood of a major chahnel shift.

Private property: Significant protection may be provided to private property,
especial.ly where a major channel shift if prevented.

Public property: Significant protection may be provided to roads and bridges,
especially where a major channel shift is prevented.

Public safety: The benefit of reducing the threat of a road washout or major
channel shift is a primary consideration in stream diversion measures.

Agriculture: A major channel shift could have a substantial impact on agricul-
tural lands.

Fish and wildlife resources: Little or none.

Recreation: Structures may reduce access to river.

Sedimentation and aggradation: Location of deposited materials would be al-
tered. Bank erosion would be reduced somewhat with proper design; improper
jetty design can have adverse bank erosion effects due to back scour.

110

Hydro7ogy: Diversion structures generally have no effect on flow volumes, but
do locally redirect stream flows to alleviate bank erosion.

Imp7ementation: Mason County would have detailed project plans developed and
would address environmental issues, as raised for previous proposals, through
the services of a consultant. These issues include an evaluation or modeling
of the project's effectiveness in accomplishing the channel stabilization; an
analysis of effects upon downstream lands and fish and wildlife habitat; and
proposed mitigation measures.

Annual management: A regular maintenance program would be required, including
the possibility of extensive, ongoing repairs or additional structural measures
to hold the channel in a specific location.

LONG-TERM RECOMMENDATION
The foregoing planning alternatives all address emergency and/or short term
needs and issues. Without long term planning designed to address the problem
of river bed aggradation, none of the immediate or short term measures can had
any substantial value. Following is a gummary outline of the components of a
long term approach to addressing aggradation and flooding in the Skokomish Val-
ley.

1) Evaluate South Fork Skokomish River basin erosion rates from:
general landscape
unvegetated area
roadways
debris slides,-slope failure
This information can be derived from available data, photos, etc. to establish
an average estimated input to the river system.

2) Locate and map slope failures on and near the South Fork and tributaries
and evaluate input rates to the river system.

3) Evaluate general bank erosion and estimate contribution to sediment load.

4) Measure suspended solids transport in the South Fork at USGS gage 12-0605
at South Fork RM 3.1 for one water year and correlate measurement with runoff,
rain or snow pack.

5) Evaluate bedload transport into main stem by means of available data --
aerial photos -- and if possible, topographic measurement.

6) Estimate sediment loading of main stem under natural and existing condi-
tions and project the future effects of that rate on the river bed
geomorphology under existing conditions and modified land use practices.

7) Develop and evaluate alternatives for handling the sediment load, including
but not limited to:
no action
land use practices in the South Fork basin
sedimentation trap(s) in the South Fork basin
channel management in the Skokomish Valley

The study should be carried out by an independent consultant with the
assistance of:

1) Ecology - floodplain management
- water resources program
2) Fisheries - habitat management
3) Natural Resources Forest practices, TFW agreement
4) Corps of Engineers flood management
5) FEMA - flood management
6) Fish & Wildlife Service - fisheries
7) Skokomish Tribe - fisheries, flood management
8) US Forest Service - forest management
9) USGS - hydrology

It is important to remember that it is difficult if not impossible to measure
bedload transport. Thus the most practical procedure may be to construct one
or more "temporary" sediment traps and monitor the rate of filling over a few
years as a means of estimating bedload transport. Based on this experience, a
11permanent" solution may then be designed.

SUMMARY AND CONCLUSION
A multi-agency task force should be established to assist Mason County in es-
tablishing and implementing a work'program of flood control management mea-
sures. The problems and issues that are being experienced in the Skokomish
Valley are not so unique and isolated that they remain only a local problem.
Emergency response agencies and resource agencies alike share in the concerns
that the people of Mason County have about flooding on the Skokomish River. It
is hoped that the discussion in this study will further the ongoing dialogue
between those entities with technical expertise and those in need of assis-
tance.

112

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MT. TEDO, 190

PORTIONS'OF RIVER UPDATED BY MOTO INTERPRETATION
FROM IW7 PHOTOGRAMY.

T22N QLY-C NATI@AL FOREST KWN@R! T22
'Hl -N T2

Lk.
T-e 3

4 3 2 17-

Fw I-

----------

- ----- SKOKOMI
SH
2 1.7

0
IS
", 4-04,
04,,

11c

Mok-is
Is
15 14 17 is
13 T- =-, lCoAlls 6
VALLEY
------- 0A
If

21
22

NORTH
FORK

Mc TAGGERT
CREEK

CUSHMAN RESERVOIR

NO. 1 CUSHMAN DAM &
DIVERSION CUSHMAN NO. 1 POWER PLANT.
DIVERSION DAM DEER (1926)
(1953) MEADOW NORTH
CREEK FORK

KOKANEE

LAKE
'Mc TAGGERT-
CREEK CUSHMAN NO. 2 DAM
(1930)
DEWATEREDI"jo"l
MINIMUM FLOW EXCEPT DURING DIVERSION
0.5 cfs STORM FLOW
EXCEPT DURING CUSHMAN NO. 2
STORM FLOW HOOD
POWER PLANT
(1930) CANAL
NORTH
FORK

SOUTH FORK SKOKOMISH RIVER
USHMAN No. 2 @DA M
1930)

G D IVERSION

,IVER

Figure 4.1

DIAGRAM OF CUSHMAN PROJECT DIVERSIONS.

BASE DATA:

U.L,GEOLOG#CAL SURVEY 75 MINUTE OUADRANGLE SERIES
MAPS AS FOLLOWS;
SKOKOMISH VALLEY 190 PROVISIONAL EDITION F
UNION. ion rwwtsi6i@AL EDITION F-
T14E FOLLOWING ISMINUTE QUADRANGLE SERIES MAP,
A PORTION ENLARGED APPPIOX 2W%;

MT. TESO, 1963

PORTIONS OF RIVER UPDATED BY PHOTO INTERPRETATION
FROM IW? PHOTOGRAPHY.

T22N NATI@AL so@@py T2
T21N LEGEND: T2

DIRECTION OF FLOW DURING ANNUAL FLOOD.
T@o 3 EXISTING DIKES

AREA OF ANNUAL FLOOD PONDING
4 3 2 AERIAL PHOTOGRAPHY OF MARCH 4. 1987.

1 5 K 0 K 0 M I S H
2 11
9 10
7 -j
10

12 T5

MohrWeilj 2@16
15 14 si,017
13
1<1 T. If 0 s
V A L L E -M,

G-p

21
22
L7

-100 YEAR FLOOD@PLAIN

FLOODWAY FLOODWAY
FRINGE IN. FLOODWAY FRINGE

STREAM
CHANNEL

FLOOD ELEVATION WHEN
CONFINED WITHIN FLOODWAY

ENCROACHMENT NCROACHMEN-
C\ D .......
E
SURCHARG
A
B

AREA OF FLOOD PLAIN THAT C )ULD FLOOD ELEVATION.
BE USED FOR DEVELOPMENT BY BEFORE ENCROACHMENT
RAISING GROUND ON FLOOD PLAIN'

LINE AB IS THE FLOOD ELEVATION BEFORE ENCROACHMENT;
LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT.
*SURCHARGEIS NOT TOEXCEED 1.0-FOOT (FEMA REQUIREMENT)

THE CONCEPT OF THE FLOODWAY

THE "FLOODWAY" IS AN ENGINEERING CONCEPT WHICH HAS BEEN INCORPORATED INTO THE NF 'P
FLOODPLAIN MANAGEMENT CRITERIA. FLOODWAYS ARE DEFINED AS THE AREAS OF LAND
IMMEDIATELY ADJACENT TO A STREAM OR RIVER CHANNEL WHICH IN TIMES OF FLOODING
ACTUALLY BECOME THE ENLARGED STREAM OF RIVER CHANNEL AND CARRY THE FLOODWATERS
WITH THE HIGHEST VELOCITY. FLOODWAYS ARE CALCULATED BY FEMA FOR THE "00 YEAR BASE
FLOOD FOR MAJOR RIVERS AND STREAMS AS PART OF THE FLOOD INSURANCE STUDY UNDERTAKEN
FOR A COMMUNITY. FLOODWAYS ARE SHOWN ON, THE COMMUNITY'S FLOODWAY AND FLOOD
HAZARD BOUNDARY MAP PREPARED BY FEMA, AND DATA ON THEIR WIDTH, CROSS-SECTIONAL
AREA AND FLOOD-WATER VELOCITY ARE GIVEN IN THE FLOOD INSURANCE STUDY. WHEN
FLOODWAY DELINEATIONS AND DATA HAVE BEEN FURNISHED BY FEMA, THE COMMUNITY IS
REQUIRED TO ADOPT A "REGULATORY F LOODWAY" AND BEGIN ENFORCING THE "NO-ENCROACHMENT"
REQUIREMENT THROUGH ITS ZONING ORDINANCE.

Figure 6.1

FLOOD PLAIN SCHEMATIC CROSS SECTION.

__X

I @4A

Nft.
nwA y

VvEAV
_W9A

2id

,V,4.A4*

'FLOODWAY
FL
z

-2q

M M Mfture@ F@DV4MWNUWOMY FMWE.M M M M M

r
P-1- Ti

tot,
ft,

0
GA DAM'
T4, 7p.
eIf
OODWAY a,:
FR GE
FL

............

SK0KVMd1?
:R1. VT
PIN
J,3

'47
LOODWA Y.r,
F

Wre MM FWWA"ND MOD" FWE.

W 4--
FLOODWA Y

F0ObWA.-y,`-*-
gig

'(p'- -4. -

OOD
VALLEY

'- 4@r

FLOODWAY

z
So 0

Fi9%WA.."ODW A%"LOMAY"NG@.

"Woo'

�A
ODWA Y F TCH
RING
FLOODWA

ej
-'FL OOD WA Y
WE*,

16% lh

bKOMIS

FLOODWA Y

T
ri

ogo
s
K
ire r4

i'jj
AN
a
Film 4A. &OO"Y A&FLOWAJ"lNCf.

VIA` k-Apyl;

LMO
k-CH

100
JFLOODP IN

Tlk
7aw.
Lgq&@

FLOODWAY FRING

y
FLOODWA

R
AY@@'-
0

kl
ST
Sa

qok
k-OR
@V.

m FMW 51OW-OCWWY JW FLJWWAaWINVE M M M M

bod-W

WIN"

AA
t6
n-VW

............ .

Y
WA @RINGE

SKOKOMISH- VALLEY
Z@o

ST04TION

q
FLOODWA Y.

FLD
k.F

M M FidMA. @OrMW AIWLC@AMMN@ M M M M M M

:4
40

4=
7
@y FIL

Alm,
wAY FRINGE SKOKOMISH
4
0 m
UNITY

Al
MISH,
v4LLEY I ROAD

.4@

b" A,
i!-V
4,

OB
11U

-,2

Figure 7A. FLOODWAY AND FLOODWAY FRINGE.

';* 01

F& 7 WA Y

AqX
how"_.
6MIS14
VAL @'E
Um
-N' 16# D-
N'.
UMI 7' 0
Ar-i IF DETA
IL ED
SKOJVC
4

4
I, "o

f Vic

oil

-ja

Figure 8A. FLOODWAY AND FLOODWAY FRINGE.

q,j

pj
IN 4f
*v

IDA&. 7wi
-A

op z /,v 9- -Y&/
Xro

Figure 9A. FLOODWAY AND FLOODWAY FRINGE,

liL

77
IA
& f4 ei*w
II"OtACli., 0

_%p
AV,

MVE

X5,00.

Figure 10A. FLOODWAY AND FLOODWAY FRINGE.

WIk"
N'l
Vol, R E
MOW. -
T, v Tr@ A
0", W-11
;p-

-_4 If T Ar IT---

IT I
4A t

44 4

J?;7 40

Figure 11A. FLOODWAY AND FLOODWAY FRINGE.

k5'

Figure 1B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC. 12, T21N-R4W, RM 1.2-1.4.

C.7

IF o-j,
ye
v,
- '_ v

to
Al

eil

Figure 2B. EROSION, D EPOSITION AND. POTENTIAL FLOOD DAMAGE,
SEC. 12, T21N-R4W, VICINITY OF SR 106, RM 2.2.

All

Al-

.4i
p It

@A
sot

e.r-

't't

Iz
IN't
'cl

;ej

Ic 4r
IMA

Figure 3B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC. 14, T21N-R4W, RM 3.6-3.8.

-It

j
4@

'7@

kp;

'1')

'1% f r

fo, .0 im"
4.1 1'
OU 'V-

'f'
nol@ Jfa-

Figure 4B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC 12&13, T21N-R4W, RM 2.4-2.7.

A4
fT4 T"

71.
SKO
Ko&jj@
SH
zLm WOO

-V.
0T&VT1A'L-:'F E

Figure 5B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC 15&16, T21N-R4W,
WEAVER CREEK AT SKOKOMISH VALLEY ROAD.

W:T

@ avvpj@ ;@

Figure 6B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC 15&16, T21N-R4W, RM 5.7-6.1.

t' Zk t

tP
..f

41
V

,It
Aw

ef.

L 1,

X':

J'o
00
@t4-rlA Ge
/* POT AMA

-go
I- W" @00'0.
jf

Figure 7B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE, SEC 15, T21N-R4W, RM 5.4-5.5.

Ile AT

el
'NOR

tv
-j's. 4%1 -1 1

do.
V.L I -- . . !1. 1

j7
jr
10>

41bAl

TENTIA L!

11, All

.011 lm@ 16 .4
Z.7. i

Jr -Z
4 RV

it,

4A,*,

aA
xd_
;yj

@ n-tt

'lie

-z..k-

Figure 9B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE,
@plo`

SEC 9, T21N-R4W, RM 6.7-6.9.

LEY

r'A

TEN

DEPOSI
TI

Ilk
z@,
I'.,-- vtllt
-Ij

kKel&,ERWWN,JWSI&WAVMOTWWALIWOD"A%dECJWlN@&W,IW.5-fob M M

NOV
At':

i e

"e3,

DEPOSITION

_i7 -
MW

Xt ;W-;@

igu"B. IWSIQ"EPJWIOWD P,6VNTJ&FLCJ&DAWWE, JW6,Y T21-IM RI"-61100

-EZ

FLOO VALLF- J
ROAD
D Y5
j@079NT A..,.
Sk6KOM
FIRE
7:3
'TATION

jHALL1.

;X7.

if"A

E' I I&M ERWWN, %WSIJM At*WTEMWL JWD JWAG&JEC jWl NaW,
aff m J&7.4m m

D
EPOSI

-AL
'Ak'
-Al
C 7::@

flSTAMA

�R;@
.fl,
OWN
Ko
Ali
It"t. l." -
17f
7p

'@'; W-0
"'OAO,

urejfi EJWON"POS"NA"PO"TIA6600&WMA&,SEJWECJWlN"W,WW-9-"

@W'

@InAl F

t
-Ck777@
Pr

ass.
%e:X

Jd.

f W.
H @W
@@SKOKOMIS
'COMMUNITYA
CHURCH
f lk
-2

.NW

MA(W

ILI

.61
4 ;C!.4,w
tall
.IV-

14&,ER"N,JWS[IMAWTEWLfWD&WAG&WCJJJ21WW,"8.2.M

_Ile
D.EPOSITIONI

Z-a 7---

@@l oq

t @ MR _=j

ov
_tq

Figure 15B. EROSION, DEPOSITION AND POTENTIAL FLOOD DAMAGE,
SEC 11&12, T21N-R5W, LOWER VANCE CREEK.

A
'DEP0@31TION".""'."

,zs

D
EPOSITION

Fi"16E64ROJW, DJWITIJWND POTENTIAL FLOOD DAMAGE SEC 1 T21N-jo, RW, SW FW&

JOAA COASTAL SERVICES CTR LIBRARY
3 6668 14110330 1