Palco Marsh Enhancement Plan

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

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PROJECT INFORMATION

Project Name: Palco Marsh Wetland Enhancement Plan

Project Sponser: City of Eureka
Eureka, CA 95501
(707) 443-7331 ext. 309

Landowner: City of Eureka

Assessor's Parcel Numbers: 7-031-01
7-013-03
7-051-01
7-041-01 (Portion)
7-051-03 (Portion)
7-061-01
7-071-10

Project Size: 86 Acres

Zoning: Natural Resource (City of Eureka LCP Adopted July, 1984)

Project Location: Sections 28 & 33, T5N, RIW,.H.M.

City of Eureka City Council Approval September 29, 1987

TABLE OF CONTENTS

Page
1.0 ENHANCEMENT PLAN SUMMARY

1.1 Introduction 1-1
1.2 Description and Location @1-2
1.3 Site Analysis 1-2
1.4 Enhancement Plan 1-3

2.0 PROJECT DESCRIPTION

2.1 Introduction 2-1
2.2 Site Definition 2-3
2.3 Related Projects and Properties 2-5

3.0 SITE CONDITIONS

3.1 Topography & Geology 3-1
3.2 Soils 3-2
3.3 Hydrology 3-4
3.31 Tidal Influence / Surface Runoff 3-4
3.32 Flooding 3-6
3.33 Water Quality 3-9
3.4 Vegetation 3-13
3.41 Overview 3-13
3.42 Vegetative Description 3-14
3.421 Salt Marsh 3-14
3.422 Brackish Marsh 3-15
3.423 Freshwater Marsh 3-15
3.424 Riparian Wetlands 3-16
3.43 Rare Species 3-16
3.44 Invasive Species 3-16
3.45 Influencing Factors 3-19
3.5 Wildlife 3-21
3.51 overview 3-21
3.52 Salt/Brackish Marsh Area 3-21
3.53 Freshwater/Riparian Marsh 3-25
3.54 Use by Mammalian Species 3-25
3.6 Mosquito Vectors 3-26
3.7 Land Use/Access 3-28
3.71 Site History 3-28
3.72 Current Land Use 3-29
3.73 Access @-31

US Department Of Commerce
NOAA Coastal Services Center Library
2234 South Hobson Avenue
Charleston, SC 29405-2413

4.0 ENHANCEMENT PLAN

4.1 Introduction 4-1
4.2 Site Analysis and Goal Development 4-1
4.21 Topography, Geology, Soils 4-1
4.22 Hydrology 4-2
4.23 Vegetation 4-2
4.24 Wildlife 4-3
4.25 Public Access 4-4
4.26 Maintenance 4-4
4.3 Proposed Enhancement Plan Summary 4-5
4.31 Palco Marsh Complex 4-5
4.32 Paved Drying Shed Area 4-5
4.33 Area West of Railroad Tracks 4-6
4.4 Alternatives Considered 4-6
4.5 Proposed Enhancement Plan -
Construction Aspects 4-7
4.51 Palco Marsh Complex 4-8
4.52 Paved Dry Shed Area / Railroad Marsh 4-15
4.53 West of Railroad Tracks 4-16
4.6 Operations/Maintenance 4-17
4.7 Monitoring 4-18
4.8 Permit Requirements 4-20
4.9 Future Enhancement Work 4-21

REFERENCES R-1

LIST OF APPENDICES

Appendix A - Notes on Circulation and Sedimentation A-1
B - Vegetation Description/Species List B-1
C - Estimated Construction Costs C-1

MAP 1 Enhancement Plan Back Cover

FIGURES AND TABLES
FIGURES Page

1 Project Site Location 2-2
2 Palco Marsh Project Area 2-4
3 Tidal Exchange Area 3-5
4 Watershed Areas 3-7
5 Water Levels in Marsh
present conditions 3-10
6 Rare Species 3-17
7 Invasive Species 3-18
8 1939 Aerial Photo 3-30
9 Enhancement Plan - Tidal Prism/
Storm Runoff
a. Tidal Prism 4-9
b. 2-year Storm 4-9
C. 100-year Storm 4-10
d. Feb. 1986, Water Levels 4-10
10 Enhancement Plan - Tidal Exchange Areas 4-11
11 Enhancement Plan- Conceptual Phase Two 4-22

TABLES

1 Soil Salinities/PH 3-3
2 Drainage Areas 3-8
3 Water Quality 3-11
4 Avian Species List 3-22
5 Mammals List 3-23
6 Enhancement Plan -
Response to Tide 4-12
7 Enhancement Plan -
Response to Runoff 4-12

RAPS

I Enhancement Plan Back Cover

The following maps are available for review at the City of
Eureka and are at a scale of 1 inch equals 100 feet.

I Enhancement Plan
2 Topographic Map
3 Vegetation Map

1.0 SUMMARY

1.1 Introduction

The Palco Marsh has been a focus of concern for enhancement
activities by a number of agencies; the Army Corps of Engineers
designated the site as an "Area of Importance" to the functioning
of the Humboldt Bay ecosystem; the California Coastal Commission
included the Palco Marsh on its list of priority public acqui-
sition sites; and the City of Eureka designated this site in its
Local Coastal Plan for acquisition and enhancement activity, and
requested funding from the Coastal Conservancy for acquisition
and eventual enhancement improvements.

The Coastal Conservancy agreed to provide funding to acquire,
plan and restore the Palco Marsh site with three primary
objectives:

1. Enhance tidal action in the Palco Marsh.

2. Remove fill in drying shed area and restore to marsh
habitat.

3. Assemble land in the project area to improve future
management.

The development of the following Enhancement Plan takes into
account agency goals, site condition, and subsequent discussions
with the City of Eureka, the Coastal Conservancy and other
interested agencies.

Section 2.0 describes the project site location and its
relationship to other projects. Section 3.0 includes a site
inventory and identification of Marsh enhancement opportunities
and constraints. Section 4.0 contains the principal findings,
opportunities, constraints and goals developed from this
information.

Information compiled in this report was gathered from September,
@986 through February, 1987. Technical information has been
included, where appropriate, but for brevity's sake, is
referenced as separate studies available from the City of Eureka.
Development of goals and objectives proceeded from the Coastal
Conservancy's initial goals and were influenced by opportunities
and constraints inherent to site conditions. These goal s were
further defined through discussions with the City of Eur*eka, the
Coastal Conservancy and the California Department of Fish and
Game.

1.2 Description and Location

The Palco Marsh project site is located on the eastern shoreline
of Humboldt Bay at the western edge of the City of Eureka. It is
surrounded by urban development of three sides: 1) Del Norte and
Hawthorne Streets and adjacent commercial/industrial uses to the
north; 2) Broadway Avenue with commercial uses to the east; and
3) the newly constructed Bayshore Mall to the south. Wes-t of the
Palco Marsh project site are Humboldt Bay mudflats, central chan-
nel and the Samoa Peninsula. The Crown Simpson pulp mill is
located directly across the Bay channel on the Samoa Peninsula,
1/2 mile west of the subject property.

The project is bisected by the Northwestern Pacific Railroad
right-of-way, which traverses north-south across the project
site. The east half of the site consists of approximately 45
acres which includes a six acre developed area and a 39 acre
marsh complex, consisting of approximately 17 acres of salt
marsh, nine acres of brackish marsh, eight acres of freshwater
marsh, and five acres of riparian habitat. The western half of
the project site, 41 acres, consists of tidal flats, a shoreline
strip of salt marsh and a four acre upland peninsula located just
south of the end of Del Norte Street.

1.3 Site Analysis

Marsh topography, soils and off-site hydrologic conditions have
not changed much from historical conditions. Vegetation is more
sensitive to changing environmental conditions, and thus reacts
more quickly to changes. Because of this, opportunities are
available to improve the vegetation and consequently wildlife
habitat values. There are certain factors causing the marshes to
be under stress and affecting the marsh vegetation density.
These include poor tidal circulation and retention of storm run-
off which causes hypersalinity and dissolved oxygen depletion.
The unhealthy condition of the salt marsh is evident by the lack
of diversity of the vegetation. Under an improved tidal regime,
salt marsh areas could be returned to a higher functioning value.
Information gathered at the drying shed area indicates that,
depending on the amount of fill removed and the availability of
future water sources, this area could support wetland vegetation.
The major problem with the Palco Marsh with regard to wildlife
use is the lack of tidal circulation in the salt marsh and the
lack of significant amounts of open water habitat in the brackish
and freshwater marshes. This results in reduced food production
for all species of water-related birds and in a lack of water
surface for landing and take-off for certain waterfowl species
(e.g. ruddy ducks, greater scaups, cootst and grebes). The
outcome is both reduced numbers and diversity of wildlife.

Improving the circulation of tidewater throughout the salt marsh
will improve its value to wildlife. The lack.of circulation in
this area causes low food availability for wildlife. organisms

1-2

normally associated with salt marsh (and good circulation) are
present in limited areas within the Palco Marsh. These include
invertebrates which are critical for foraging by shorebirds,
snowy egrets, etc. An increase in tidal flows would allow the
redevelopment of this invertebrate fauna; subsequently the
diversity and numbers of wildlife in the area should increase.

Since mixed commercial/industrial land uses surround the project
site, adequate buffers are needed to protect/enhance the
integrity of the marsh environments. The site, at present, has
uncontrolled access and is used in ways contrary to wildlife
values. As the project site is restored for wildlife, increased
interest and subsequent use by the public is anticipated.
Providing controlled access for compatible public uses will be
necessary to maintain wildlife values for the site.

1.4 Enhancement Plan

The improvements necessary to accomplish the project goals
include both improving conditions in the existing marshes as well
as creating wetlands in non-marsh areas. Control of water within
the marsh will be accomplished by the placement of larger
diameter culverts at a lower elevation and channel excavation
within the marsh. Water levels in the marsh will be adjustable
by weir structures on either end of the culvert. This will
increase tidal circulation, and run-off drainage out of the
marsh. Clearing a one and a half acre area of cattails and
excavating a deep open water area will provide a more diverse and
much needed addition to the surrounding marsh habitats.

The RR Marsh will be graded with channels connecting into the
Palco Marsh drainage. Portions of the paved area, as well as the
railroad spur, will be graded to wetland elevations.

The remaining paved area will be enhanced as a "Phase 2" for this
project at a time when adjacent water sources become available
and/or as part of wetland mitigation for development of an
adjacent coastal dependent industrial parcel (Parcel 4).

Riparian vegetation will be utilized to screen and buffer
adjacent land uses, road edges, and parking areas. Public access

1-3

will be encouraged on the site in ways compatible with wildlife
needs. Access to the site will include two main entrance
locations, connected to each other by a pedestrian trail.
Viewing areas, benches and a picnic site are included in the
improvements. Access barriers will be provided in necessary
locations and signs will provide both educational information and
site use regulations. Riparian vegetation will be utilized to
screen and provide a buffer from adjacent land uses.

Project maintenance will be minimum and consist of inspecting and
maintaining water circulation improvements and public access
areas. Completion of the construction phase is only the
beginning phase of this project. Monitoring hydraulic,
vegetation and wildlife changes, as a result of this project, is
an important aspect to the project, both in research value and
for fine-tuning the marsh to ensure a "successful" enhancement
project. Completion of base data will be necessary prior to
construction.

1-4

2.0 PROJECT DESCRIPTION

2.1 INTRODUCTION

Humboldt Bay has experienced a loss of approximately 90% of its
wetlands. Out of a total of 6t5OO acres in existence in the
1800's only 600 acres of salt marsh and 40 acres of freshwater
marsh remained as of 1980. Recent restoration efforts,@funded
for the most part by the State of California, have increased
these figures to approximately 700 acres of salt marsh and 100
acres of freshwater marsh.

Several agencies have been involved in direct efforts to restore
wetland areas or enhance degraded wetlands around Humboldt Bay.
These include the California Coastal Conservancy., California
Department of Fish and Game, and the U.S. Fish and Wildlife
Service. Other agencies, such as the California Coastal
Commission, California Department of Fish and Game, Army Corp of
Engineers, and locally, the Humboldt Bay Harbor, Recreation and
Conservation District as well as local municipalities regulate
development affecting wetland or marine resources.

The project area has been an area of concern to.a number of agen-
cies. In 1980, the Army Corps of Engineers comp leted an
exhaustive inventory of Humboldt Bay wetlands and designated
areas into categories based on their resource values
(Humboldt Bay Wetlands Review and Baylands Analysis, Shapiro,
1980). The Palco Marsh project area was designated in this
report as an "Area of Importance" because of its importance to
the functioning of the Humboldt Bay ecosystem. The California
Coastal Act mandates wetland protection and enhancement where
feasible. As a result, the Coastal Commission included Palco
Marsh on its list of priority public acquisition sites and sup-
ported the City's application for funds to acquire and enhance
the site.

The City of Eureka's Local Coastal Program identifies specific
areas for wetland restoration projects within City limits. The
objectives of the program include enhancing the biological
productivity of the wetlands, minimizing or eliminating conflicts
between wetlands and adjacent urban uses and providing stable
boundaries and buffers between upland habitat areas. The Palco
Marsh project site is specifically mentioned for wetland restor-
ation.

The California Coastal Conservancy had been interested in pur-
chasing the marsh complex for a number of years. Discussions
with,representatives from Pacific Lumber Company (the landowner)
@ed to an agreement to preserve the integrity of the marsh. This
included Pacific Lumber Company (PALCO) divesting their entire
land holdings in the project area.

2-1

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PROJECT SITE LOCATION

2-2 Figure

In 1986 the Coastal Conservancy provided the City of Eureka with
the funding to purchase the Palco Marsh project site. Following
acquisition, the City of Eureka dedicated an open space easement
over the Palco Marsh project site to the Conservancy or a manage-
ment entity approved by the Executive Officer of the Conservancy.

In addition to providing funding for acquisition of the Palco
Marsh project site, the Coastal Conservancy will be inVolved in
funding a project that enhances this area. Enhancement, as out-
lined by the Coastal Conservancy, would include improving tidal
action to the 39 acre marsh complex, removing fill on a six acre
parcel, and assembling parcels of land to improve the resource
management of the project area. To this end, the Conservancy
provided funding to the City of Eureka to develop an Enhancement
Plan. Omsberg & Company and Rising Sun Enterprises were
contracted to complete a site analysis and develop the Enhance-
ment Plan for the area. A project team was compiled to assist in
this endeavor consisting of Dr Robert Willis and Dr Mac McKee as
project hydrologists, Gail Newton and Associates as project
botanists and Dr Kitchen as wildlife specialist.

This Enhancement Plan involved a process beginning with
identification of preliminary project goals by the Coastal
Conservancy. Based on this initial direction, a site analysis
was conducted to identify opportunities for enhancement
planning. Information compiled in this report was gathered from
September, 1986 through February, 1987. Further definition of
goals and objectives were influenced by opportunities and
constraints inherent to site conditions. Discussions with the
City of Eureka and the Coastal Conservancy led to a definition of
goals and objectives which are listed in Section 4.2 of the
Enhancement Plan.

This Enhancement Plan, after the City's approval, will be sub-
mitted and reviewed by both permitting and reviewing agencies
(California Coastal Conservancy, Humboldt Bay Harbor District,
California Coastal Commission, Army Corps of Engineers,
California Department of Fish and Game). The review and
permitting sequence offers several opportunities for public
review and hearings.

The City is currently establishing a non-profit organization that
would manage the Palco Marsh project, as well as other enhance-
ment projects planned in the City of Eureka. If the City is
unable to establish a nonprofit organization to perform this
function, then the Department of Fish and Game has expressed an
interest in managing the project area.

2.2 Site Definition

The Palco Marsh project site is located on the eastern shoreline
of Humboldt Bay at the western edge of the City of Eureka. It is
surrounded by urban development on three sides: 1) Del Ncrte and
Hawthorne Streets and adjacent commercial/industrial uses to the

2-3

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north; 2) Broadway Avenue with commercial uses to the east; and
3) the newly constructed Bayshore Mall to the south. West of the
Palco Marsh project site are Humboldt Bay mudflats, central
channel and the Samoa Peninsula. The Crown Simpson pulp mill is
located directly across the Bay channel on the Samoa Peninsula,
1/2 mile west of the Palco Marsh site.

The project is bisected by the Northwestern Pacific Rai;71road
right-of-way, which traverses north-soutb across the project
site. The east half of the project site consists of approxi-
mately 45 acres which includes a six acre developed area and a
39 acre marsh complex consisting of approximately 17 acres of
salt marsh, nine acres of brackish marsh, eight acres of freshwater
marsh, and five acres of riparian habitat. The western half of the
project site, 41 acres, consists of tidal flats, shoreline strip
of salt marsh and a four acre upland peninsula located just south
of the end of Del Norte Street. See Figure 2 for location and
nomenclature used throughout the report.

2.3 Related Projects and Properties

Several other projects, not a part of the Palco Marsh project
site, are related to the project and addressed in other portions
of this report. These include: 1) "Parcel 4", a 15 acre parcel
zoned for Coastal Dependent Industrial Use which was acquired at
the same time as the Palco Marsh project site; 2) Maurer Marsh, a
10 acre freshwater marsh between Vigo and Mill Streets, is cur-
rently in private ownership. The City of Eureka with the Coastal
Conservancy is currently negotiating title to this wetland
portion of the parcel 3) a railroad spur and a 1/2 acre triangular
shaped "RR Marsh", which is currently owned by the Northwestern
Pacific Railroad but is being acquired by the City of Eureka,, arid
4) "Wetland Restoration Areas A and B", adjacent to the paved
drying shed area and belonging to General Growth Inc., are wetland
mitigation areas constructed as part of the Bayshore Mall project.

2-5

3.0 SITE CONDITIONS

3.1 Topc>graphy and Geology

The City of Eureka is situated on the edge of a gently sloping,
broadly rolling terrace that rises from 20 to 250 feet above the
central part of Humboldt Bay and surrounding tidal flats. Por-
tions of the City, including the project site, extend onto the
lowland areas that form the Bay margin (City of Eureka, Human
Safety Technical Background Study, 1977). According to mapping
of the California Department of Mines and Geology (1962), the
project site is underlain by recent alluvium. The upland terrace
area, east of Broadway, is underlain by the Pleistocene non-
marine sedimentary deposits of the Hookton Formation, made up of
loosely-aggregated gravel, sands and clay.

The project site, located on partially reclaimed tidelands and
estuarine deposits, is within a mile of the existing mouth of the
Elk River. The tendency of north coast estuary areas to undergo
changes in configuration with fluctuating current, runoff and
sediment deposition characteristics, suggests that sediments on
the site were influenced by such estuarine movements. Materials
underlying the project site could be expected to be bay
sediments, river alluvium and sand dune materials.

Topographic information was compiled for the project site from
various existing sources of information. Additional elevations
were obtained during the site analysis phase of the project. All
elevations throughout the report will be to City of Eureka's
datum. Mean lower low water equivalents will be given in paren-
thesis where noted.

The topography of the site gently slopes upward from 1.7 feet
(2.1 MLLW) at the tide gate structure to 10+ feet at Broadway.
The salt-brackish marsh complex is located between 5.1 feet (5.5
MLLW) and 6.1 feet (6.5 MLLW) elevation. The freshwater marsh
area is generally at 6.3 feet (6.7 MLLW) elevation. The filled
and paved upland area containing the drying sheds is generally
between 8.0 feet and 10.6 feet elevation.

Indications for Enhancement Planning

The location and influence of Humboldt Bay and the Elk River has
varied throughout the site's history causing site conditions to
be conducive to re-establishment of wetland habitats. The
majority of the site remains unfilled; portions are still
influenced by tidal input or from upland drainages. The-rela-
tively low gradient of the Marsh, sensitive to small changes in
water surface elevations, dictates that careful planning will be
necessary to maintain or enhance the site for a particular type
of wetland. Elevations present on-site are conducive to an
increased yet still muted tidal prism. Grading in some areas
will be necessary to provide channels to distribute tidal input
or provide adequate drainage.

3-1

3.2 Soils

Lowland areas around the Bay have been subject to extensive dis-
turbance since the settlement of the area in the 1850's, making
the nature of native materials underlying the filled and paved
areas of the site difficult to determine from surface evidence.
The 1854 U.S. Coast Survey of Humboldt Bay (Bache, 1854) indi-
cates that the site at that time encompassed higher areas of
sandy grasslands and lower marsh areas subject to tidal 7inun-
dation. Though unmapped, a correlation can be made with soils
found near the mouth of the Elk River. Soils in the Elk River
area are composed of two mapping units: Sand Dunes (SD) and
Bayside Silty Clay Loam (Ba6). The "Sand Dunes" classification
consists of wind-deposited, fine-grained sands. The Bayside
soils have high clay content and are derived from reclaimed tidal
marshes at elevations near sea level (McLaughlin and Harradine,
1965).

on-site soils data was analyzed by CalTrans during explorations
in connection with the proposed Eureka freeway in 1965 and 1971.
CalTrans' investigations include a series of b 'ore holes on a
north-south trending line through the site. These bore holes,
ranging in depth from 16 to 55 feet, penetrated extensive layers
of saturated sands, clays, organic and marine layers, tending to
confirm what is thought to be the original conditions on the site
(sand dune, river mouth and bay deposits). Very.wet soils (free
water present) conditions were encountered at or near ground
surface for the majority of the holes located on the site.

Surface soils in the Palco Marsh wetland area were analyzed for
texture, salinity and pH (see Table 1). These samples exhibited
a range of texture varying from clay to organic soils. Signs of
anaerobic decomposition and hypersaline conditions were found in
the clays associated with the unvegetated salt marsh areas, indi-
.cating poorly flushed tidal areas; thick organic layers were
found in the fresh/brackish marsh area.

Aerial photographs dating back to 1931 and historic maps were
examined to identify areas where fill in the paved drying shed
area may exist. It appears that higher upland areas were leveled
to fill lower tidal areas. Several exploratory holes, dug in
1986 with a backhoe, indicated that the paved area consists of an
average of four inches of paving. Sandy grassland soils, as well
as imported river run gravel, served as the source of fill.
Bayside silty clay loam was encountered two to three feet below
the surface in some locations. Groundwater was present
approximately five feet below the surface, which is consi stent
with adjacent wetland elevations (5.0 foot elevation).

3-2

TABLE 1

SOIL PH/SALINITIES

soil Elevation PH Salinity (ppt)

Bay - cordgrass n/a 6.6 15

Bay - pickleweed n/a 6.4 25

Marsh - pickleweed 6.0 6.4 15

N. Marsh - mudflat 5.3 6.7 60

N. Marsh - mudflat 5.3 6.9 50

Saltgrass - rear 5.3 6.5 30
inlet

Northend - pickleweed 5.5 5.8 25

Southend - pickleweed 6.1 6.8 25

Historic slough 5.0 6.5 65

Brackish marsh 5.7 5.0 5

Freshwater marsh 4.6 4.7 0

3-3

indications for Enhancement Planning

Soils in the existing wetland areas exhibit characteristics that
would normally be expected, given the present hydrologic
influences and vegetative cover. Surface soils in the salt marsh
area could be improved with an increase in tidal flushing, there-
by reducing salinities and providing suitable conditions for
natural revegetation by existing salt marsh species. Rdmoval of
the paving, and a minimal amount of fill in the area surrounding
the drying sheds, would provide habitat for willows and alders,
if planted. Other upland species would also expect to colonize
in the area. Removal of all the fill, as well as 2-3 feet of
native soil would be necessary to subject the area to enough
tidal action to establish salt marsh habitat. Freshwater ponds
could also be established in this area provided an adequate
source of water is available.

3.3 Hydrology

The Palco, Marsh project site is physically separated from
Humboldt Bay hydraulics by the existing Northwestern Pacific
Railroad right-of-way and the City of Eureka's maintenence dike.
The principal hydrologic inputs to the Palco Marsh include tidal
influx, urban runoff from areas east of the site, direct preci-
pitation and ground water discharge.

3.31 Tidal Influence/Surface Runoff

A tidegate, located on the bay-side of the railroad right-of-way,
has historically limited tidal influence into the Marsh. The
existence of established salt marsh vegetation in the Marsh indi-
cates that the tidegate has not been kept in proper working
order. At present, sediment and debris are keeping the tidegate
partially open. A 24 inch culvert extends from the tidegate to
the inland side of the railroad tracks. From this point, tide
waters empty into a 10 x 20 foot "pool" (see Figure 3). The
Palco Marsh drains into this pool and receives tidewaters, via
two 12-inch PVC pipes located on the City of Eureka's maintenence
dike. Tides in excess of 4.0 feet enter the pool area and fill
the lateral ditches. Only tides in excess of 5.4 feet enter the
Palco Marsh, and only for a brief period of time.

..During summer months, tidal influence on Palco Marsh is limited.
Water surface elevation changes of 0.2 feet were measured during
a tidal range that varied eight feet. This represents an extremely
muted tidal cycle. This combined with evapotranspiration results
in hypersaline conditions, soil shrinkage/subsidence and algal
mats. During winter months, tidal influence is similarly limited
but influence of surface runoff, as a result of precipitation,
causes more dramatic changes in water elevations. Observations
indicate that a one inch rainfall caused water levels in the
marsh to increase as much as six inches and took several days to
drain out. (see Figure 5).

3-4

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36" Sewer Line
36"Sewer Line

18" Sewer Line.
_0 0
I.G. 00
b CD 0- <
M
>
r- FO

rn
12"Water Line
x 12"Water Line
> Top of Bank ......
ine,-,

z A'
G)
m
0 do

The area of the Palco Marsh is approximately thirty-nine acres.
Hydrologic systems in the vicinity of the Palco Marsh include 13
watershed areas (see Figure 4). Of these thirteen areas, only
input from Drainage Areas 2 through 9 (a total of 197.5 acres)
drain into the Palco Marsh. Of the total 197.5 acres, drainage
from approximately 150 of the acres flow into the Maurer Marsh
(Drainage Area 7) and subsequently into Palco Marsh.

Drainage Areas 10 through 13, though adjacent to the project,
drain into Humboldt Bay without entering the Palco Marsh.
Drainage area acreage, elevations and relevant drainage
structures are listed in Table 2 for each of the watershed areas
depicted in Figure 4.

Groundwater data for the project site are limited. CalTrans test
borings near South Broadway have indicated shallow (unconfined)
groundwater resources in the east portion of Palco Marsh at
approximately 5.0 feet elevation. Backhoe pits, dug in the
drying'shed vicinity also indicated similar groundwater levels.
Springs also occur at the base of the bluff-east of Broadway,
adjacent to the Palco Marsh. The marsh vegetation in the eastern
portion of Palco Marsh consists primarily of freshwa 'ter species
supported from these high groundwater sources. The magnitude and
temporal variation in the groundwater discharge occurring at the
project site remains unknown.

3.32 Flooding

The existence and severity of flood hazards in the City of Eureka
were investigated by the Federal Emergency Management Agency
(FEMA). The study covered all significant flooding sources
affecting Eureka. As the Management Agency concluded:

"Eureka is protected by the Samoa Peninsula from flooding by
the open ocean; however, areas of Eureka adjacent to
Humboldt Bay are subject to tidal flooding. The highest
estimated tidal elevation recorded at Eureka occurred on
February 4, 1958. The estimated storm surge height was
approximately ... 10 feet above mean lower low water. (MLLW)"

This elevation was determined in the FEMA study to represent the
100-year storm tide elevation. Flood-prone areas, as mapped by
FEMA, lie immediately west of the Northwestern Pacific Railroad
right-of-way. Within the project site, only the Del Norte Street
pier and adjacent peninsula, and the shoreline strip of salt
marsh are mapped as being in the 100-year flood zone.

Although the Palco Marsh does not appear to be directly affected
by storm surges, a mathematical model was developed to determine
the probable variations in marsh water levels resulting from
extreme hydrologic and tidal events. A combination of a 10 foot
storm tide and a 100-year precipitation event (3.0 inches of
rain) resulted in a water level in the marsh of 7.5 feet. This
would indicate the highest water surface elevations expected in

3-6

m: m:
t
tA

:7.7.

m-w

jj
4*P

gJ
Mx,
.. ... .. ...

XY.,
!14W44.X

.... ........
. . ..... ....

a ::::.j

WATERSHED AREAS

3-7 Figure 4

TABLE 2

PALCO MARSH DRAINAGE AREAS

Area of
Drainage Drainage Flow
Area (acres) into Via Elevation* Notes

38.74 pool 2-12" culverts 5.1 Palco Marsh Area

pool - Bay 24" culvert 3.7 Flow to Bay

2 3.7 1 18" culvert 6.4 Pocket Marsh #7

3 6.6 1 1-18" culvert 6.2 runoff drainage
2-8 " culverts from City Garbage

4 3.4 1 surface runoff Harbor Lanes
Bowling Alley

5 10.4 1 30" culvert enters marsh
�10.0 adjacent to
bowling lanes

6 4.4 1 surface runoff urbanized area
north of Vigo

7 19.0 1 20" culvert Maurer Marsh
3.6 (10.5 acres) +
urbanized area

8 150.0 7 36" culvert Henderson Street
11.2 drainage

9 6.0 Pool surface runoff asphalt/drying
- shed area

10 7.0 Bay 25" culvert Bayshore Restora-
6.7 tion Area A

11 7.2 9 adjustable weir Bayshore Restora-
�7.0 tion Area B

12 26.4 11 2-18' culverts drainage from
11.4 Har ris St. south

13 15.2 9, 11 direct surface north parking
runoff - area of Bayshore
Mall (partial)

City of Eureka Datum

3-8

the marsh from this single storm event.

On February 18, 1986, (after a sequence of high rainfall, com-
bined with a sequence of high tides reaching up to 6.5 MLLW),
water 'levels in the marsh were above what was produced by the
mathematical model. These elevations, from observation, were
estimated to be approximately one foot below the street surface
at Hawthorne and Felt Streets, making the water surface- elevation
approximately nine feet. A simulated storm event, representing
conditions prior to February 18, 1986, was placed into the hy-
draulic model; results approximated field observations. Approxi-
mately six inches of rain fell in a seven day period. Although
none of the individual storms were of a significant nature, the
cumulative effect on the Palco Marsh was significant. High
tides, as well as constricted outflow, severely limited discharge
of fresh water from the marsh. Fluctuation in water levels
occurring in the marsh, caused by tidal influence and storm
events are depicted in Figure 5.

3.33 Water Quality

Water quality data have been compiled which attest to the extreme
variability in water quality factors in Humboldt Bay. Nutrient
levels, salinity, temperature, and dissolved oxygen levels vary
with periods of ocean upswelling, tidal changes'l seasonal temper-
atures and storm runoff. The Humboldt Bay Wetlands Review and
Analysis (Shapiro, 1980) discusses these general relationships
and their significance in more detail.

Land use factors which affect water quality in Humboldt Bay and
associated tidal marshlands include-discharge from the Arcata and
Eureka sewage treatment plants, agricultural, silvicultural and
urban runoff. Restrictions on the harvest of shellfish from the
Bay result from bacterial contamination from agricultural, sewage
collection and treatment facility sources. Suspended sediment
deposition and turbidity in the Bay results primarily from influx
of turbid ocean water into the Bay, as well as erosion and
sediment transport from upland watersheds.

The Palco Marsh is primarily influenced by both surface runoff
from urban areas and tidal influx. Runoff from urban areas may
contain toxic chemicals and sediment contributed by residential
and commercial areas. On-site wetland areas are influenced by
bay salinity to varying degrees as indicated by the distribution
of marsh vegetation described in Section 3.4. Although salini-
ties generally decline with distance from bay discharge outlets,
localized areas subject to limited inundation, poor drainage and
flushing, combined with seasonal evapotranspiration, tend to have
higher salinities than bay waters.

Six basic water quality parameters were measured during this
study: temperature, pH, dissolved oxygen (DO), salinity, bio-
logical oxygen demand (BOD) and suspended materials.
These water quality parameters are summarized in Table 3.

3-9

PRESENT CONDITIONS IN MARSH
WITH VARIOUS PRECIPITATION EVENTS

< .......
'00 YEAR
-------------
7 ------
1-0 Y LE

ul 2- YEAR

ILL

4- . ................

20 40 60 80 100

TIME IN HOURS

WATER LEVELS IN MARSH
PRESENT CONDITIONS

3-10 Figure 5

TABLE 3

WATER QUALITY

Sample Temp. Salinity Suspended BOD
Location 0C pH DO Ppt Material mg/1 mg/l

I Bay 15.5 5.7 5.6 90 .007 31.6

2 Inlet 16.0 5.9 4.0 55 .008 30.0

3 500' E. 17.5 6.0 2.7 40 .104 50.7
of Inlet

4 500' E. 17.0 6o2 6.5 60 .003 40.5
100' N.
of Inlet

5 Middle of 18.5 6.1 2.4 110
.015 40.0
N. Marsh

6 Fresh Water 15.0 5.8 4.0 1 .028 44.6
Marsh

7 Middle of 18.0 6.3 5.5 2.5 .003 29.5
S. Marsh

8 Maurer Marsh 18.0 4.0 3.7 2.5 .001 30.0
Drainage

3-11

The results indicate some of the important processes occurring in
the marsh. As would be expected, water temperatures increased
relative to distance from the bay inlet. An exception to this
was the sample taken within the freshwater marsh area. Lower
temperatures would indicate the presence of surface groundwater
flow. High temperatures and salinity toward the north end of the
Palco March indicate hypersaline conditions due to poor circula-
tion and excessive evapotranspiration. Areas subject to poor
circulation had a high BOD value indicating a lack of oxygen.
High suspended solids values were found in vegetated areas where
organic decomposition was occurring.

Indications for Enhancement Planning

One of the facotrs that limit enhancement opportunities is the
high elevation (4.1 MLLW) of the culvert underneath the railroad
tracks which brings tidal waters from the bay to the marsh.
Though it would be possible to install a new culvert at a lower
elevation under the railroad tracks, this alternative is not
feasible for two reasons. First an 800 foot channel would have
to be dredged from the main bay channel to the culvert. Second,
since the Palco Marsh is, for the most part well above 4.0 MLLW,
major grading and drainage reconfiguration would be necessary to
take advantage of the extra tidal variation. This would require
excessive costs and environmental degradation beyond what was
intended in the original project goals.

Increasing tidal circulation into the marsh can be accomplished
by removing existing constraints, including removing the tidegate
and modifying the area where marsh runoff and tidal influx inter-
change. Results from the mathematical model indicated that
either enlarging and/or lowering the elevation of the exchange
pipes under the maintenance dike, removing the tidegate, or modi-
fying channel configuration, would not, in themselves, signifi-
cantly change the conditions in the marsh. A combination of all
the above would be necessary to effect such a change.

Surface runoff from the surrounding watershed areas dramatically
changes the hydraulics of the Palco Marsh during the rainy
season. The majority of surface runoff entering the Palco Marsh
is contributed by runoff from 150 acres that enters via the
Maurer Marsh. During storm conditions, not only does water back
up into Maurer Marsh due to higher water elevations in the Palco
Marsh, but outflow is restricted from vegetation surrounding the
connecting culvert under Vigo Street.

Flooding problems in the Palco Marsh are a result of constric-
tions on freshwater discharge from the marsh, rather than tidal
influx. Increasing the rate of run-off leaving the Marsh,-with-
out appreciably increasing the volume of tide waters entering the
marsh, would reduce flooding problems. Modeling results indicate
that increasing the capacity of the exchange area (Figure 3) will
improve tidal exchange and drainage without significantly increa-
sing the intake volume of tide waters during flood conditions.
This is due mainly to the short period of tidal peaks, restricted
inflow through the culvert under the tracks and the relatively
high elevations of the marsh.

3-12

3.4 Vegetation

3.41 Overview

Wetlands around Humboldt Bay.can be categorized into salt marsh,
brackish marsh, freshwater marsh, riparian and swamp habitats.
These classifications occur around the Bay in varying degrees of
distinction and health.

In general, the vegetation of the site is typical of marshlands
around Humboldt Bay (Koplin, et. al. 1984; Newton 1984, 1985a,
1985b; Seeman 1985, 1986). The salt marshes west of the
railroad tracks are healthy and diverse. The salt marshes east
of the railroad tracks are degraded and low in plant diversity.
Extensive riparian woodlands with diverse understories and fresh-
water marshes are located on higher elevations toward the east
side of the marsh complex. Between the riparian woodlands and
the salt marshes, a large zone of freshwater brackish marshes
occurs. The assortment of brackish marsh vegetation is unique in
that most types of brackish marsh located around Humboldt Bay can
be found within this one marsh complex. This 'is due in part to
the gradual elevation increase and the inland extent of the
wetland. As a result, the gradient changes from salt to brackish
to freshwater marsh.

The vegetation of the Palco Marsh complex was sampled late in the
flowering season, between September 29 and October 15, 1986. Due
to the timing of this study, species composition, quantitative
variations, and strata height are biased toward the late blooming
species and/or those species that are distinguishable at that
time of year. A compiled species list can be found in Appendix
B. This species list is representative of the season of this
study.

The vegetation patterns of the site were mapped in detail,
especially the vegetation of the salt marshes located east of the
railroad tracks. Location and extent of the rare species
Humboldt Bay gumplant was mapped along with the location of
invasive exotic species. Figures 6 and 7 depict the location of
rare species and invasive species, located on the site,
respectively.

The Vegetation Descriptions (Section 3.42) describes the general
factors influencing the current vegetation of the Palco Marsh.
Each specific vegetation type is described in detail in Appendix
B; codes used correspond to the 1" = 1001 vegetation map which
accompanies this study.

The site contains a large population of the rare plant species
Humboldt Bay gumplant. Any activity necessary to increase the
diversity of the salt marshes will not adversely affect this
population of the rare gumplant. These plants, for the most
part, occur at high elevations along the west side of the rail-
road right-of-way. only one specimen was found in the Marsh
complex.

3-13

There are four other species of concern that were found on the
site. The berms surrounding the marshes contain three invasive
exotic species, scotch broom, french broom, and pampas grass. In
addition, an invasive plant, the common reed, native to Cali-
fornia but uncommon around Humboldt Bay, is also found on the site.

3.42 Vegetative Descriptions

The vegetation of the site is briefly descri bed in the following
discussion. The complete description of each vegetation type (or
plant assemblage), based on species composition, quantitative
variations, and structure, has been placed in Appendix B.

3.421 Salt Marsh -- SK

The salt marshes on the site are located both in a shoreline
strip west of the railroad tracks and in Palco Marsh, east of the
tracks. The salt marshes west of the tracks contain the usual
diversity of vascular plants typical of salt marshes around
Humboldt Bay. Jn this narrow strip of marsh, the three dominant
salt marsh species, pickleweed ('Salicornia virginica),.cordgrass
(Spartina densiflora), and salt grass (Distichlis spicata) occur
together in varying amounts., Occasional throughout these marshes
are sea lavender (Limonium californicum var. californicum),
jaume,a (Jaumea carnosa), and arrow grass (Triglochin spp.). The
rare Humboldt Bay gumplant (Grindelia stricta ssp. blakei) is
found along the upper edges of this marsh and the salt marsh
snail (Ovatella myosotis) is common in this location.

The salt marshes and extensive mud flats east of the tracks are
degraded and lack much of the diversity common in healthy salt
marshes on Humboldt Bay. With the exception of the three main
salt marsh species -- pickleweed, cordgrass, and salt grass --
none of the other salt marsh species occur in this area. The
only location that contains a gumplant and a modest population of
jaumea is a small portion of pickleweed marsh adjacent to the
inlet channel.

Orache (Atriplex patula) and brass buttons (Cotula coronopifolia)
are common in many of the areas east of the tracks, becoming
dominant in small areas away from the inlet channel. These
species are typically found in areas that are disturbed or
severely stressed, likely from oxygen starvation and hyper-
salinity due to evaporation during the summer months.

Several areas east of the tracks are dying back at an accelerated
rate. Aerial photos show that the majority of the die-back has
occurred since 1981, with significant differences between 1983
and 1986. Tufts of salt grass from which the substrate has been
eroded still persist in this area.

3-14

Since the health of the existing salt marsh east of the tracks is
one of the main concerns of the enhancement project, the vegeta-
tion was mapped in detail. Other marshes on Humboldt Bay located
at similar elevations are usually dominated by pickleweed and
Jaumea. More detailed vegetation descriptions and codes relate
to the vegetation map of the site are listed in Appendix B.

3.422 Brackish Marshes -- BM

Brackish marshes form at the interface between the salt marshes
and the freshwater marshes, therefore exhibiting a wide range of
salinities that change seasonally. The species composition
slowly changes as one moves from the areas near the salt marshes
to the areas near the willow swamps or riparian woodlands. Three
species of plants which are common throughout these brackish
marshes are salt rush (Juncus lesueurii var. lesueurii, pacific
silverweed (Potentilla iigedii ssp. grandis), and water parsley
(Oenanthe sarmentosa).

In general, the brackish marshes found on the.site are typical of
other such marshes around Humboldt Bay. Two types of marshes
located on the site that are uncommon around Humboldt Bay are the
pacific rush (Juncus effusus var. pacificus) and the common reed
(Phragmites communis var. berlandieri) stands. -,The pacific rush
marsh represents a unique resource;%the common-reed marsh could
represent a threat to Humboldt Bay marshes. Though none of the
brackish marshes, or species therein, are rare, the uniqueness of
this site lies in the quantity and diversity of the marshes
represented. Within the project site, most of the common types
of brackish marshes can be found.

The brackish marshes on the site are separated by species compo-
sition and structure. The brackish marshes vary from very short
areas dominated by grass species to the tall stands of slough
sedge (Carex obnupta).

3.423 Freshwater Marshes -- FM

The marshes included in this section range from the upper edge of
the brackish marshes to the riparian habitats (or willow swamps).
The freshwater marshes include two tall, emergent dominated
marshes and one emergent/floating-leaved marsh. These marshes
are typical of Humboldt Bay. Some have previously been described
by Monroe (1973), Newton (in Koplin, et. al. 1984), and Newton
(1984, 1985a, 1985b).

These freshwater marshes are extensive within the site and inter-
grade heavily with adjacent riparian areas. Similar freshwater
marshes can be found around Humboldt Bay but are usually in
grazed pastureland areas.

3-15

3.424 Riparian Woodlands (or Willow Swamps) -- R

The riparian woodlands are present in abundance around the east
edges of the site. Two riparian vegetation types are delineated
based on the herbaceous layer; one contains typical freshwater
marsh*species in the understory while the other contains dense
blackberry hedges and various grass species in the understory.

3.43 Rare Species

The three rare salt marsh species, which commonly occur around
Humboldt Bay, are Point Reyes' bird's beak (Cordylanthus
maritimu sp. palustris), Humboldt Bay owl's clover (Orthocarpus
castille-loides var. humboldtiensis), and Humboldt Bay gumplant
(Grindelia stricta ssp. blakei). of these species, only the
gumplant was found during the surveys conducted between September 29
and October 15. The bird's beak and the owl's clover are both
annual species and are not possible to locate at this time of
year.

The population of the gumplant is located almost solely along the
west side of the railroad berm and the adjoining are-as. (See
Figure 6). only one individual of gumplant was',located in the
marsh east of the railroad tracks. The total population on the
site is 4,061 individuals. The current degraded-condition of the
salt marsh east of the railroad tracks probably,could not support
either the owl's clover or the bird's beak. However, marginal
habitat for both species is located in the salt marsh west of the
railroad tracks. Enhancement activities should create habitat
acceptable for these two species within the Marsh, if they are
present near the site.

3.44 Invasive Exotica

The list of exotic species located on the site is extensive
(including plants such as the cordgrass, himalaya berry, and
brass buttons). Therefore, this discussion of exotics will be
limited to the highly invasive species worthy of eradication and
for which eradication is possible. Eradication of species such
as himalaya berry would prove costly and futile. The main exotic
species of concern located on the site are two species of broom
(Cytisus spp.) and pampas grass (Cortaderia selloana).

The locations of these species are indicated on Figure 7. The
majority of the pampas grass is distributed along the railroad
right-of-way and nearby berms. The species of broom are Imore
generally distributed throughout the site, but overall are less
abundant. Eradication of these species from Palco Marsh should
also include eradication from adjoining areas, particularly the
railroad right-of-way.

One other species of concern located on the site is common reed
(Phragmites communis var. belandieri). This species is cosmo-

3-16

cc:l@
480 1300
20 -- 550
0 3 05
3 1 300 200 3 2 1 1 25

Ma
I%j > LOCATION OF HUMBOLDT BAY GUMPLANT ON PALCO MARSH

Marks location of Humboldt Bay gumplant
(Grindelia strictd ssp. blakei)

Numbers refer to number of individual plants
M
(D o
rn
CY) U)

fC
CO

W
f 0

NCO

-k 41

I A I V L S I I C 1 0 N P A L C 0 M A R I
rn

a iTi I)a s (4 s C o r ta d e a s e oa n a
cotch broom @n'd French br-noll) Yt@-stls @op.
rn C nm m o n r e -J h ra c o m mi u n s v a r -b e T, I a n d e r i
in t p

rr)
(n

politan in distribution (Mason 1957); however, its occurrence
around Humboldt Bay is very limited. On the east coast and
throughout the interior of California, common reed occurs in
monotypic stands covering large acreages. The structure of those
-marshes decreases overall diversity and decreases wildlife
habitat values. For this reason common reed should be treated as
an invasive exotic in the Humboldt Bay area and should be eradi-
cated before it spreads throughout the Bay's marsblands-.

3.45 Influencing Factors

Three main factors influence the vegetation of a wetland: the
duration of inundation, the chemistry of the water, and the site
history. More specifically, the duration of inundation refers to
@oth inundation by tidal action and nundation by direct or
indirect precipitation. The most important aspect of the
chemistry is the relative amount of soluble ions in the water.
The third factor is the history of the site, particularly the
disturbance history. The 1854 map of the site shows tidal
marshes on the western edge of the site with small sandy areas
included. The eastern portion of the site at that time is shown
as vegetated dunes or grasslands with the very eastern edge
containing some brush. In 1931 the site east of the railroad
tracks was under agricultural use. The primary slough patterns
within the pasturelands follow the same route today as they did
in 1931. The riparian area near Highway 101 was much less
extensive than present day.

It appears that by 1939, the eastern portion of the present day
brackish marshes was no longer being as heavily plowed, as
evidenced by the tufts of vegetation. By 1954 the taller vege-
tation had spread throughout the eastern portion of the marsh and
the freshwater pond (of which a small remnant remains today) had
started to develop. By 1962 the pond was fully developed, and
the salt marshes were present. By 1972, the marshes appeared
well established, and the riparian area was slowly expandinq.

One of the more significant events in the vegetation history of
Palco Marsh occurred during'1981, during the construction of the
sewer line. The salt marshes located adjacent to Del Norte
Street and north of the inlet channel began dying back at a
rapid rate. The difference between the extent of the marsh
vegetation between 1983 and 1986 is dramatic, some areas having
diminished by 50% or more. Evidence of the erosion is present in
the vegetation on the site; isolated1tufts of salt grass can be
found on the mudflats.

With all three factors; water, chemistry and history varying
independently throughout a site, an association of plants is not
an adequate indicator of the environmental conditions that pre-
vail, since each species has different tolerances and can grow
under different conditions. Absolute lines between salt marsh,
brackish marsh, and freshwater marsh cannot be designated.

3-19

Indications for Enhancement Planning

Site conditions, as discussed in the preceding sections, have
not dramatically changed in regards to topography, soils or
off-site hydrology. Vegetation is more sensitive to changing
environmental conditions, and thus reacts more quickly to
changes. Because of this, opportunities are available to improve
the vegetation and consequently wildlife habitat valuesz There
are certain factors causing the marshes to be under stress and
affecting the marsh vegetation density. These include poor tidal
circulation and retention of storm run-off, which causes
hypersalinity and dissolved oxygen depletion. The unhealthy
condition of the salt marsh is evident by the lack of diversity
of the vegetation. Under an improved tidal regime, salt marsh
areas could be returned to a higher functioning value.
Information gathered at the drying shed area indicates that,
depending on the amount of fill removed and the availability of
future water sources, this area could support wetland vegetation.

The rare species of plants thrive better in healthy salt marshes.
Anything done to improve the circulation in the salt marsh would
enhance the area for rare plant establishment. Longterm Protec-
tion and stabilization of the marsh environment would also
encourage expansion of rare species habitat. (Newton,86)

Freshwater marsh areas are slowly succeeding towards replacement
by other-vegetation development. Large expanses of cattail have
filled in open water areas and the riparian edge is advancing
westward towards the freshwater marsh habitat. Deep, open water
pools that once support emergent species of plants, are now
limited to the one small open water area.

The four exotic species of plants mentioned earlier are prolific
propagators and difficult to control. For the most part Pampas
grass is limited to the upland areas outside and along the upper
edge of the Marsh. Reduction and eventual eradication of this
species will require both removing specimens from adjacent
property, particularly the railroad right-of-way, and adherence
to a regular yearly eradication program. The two species of
broom will require select removal. It is best to do this early
into the flowering period when it is highly visible and before
seed production begins.

The common reed pres ents a different problem in that this species
of plant is located in the brackish marsh areas and propagates
both from seed and rhizomes. Efforts to remove plants which cause
them to break apart and disperse by the tide or wind will only
aggravate the problem and could cause spreading to other parts of
the Marsh. As of yet, no known attempts to remove this plant
species have been made on Humboldt Bay.

Presently, areas containing common reed are accessible by backhoe
and or hand removal.

3-20

3.5 Wildlife

3.51 Overview

Humboldt Bay is second only to San Francisco Bay area in wildlife
species diversity and abundance in California. The Bay and asso-
ciated wetland habitats form an important link in the chain of
coastal wetlands extending from the Arctic Circle to South
America. The Bay itself provides a variety of estuarine environ-
ments which are supplemented and enhanced by the presence of a
variety of upland, riparian and freshwater marsh habitats.

Both salt and freshwater marshes have a high nutrient production
rate, which significantly contributes to the food base of aquatic
organisms. Because of the decline of wetland areas throughout
the State, wildlife species adapted for utilizing wetland areas
are increasingly dependent on the limited areas still remaining.
The value of both salt and freshwater marshes are significantly
increased when the two habitats are contiguous.

Wildlife use of the Marsh was analyzed during November, 1986.
In addition, census information developed during the Bayshore
Mall EIR (EDAW, 1984) and other research projects (Gerstenberg,
1972) was reviewed.

The Palco Marsh can be divided into three separate areas with
regard to wildlife use: 1)salt/brackish marsh; 2) freshwater
marsh; and 3) riparian areas. None of these areas are receiving
the amount of use by wildlife that would be expected given the
proximity of the Palco Marsh to Humboldt Bay, the known diversity
of wildlife in the area, and the lack of these habitats, in
general, in the greater Humboldt Bay Region. At present the area
with the richest wildlife fauna is the salt/brackish marsh.

3.52 Salt/Brackish Marsh Area

The salt marsh area presently has the most open water of all
three types of marsh and, therefore, receives the heaviest use by
birds; including a variety of shorebirds, herons, egrets, gulls
and waterfowl (see Table 4). In 1985, black-necked stilts bred
in the area and the young were successfully raised. In the
Falls of 1983-1986, migrating ruffs were observed to use this
area for feeding and resting. These two species, while generally
abundant in other areas, are rare in coastal areas such as
Humboldt Bay and represent unique sightings.

Throughout the year the principal use of the salt marsh by birds
is for feeding and resting. While use of the salt marsh is
greater than the other marsh areas, it is still below what would
be expected both in terms of numbers of species and numbers of
individuals. For example, this area historically had an
abundance of green-winged teal that could be observed feeding in
the area. Presently this species is seldom present and, when it
is, it is represented by only one to four individuals rather than

3-21

TABLE 4

AVIAN SPECIES LIST

ACTIVITY
SPECIES TOTAL AVERAGE FEED REST FLIGHT

SALT/BRACKISH WILDLIFE
Large Gulls 139 27.8 4 69 27
Bonapartes Gulls 17 3.4 100
Killdeer 18 3.6 10 85 5
Greater Yellowlegs 40 8.0 80 15 5
Small Sandpipers 72 14.4 72 10 18
Dowitchers 105 21.0 66 22 12
Great Blue Heron 15 3.0 9 73 18
Snowy Egret 21 4.2 74 11 14
Black-Crowned
Night Heron 61 12.2 100
Common Egret 14 2.8 53 38 19
Shoveler 34 6.8 63 26 11
Green-Winged Teal 243 48.6 100
Black Shoulder Kite 5 1.0 100
Cooper's Hawk 3 .6 100
Black Phoebe 9 1.8 15 85
Marsh Wren .33 6.6 45 35 20
Song Sparrow 7 1.4 35 65
Raven 5 1.0 5 95
TOTAL - Salt/Brackish 685 137.0

FRESHWATER KARSH
Redtailed Hawk, imm 5 1.6 100
Kestrel-Male 2 .6 30 50 20
Marsh Wren 66 22.0 45 35 20
Snipe 3 1.0 100
Common Egret 35 7.0 100
Great Blue Herron 3 .6 100
TOTAL - Freshwater 114 25.3

RIPARIAN
Song Sparrow 22 4.4 52 10 48
Fox Sparrow 29 5.8 18 11 71
Chestnut-Backed
Chickadee 64 12.8 43 8 49
Black Phoebe 10 2.0 73* 27 73*
Yellow-Rumped Warbler 40 8.0 19 14 67
Junco 52 10.4 100
Towndsen's Warbler 7 1.4 26 14 60
Red-Shouldered Hawk 3 .6 88 12
Cooper's Hawk 2 .4 100
TOTAL - Riparian 229 25.4

From 5-day Survey (November 04 - November 18, 1986)

020:Table 4 3-22

TABLE 5

KAMMALS (EXPECTED)

NAME HABITAT

Western harvest mouse throughout
California mouse throughout
California vole throughout
Norway rat throughout
Black rat throughout
House mouse edges

marsh shrew marsh,field
Shrew mole field edge

Brush rabbit marsh edge

Gray fox edges
Common dog throughout
Raccoon edges
Long-tailed weasel edges
Stripped skunk woods

California myotis woods
Red bat woods
Big brown bat woods

Black-tailed deer edges

3-23

the dozens seen in the past. This suggests that changes have
occurred that have reduced the available food for green-winged
teal. Snowy egrets feed in the area regularly, but common egrets
and great blue herons rarely do more than rest. Usually, these
last two species would forage heavily in a habitat such as this
if the proper food items were present.

Humboldt Bay is known to be an important link in Spring@and Fall
MigrationS of Shorebird5; past studies indicate that the
Palco Marsh site was extensively used by shorebirds. Long-billed
dowitchers, greater yellowlegs and willets are @!urrently the most
common large shorebirds observed feeding in the open water areas
of the salt marsh. Though an assortment of smaller sandpipers
were using the open mudflat areas, their numbers were much less
than normally would be expected to be feeding in the area. Also
missing were large numbers of marbled godwits and phalaropes
which would normally be present. This recent decrease in use by
shorebirds can be considered significant.

Even though no direct sampling of the food base was conducted
during this study, observations indicate a lack of necessary food
items. Mudflat invertebrate fauna, normally present in a salt
marsh area, is lacking in the Palco Marsh. Marine infauna were
only found near the inlet channel and the salt marsh snail,
normally common in salt marsh areas, was absent from the Palco
Marsh site. Aquatic insect larvae was most likely the main food
item being utilized.

Gulls of various species are quite common on this salt marsh and
spend a great deal of time resting in the shallow water areas.
Their abundance is due largely to the adjacent City Garbage
Company of Eureka transfer station. However, Bonaparte's gulls
use the area and feed in the marsh itself and Sabine's gulls have
been observed in the area during migration. In particular, the
Sabinets gull has been seen there during severe storms at sea and
has appeared to seek refuge in the area. Use of the area by the
more common gull species (California gull, ring-billed gull,
herring gull and Western gull) will remain heavy as long as the
transfer facility is in the area.

The group of birds most conspicuously absent is the waterfowl.
The only species observed regularly in the salt marsh were a few
green-winged teal, shovelers and pintails. There are about a
dozen species of ducks alone (eg. mallard, gadwall, etc.) that
one would expect to see in the salt marshes around Humboldt Bay,
The reasons they are not present are not completely clear, but a
lack of suitable foods, poor water circulation, and lack--of any
deep water (six to nine foot depth) are the most likely
explanations.

The brackish marsh is immediately adjacent to the salt marsh and
has little open water at any time. This habitat is used almost
exclusively by both species of egrets, great-blue herons and
black-crowned night herons for roosting. Brackish marshes with
more open water are heavily used in other parts of Humboldt Bay

3-24

for foraging by these ardeids, by numerous species of shore birds
and large numbers of waterfowl. The lack of open water reduces
the available food and, therefore, the value of this area for
wildlife.

3.53 Freshwater/Riparian Marsh

The freshwater/riparian marsh area has virtually no open water
and almost no use by wetland-related species of birds (Table 4).
The primary wetland species present in the area is the marsh
wren. It's use of the area is year-round, with a significant
breeding population present in the summer. Some of the larger
waders (common egret and great-blue heron) use this area for
roosting and will forage on the rodents in the habitat. In
addition, redtailed hawks, cooper's hawks, kestrels and black-
shouldered kites make limited use of this area's rodents. Based
on observed captures, it would appear that the most common
species of rodent is the California vole.

3.54 Use of Palco Marsh 1?y Mammalian Species

No trapping studies were conducted in any of the three marsh
areas to determine population levels of rodents or other mammals.
Larger mammals' use of the area was primarily observed to occur
along the Bay's edge, as well as in the freshwater marsh area.
This area receives heavy use by gray foxes, raccoons and domestic
cats. Signs of occasional use by deer were also observed.
Mammals expected to be found in this area are listed in Table 5.

Indication for Enhancement Planning

The Palco Marsh has a great potential for wildlife use that is
currently not being observed in the area. The general location
next to the bay and adjacent wetlands, as well as the size and
variation of the marshes all contribute to the uniqueness of the
Palco Marsh. Since many of the wetland areas surrounding the Bay
are limited in their lateral extent they tend towards narrow
habitat ranges and often monotypic types of wetlands. Even
though the general distribution of marshes in Palco Marsh, from
salt marsh in the west to riparian habitat in the east, occurs in
a short distance, a unique balance exists. For the various
species of wildlife utilizing the area, the site offers resting
and feeding areas, nesting and freshwater sources, refuge from
storms and, presently, mudflats exposed even at high tides.

@t would be difficult to justify expansion of one type of habitat
in favor of another. Freshwater marshes are limited around
Humboldt Bay, and as seen at Arcata's freshwater marshes and
oxidation pond, are well used throughout the year. Though a case
could be made to expand the freshwater marsh area, adjacent
freshwater marsh areas (Maurer, Bayshore Mall Restoration Area 2)
offer ample opportunities for future increased use. The best use of

3-25

the site seems to be in maintaining a balance of the diverse
range of habitats present. Therefore, the best opportunities to
enhance the site lie in correcting the problems within the Marsh
..to provide higher quality habitat.

The major problem with the Palco Marsh with regard to wildlife
use is the lack of water circulation in the salt marsh and the
lack of significant amounts of open water habitat in the brackish
and freshwater marshes. This results in reduced food production
for all Species of water-related birds and in a lack of water
surface for landing and take-off for certain waterfowl species
(eg. ruddy ducks; greater scaup, coots, and grebes). The outcome
is both reduced numbers and diversity of wildlife at the Palco
Marsh.

Improving the circulation of tidewater throughout the saltmarsh
will improve its value to wildlife. The lack of circulation in
this area causes low food availability for wildlife. organisms
normally associated with salt marsh-related mudflats (and good
circulation) are absent in the Palco Marsh. These include inver-
tebrates which are critical for foraging by shorebirds, snowy
egrets, etc. An increase in tidal flows would allow the rede-
velopment of this invertebrate fauna; subsequently the diversity
and numbers of wildlife in the area should increase.

If a deep water pond (six to nine foot depth) was developed in
the freshwater/brackish marsh area, there would be an appreciable
increase in both diversity and numbers of wildlife using the
area. The important submerged aquatic plants necessary for the
development of a food base in the pond are present in the resi-
dual pond left in the freshwater marsh. This would allow water-
fowl, grebes, etc. to land, forage and have the safety of deeper
water for escape from potential predators. Herons and egrets
would have a foraging area on the edges of the pond and would
roost near this new feeding area. If more ponds were developed,
a breeding waterfowl population might occur in the area. Otters
commonly use the Bay adjacent to the Palco Marsh. If significant
areas of open water were developed in the various types of marsh
then it would be reasonable to expect otters to make occasional
use of the area. Other species of mammals would be unaffected by
alterations of the three habitat types present in the Palco
Marsh.

3.6 Mosquito Vectors

Though mosquito problems are generally not significant around
Humboldt Bay, sporadic outbursts, generally associated with tidal
pools, do occur. The most significant problem area on the Bay is
at the Palco Marsh site, where its location, upwind from a large
population center, amplifies the situation (Strickland, pers.
com.)

The County Public Health Department has been monitoring and
treating the Palco Marsh area for the past six years (from May to

3-26

September) to assure the minimization of mosquito production.
(Prior to this time the City,of Eureka managed this task.) The
primary problem species in this area is the mosquito, Aedes
dorsalis, a vicious biter of humans with the capacity '&f migra-
ting up to 20 miles from its breeding habitat (Strickland, pers.
com.). This is a brackish flood water mosquito which lays its
eggs on dry land subject to infrequent tidal inundation. The
best habitat would be shallow depressions that are filled at a
high high tide and left standing for ten days. This species of
mosquito hatches from May to September and is a prolific breeder.

The area which contains the type of habitat favored by this
mosquito is located in the southwest corner of the Palco Marsh,
just north of Vigo Street. Tidewaters enter the marsh and move
towards the south end of the marsh, flooding the area via several
ditches. Freshwater run-off from the Maurer Marsh, after cross-
ing under Vigo Street, drains towards the west and subsequently
into the southwest corner. This combination causes the necessary
breeding conditions.

Source reduction is the most successful mosquito abatement
method7 Either eliminating tidal influence into this area or
-improving tidal action (where standing brackish flood water would
not occur) would be the best control for this species. The Marsh
has been successfully treated regularly for the past two years
using a bacterial larvacide "BT Formulation" (Bacillus
thruingiensis var. israelensis). This is non-toxic to other
aquatic organisms, being specific for the destruction of mosquito
larvae. other methods such as lateral ditching have been used or
are available but have not been found to be cost-effective.

One suggestion made by the County Health Department was to provide
nest boxes that would attract violet-green swallows or other
insectivorous birds. If this proves to be a feasible alternative,
local service groups could be contacted to further assist in this
endeavor.

3-27

3.7 Land.Use/Access

3.71 Site History

Lowland areas around Humboldt Bay have been subject to extensive
disturbance since the settlement of the area in the 1850's. The
1854 U.S. Coastal and Geodesic Survey of Humboldt Bay (Bache,
1854) indicates that the site at that time encompassed areas of
sandy grasslands and lower marsh areas subject to tidal
inundation. At that time, existing settlements included
Bucksport to the south, and Fort Humboldt to the east (EDAW,
1984).

By 1870, some of the wetlands between "A" Street in Eureka and
Bucksport had been diked and reclaimed for agricultural pasture.
The dikes were improved and used in 1901 for the Northwestern
Pacific Railroad (EDAW, 1984); these diked areas included the
Palco marshes. The Palco marshes originally consisted of tidal
sloughs and salt marsh, but the placement of fill for the rail-
road right-of-way subsequently caused retention of runoff and the
subsequent development of fresh/brackish marsh complexes.

After diking, the Palco marsh area was used for pasture.
Remnants of fenceposts and lines are still evident in recent
aerial photos and site reconnaissance. This area was part of the
larger Russ Ranch, which was located on top of the bluff east of
Broadway Avenue. During this time, the Dolbeer'& Carson Lumber
Company was offloading logs from railcars into the Bay from a
wharf built for that purpose; remnants of this wharf can still be
seen in the Bay just west of the Palco marsh. Logs dumped at
this location were floated up to the mill near the Carson Mansion
site.

In the 1870's, the South Park Race Track was built in an area
near Broadway and Wabash. This site was used for both horses
and, later, automobiles. The area at the extreme northern end of
the Palco marsh was used for pasturing horses that raced at the
track. A boxcar, remnants of which can be seen today, was moved
on to the site to store hay. (Poyfaire, pers. comm.)

The Holmes-Eureka Mill was established in 1903 on "ten acres of
sand dunes" located south of the project site. The original
plant employed 40 workers. By the 1920's, Holmes-Eureka was a
"highly mechanized modern plant, covering 50 acres, employing
over 500 men, and engaging in the "world-wide export" of Humboldt
County redwood lumber. The plant was primarily located between
the Bay and the railroad right-of-way at the Parcel 4 location
and along the shoreline. Areas east of the railroad were used
for log and lumber storage (Sanborn Insurance Maps of Eureka,
1920; Steenfott Collection).

From 1930 to 1950, the Eureka Lumber and Crossarm Company built
cross arms for telephone poles and other uses on the site north-
west of Mill Street. The existing drying sheds in this area were
built in 1958 and 1959. The Pacific Lumber Company bought the

3-28

site in 1959 and used it more or less continuously until 1983,
for the drying and storage of lumber. During this period, the
site was substantially graded, creating a series of basins and
berms throughout portions of the property (LSA, 1986).

The Palco Marshes, though, remained unfilled. Comparison of
recent aerial photographs with his@@oric maps show that the
western portion of the marsh retained its topographic cliarac-
teristics (present over one hundred years ago), as evidenced by
the cut-off slough and associated drainages. (See Figure 8).
Since at least the beginning of this century, with the diking for
agricultural use and placement of the railroad right-of-way, the
Palco Marsh has been influenced by retention of some upland run-
off and limited saltwater intrusion from the Bay.

In the early fifties, Hawthorne Street, off Broadway, ended
approximately where the current City Garbage Company of Eureka
office is now located. A house was located there, and the owner
raised and sold chickens. Mr. Tom Hall, involved in construction
and demolition of bridges and buildings, improved the road
(filled the marsh) to where Hawthorne Street turns into Felt
Street. Here, a circular road was constructed for storage of old
trusses and timbers from Hall's construction business. This area
was bermed and buffered from the marsh as part of conditions for
City Garbage Company's Coastal Development Permit in 1978.
(Poyfaire, pers. comm.) Drainage from City Garbage is filtered
through sand prior to entering the marsh. (Linda Locklin;
Coastal Commission, pers. comm.)

In the 1940's, a twelve inch water main was installed just east
of the railroad tracks. This new line, enclosed in a raised
berm, runs along the western edge of the Palco Marsh from Del
Norte Street to Vigo Street, before turning west towards the
track. This fill and drainage alteration subsequently minimized
tidal influence and altered the vegetation in the marsh.

In 1981, both a 18" and a 36" sewer main was installed adjacent
to the water main, connecting the defunct McCullens Avenue plant
to the new Eel River Treatment Plant. These sewer mains were
placed in the maintenance dike housing the water line, from Del
Norte Street to just north of the RR Marsh, where the lines run
towards and follow the railroad right-of-way. This caused the
culvert, which previously drained the marsh, to be removed and
two 12" PVC pipes to replace it at a higher elevation.

3.72 Current Land Use

Land uses adjacent to the site generally consist of commercial/
industrial development. To the north is the Halvorson "Flea
Market" Building, City Garbage of Eureka (solid waste refuse
transfer site) and Harbor Lanes Bowling Alley. Del Norte Street
Pier, an unused dock needing repair, is located at the north-
western side of the project site. Along the eastern edge (on
either side) of Broadway Avenue are commercial uses including

3-29

till

-7,

Ike.

NO%

zam

IV
W-M

Alt 4

1939 AERIAL PHOTO

Figure 8

equipment rental, truckstop, motels, and retail stores. Several
-parcels zoned for commercial services uses are vacant or under-
developed. The Maurer Marsh, a 19 acre parcel consisting of ten
acres of freshwater marsh and 9 acres of filled and/or developed
land, is located east of the drying shed area. The Bayshore
Mall,-located south of the project site, is currently being con-
structed; completion date is estimated for November, 1987. Two
wetland mitigation areas for the Bayshore Mall encompass both the
east and west edges of the paved drying shed area. These, for
the most part, have been restored and replanted with wetland/
riparian vegetation.

The Palco Marsh area is currently used for bird watching, social
gatherings, jogging, walking, and retriever training. Clamming
and some incidental fishing occurs in the bay adjacent to both
Del Norte Street and Truesdale Street.

Other uses observed include hunting, pistol shooting, camping and
garbage dumping. Vacant boxcars on the railroad lines show
evidence of past and present transient use. These "sleeping
areas" also occur within the brush vegetation along the borders
of the project area.

3.73 Access

Many access points into the Palco Marsh site currently exist. A
person can drive to or near the site by using Railroad Avenue,
Del Norte Street, Hawthorne Street, Broadway Avenue, Vigo Street
or Mill Street. Pedestrian use, in addition to the above-
mentioned roads, occurs from Truesdale Street through the Mall
construction site, and/or along the Northwestern Pacific Rail-
road tracks. The City's Maintenance dike between Del Norte and
Vigo Streets provides access both along and into the marshes.
Many of the areas within the marsh complex show signs of pede-
strian use.

Indications for Enhancement Planning

Since mixed commercial/industrial land uses surround the project
site, adequate buffers may be needed to protect/enhance the
integrity of the marsh environments. The site, at present, has
uncontrolled access and is made use of in ways contrary to wild-
life values. As the project site becomes restored for wildlife,
increased interest and subsequent use by the public is a. 'ntici-
pated. Providing controlled access for compatible uses will be
necessary to achieve wildlife values for the site.

Access from public streets, where adequate parking is available,
should be encouraged. Parking could be made available along and
at the end of Del Norte Street. Vigo Street, in its unimproved
state, does not have parking available along its width. Should
commercial properties be further developed, street improvements,
including parking lanes could be required. Vehicular access, as

13 - 1@ I

well as parking could be made available at the west end of Vigo
Street. At present, no public easement is available from Mill
Street, the Bayshore Mall, nor the Northwestern Pacific Railroad
right-of-way. Access from these locations should be discouraged
until adequate rights are obtained. Given the access opportu-
nitie*s available, no need for additional access points are
warranted at this time.

On-site pedestrian access includes Vigo Street and the main-
tenance dike from Vigo Street to Del Norte Street. Views of the
site are also available from the Del Norte Street peninsula.

In order to maintain a more perfect union between wildlife and
people, some effort to control use will be necessary. One of the
obvious and simple, though expensive methods, would be to place
fencing around the perimeter of the marsh. This would resolve
most of the problem at the expense of sacrificing the aesthetic
value of the area. Other methods are available and have been
used successfully that not only protects wildlife values but also
provides an aesthetically pleasing environment that allows people
the opportunity to enjoy the area for its natural beauty. These
methods, such as vegetative buffers, ditching along the perimeter
of the marsh, trail improvements and signs, combined with the
increase in public use and surveillance all help to define the
borders for public use.

Access along the railroad rigbt-of-way has been used by people,
bicycles, motorbikes and four wheel drive vehicles. This is also
true for Mill Street. A combination of ditching and vegetative
plantings could be used to limit access to desired areas.

A combination of bumper logs, curbing and vegetation
should be used to define parking areas. Picnic areas should be
located near parking areas. A trail along the top of the main-
tenance dike between Vigo and Del Norte Streets should be clearly
defined. Lateral ditching on both sides of this dike would dis-
courage entrance into the marsh. The project site on the east
side of the railroad right-of-way could be fenced and/or planted
in areas where ditching does not now occur.

The railroad spur, located near Vigo Street, also allows access
from the railroad right-of-way. if this spur becomes part of
this project, the spur should be removed and the berm graded to
wetland elevations. If this spur remains outside of the project,
limited fencing , ditching and vegetative plantings should be
implemented.

Past land use has caused an accumulation of debris throughout the
project site. This gives the image of a neglected area and
encourages further degrading activities, as people's perception
of an area may influence their treatment of it. As such, a con-
certed effort should be made to clean up these areas and
discourage continued misuse.

3-32

The Del Norte Street Peninsula, approximately four acres, is
bordered by Del Norte Street at the north, the Bay on its west
and north sides, and a dredged, drainage/tidal channel along its
eastern edge. This area consists of a filled wetland area
presently topped with grasslands, shrubs and a disused gravelled
and/or paved road. Access to this area from Del Norte Street is
limited by an open ditch and broken concrete rubble. Alarge
gravelled# area, adjacent to this site, provides parking adjacent
to the Bay and for pedestrian access to the pier ruins at the end
of Del Norte Street. Eureka's LCP identifies this area for
coastal access and has hopes of someday repairing the pier struc-
ture.

Periodic dredging of the drainage channel has been necessary in
the past and will probably be needed sometime in the near future.
This necessitates continuous, though periodic, access for inci-
dental dredging and maintenence purposes adjacent to the channel.

4.0 ENRANCENEWT PLAN

4.1 Intrc>duction

The development of the following Enhancement Plan takes into
account agency goals, site conditions, and subsequent discussions
with the City of Eureka, the Coastal Conservancy and other
interested agencies.

The Palco Marsh has been a focus of concern for enhancement acti-
vities by a number of agencies; the Army Corps of Engineers
designated the site as an "Area of Importance" to the functioning
of the Humboldt Bay ecosystem; the California Coastal Commission
included the Palco Marsh on its list of priority public acquisi-
tion sites; and the City of Eureka designated this site in its
Local Coastal Plan for acquisition and enhancement activity. The
City of Eureka requested funding from the Coastal Conservancy for
acquisition and eventual enhancement improvements.

The Coastal Conservancy agreed to provide funding to acquire, plan
and restore the Palco Marsh site with three primary objectives:

1. Enhance tidal action in the Palco Marsh.

2.' Remove fill in drying shed area and restore to marsh
habitat.

3. Assemble land in the project area to improve future
management.

The initial enhancement phase involved a site inventory and
identification of opportunities and constraints. This was
completed in Section 3.0. The principle findings and oppor-
tunities for enhancement planning, summarized with goals
developed by subject area, are listed below.

4.2 Site Analysis Results and Goal Development

4.21 Topography, Geolocjy and Soils

Site topography, geology and soils are suitable for wetland
restoration. Excavation will be necessary in some areas to pro-
vide channels to distribute tidal input in the salt marsh area
and establish elevations which will provide open water in the
freshwater marsh area. The paved drying shed area, which is
several feet above native wetland soils, will require significant
amounts of material to be graded to wetland elevations. Fill
will be required for planting along proposed roadside buffer
areas. Construction activities could subject wetland soils to
compaction.

1. Improve channel capacities to minimize restrictions on
tidal input.

4-1

2. Establish substrate elevations for a 1.5 acre pond conducive
to open water habitat in the freshwater marsh.

3. Remove fill at drying shed area to expose native soils
and establish elevations favorable to wetland development.

4. Design proposed improvements to minimize grading and
equipment operation within existing marsh areas.

5. Utilize construction methods that minimize
compaction (e.g. dragline, crawler tractor). Utilize hand
ditching where feasible.

4.22 Hydrology

Tidal influx and runoff within the Palco Marsh are inhibited by a
faulty tide gate, inadequately sized and improperly placed water
exchange pipes, and inadequately sized channels for internal
water distribution. Groundwater conditions appear favorable for
establishment of freshwater and brackish marsh systems. Flooding
conditions within the Marsh are primarily due to restriction in
run-off drainage from the site. Water quality problems resulting
from on-site conditions will improve with increased tidal
circulation.

1. Improve tidal circulation to Palco Marsh by removing
existing tide gate and install larger capacity pipes at a
lower elevation across the existing City maintenance road.

2. Make selected improvements to existing drainage channels
and construct new drainage channels to improve circulation
within the salt marsh area.

3. Construct weirs, culverts and other water control
devices as needed to maintain hydrologic conditions
favorable to planned vegetation improvements.

4. Design new water exchange improvements to avoid
increasing flood event water elevations.

5. Design channels and weirs to promote scour of natural
drainage features in the Marsh that have filled with sediment.

4.23 Vegetation

Salt marsh vegetation west of the railroad is healthy and
diverse; east of the tracks, it is degraded and low in diversity
due to inadequate tidal circulation and insufficient runoff
drainage. This has caused large areas of pickleweed and salt-

4-2

grass to die back, leaving bare mudflat areas. Brackish marsh
vegetation is highly diversified in some areas. Existing fresh-
water marsh vegetation is dense and has choked almost all open-
water areas. Riparian vegetation along the east side of the
marsh site is encroaching westward into the freshwater marsh
habitat. Freshwater marsh vegetation distribution is at least
partially fed by near surface groundwater resources. The drying shed
area and other upland areas presently supports no wetla-nd habitats.
Invasive exotic species have become established in several loca-
tions in the marsh, as well as upland areas. Populations of rare
plant species, located outside of degraded salt marsh areas and
west of the railroad right-of-way, will not be affected by.
Enhancement activities should encourage further development.

1. Maintain existing overall vegetation patterns within the
Palco Marsh complex.

2. Improve degraded salt marsh conditions in the Palco
Marsh to pre-1981 conditions or better by hydraulic
improvements and natural plant propagation.

3. Provide approximately 1.5 acres of submergent marsh
(open water) area in existing cattail dominated habitats and
in the Palco Marsh.

4. Rehabilitate RR Marsh to provide salt marsh habitat
adjacent to existing salt/brackish marsh habitat.

5. Excavate existing upland areas along railroad spur to
RR Marsh habitat.

6. Provide riparian screening along roadways and commercial
development.

7. Reduce or eliminate existing invasive exotic plant
species populations to the extent feasible.

4.24 Wildlife

Wildlife use of salt marsh habitat at the Palco Marsh is
extremely low, both in numbers and diversity. This is primarily
due to the lack of adequate invertebrate food sources resulting
from poor tidal circulation. Use of freshwater/brackish
marsh habitat by wildlife is low due to the lack of open water
areas. None of these areas are receiving the amount of use by
wildlife that would be expected, given its location to the Bay
and surrounding areas.

1. Provide open water areas for waterfowl habitat.

2. Improve density of salt marsh vegetation in Palco Marsh
as habitat for aquatic invertebrates.

4-3

3. Limit public access improvements to margin areas and
design to limit wildlife disturbance.

4. Design channel improvements and ditching to limit public
access into wetland areas.

5. Develop and adopt area use regulations which rimit
disturbances which adversely affect wildlife use.

6. Provide approximately 1.5 acres of submergent marsh
(open water) area in existing cattail dominated
habitats.

7. Provide riparian screening along roadways and commercial
development.

8. Design marsh areas in the paved drying shed area to
maximize wildlife habitat values by removing paving,
fill, grading and providing an adequate water source.

4.25 Public Access

Existing use of site varies widely in type, amount and occur-
rance. The enhancement of the proposed marsh will eventually
result in increasing the number of visitors to the area. Many
current uses now conflict with anticipated enhancement goals.
Access routes are undefined, unimproved and abundant, allowing
for degradation of marsh habitats and wildlife disturbance.

1. Encourage amounts and types of public use which are
consistent with enhancement goals in areas which are
compatible with wildlife habitat use.

2. Provide controlled public access and wildlife viewing
areas consistent with the maintenance of marsh resource
values.

3. Develop a small parking area and interpretive
signs at Vigo Street just east of the marsh complex.

4. Develop a small parking area, trails, viewing areas and
picnic sites at the foot of Del Norte Street.

4.26 Maintenance

As the project's maintenance would be the responsibility of the
City of Eureka, maintenance costs should be minimized.

1. Design improvements to minimize maintenance reau,'rements
and law enforcement demands.

2. Provide attractive public access and viewing areas by
initially clearing debris followed with regular maintenance.

3. Perform preventive maintenance as needed to maintain
target habitats and prevent re-invasion by exotic plant
species of vegetation.

4. Upon project construction, institute a program to
monitor restoration progress, identify shortfalls and
take corrective action.

4.3 Proposed Enhancement Plan Summary

The improvements necessary to accomplish the previously listed
goals include both improving conditions in the existing marshes,
as well as creating wetlands in non-marsh areas. The following is
a summary of the main enhancement implementations by project
area. A map delineating the improvements (Map 1) is located at
the back of this report. Associated cost estimates are listed in
Appendix C.

4.31 Palco, Marsh Complex

1. Remove tide gate.
2. Construct an inverted siphon under the City maintenance
dike.
3. Excavate perimeter channel improvements, extend hand dug
channels as necessary.
4. Construct culverts under maintenance dike to allow tidal
influx to RR Marsh.
5. Remove railroad spur and grade to marsh elevations.
6. Clean out channel between RR Marsh and culvert under
railroad tracks.
7. Remove exotic vegetation and excavate channels in RR
Marsh.
8. Replant excavated salt marsh vegetation in Palco Marsh,
RR Marsh and along channels, as appropriate.
9. Excavate permanent open water area in cattail/common
rush vegetated areas; provide resting islands; provide
low dike around open water area; provide adjustable weir.
10. Elevate and maintain existing maintenance dike for public
access and periodic maintenance.
11. Remove exotic plants initially, maintain eradication
yearly.
12. Plant riparian buffer areas along road edges, adjacent
properties and around parking area for screening.
13. Access improvements
- gravel trail, gates, signs and benches along
maintenance dike and Vigo Street;
- sidewalks along Del Norte Street, Felt Street
and Broadway Avenue.

4.32 Paved Drying Shed Area

1. Remove drying sheds and other debris.
2. Remove 40'wide strip of paving outside of proposed
parking area, berm and plant with riparian buffer.

3. Provide vehicular access barriers where necessary.
4. Use remaining paved area for drying dredge spoils from
excavation of channels and open water area.
5. Retain majority of paved area to be removed as part of
"Phase 2" of project.

4.33 Area West of Railroad Tracks

1., Provide public access improvements including parking,
sidewalks information kiosk, picnic area, trail, and an
elevated viewing area.
2. Provide maintenance access for periodic removal of sedi-
ment from drainage channel in the least
impacting manner.
3. Provide a temporary dredge spoils drying area
adjacent to Del Norte Street.

4.4 Alternatives Considered

Several alternatives were looked at within the Palco Marsh
complex but not chosen for this project. These included major
elevation changes in the existing marsh as well as major shifts
in the amounts of different habitat types. Since the goal was to
enhance existing wetland systems, these went beyond what was
necessary. In addition, large scale restoration projects not only
disrupt existing wildlife use but also have questionable success.

Several alternatives were considered for the paved area that
involved grading for varying degrees of salt/brackish or
freshwater marsh habitats, depending on the source of water
utilized. Several nearby water sources, including both tidal and
freshwater from the Bayshore Mall restoration areas and
freshwater from Maurer Marsh, are on private lands and currently
not available. In addition, on-site groundwater resources are
approximately five feet below grade. Potential flooding problems
with the Bayshore Mall project, as well as untested success of
the restoration projects (including this project), indicated that
more information was necessary before obtaining the best,
utilization of the surrounding areas. The relative costs
associated with removal of large amounts of paving and fill, in
comparison with costs associated with the rest of this project,
also dictate delay of major enhancement efforts. As "Parcel 4",
the adjacent coastal dependent industrial parcel is developed,
wetland mitigation requirements could be partially fulfilled at
this location. For these reasons, minimum excavation/grading is
presently proposed within this area. The project will become
fully planned as some of the above mentioned constraints are

A-A

removed. This should be undertaken as "Phase 2" for this
project. (See Section 4.9)

Other opportunities for providing additional tidal influx to
Palco'Marsh included constructing a new or larger culvert under
the railroad right-of-way. Major grading would be necessary in

the Bay, as well as the Marsh to take advantage of any benefits.
A drainage structure, at the northwest corner of the Palco Marsh,
also would allow additional but limited opportunities for tidal
and freshwater runoff influence in the Marsh. This had the
potential of causing the storm drain system to back-up during
peak storm flows. In addition, a more centralized location for
tidal exchange seemed more appropriate for meeting the goals of
this project. This drainage structure would be an option in the
future if site conditions or management goals warranted. Another
option was to keep the RR Marsh drainage separate from the Palco
Marsh. Tidal influx is now partially blocked by the 36 inch
sewer line that crosses the channel between the railroad
right-of way and the maintenance dike. Tidal input would be
increased if flow lines of the ditch were excavated below the sewer
line. This option may be beneficial to the Bayshore Mall
Restoration Project and should be further developed as part of
Phase 2 of this project-

Additional open water areas could be provided in the interior of
the fresh/brackish marsh without use of heavy equipment. This
would be accomplished by utilizing a technique, not common in
Coastal California, but used extensively in the Mid-West and
Northeast portions of the United States to open marsh areas for
wildlife use. This involves placing small amounts of Ammonia
Nitrate fertilizer in various locations and detonating it with an
electric charge. This method could create several 20 x 20 foot
freshwater pond "holes", which could have a life expectancy of
10-15 years before infilling again. This is a low cost method
which is less intrusive than heavy equipment use. State certifi-
cation for use of explosives is required. This alternative was
not further pursued though its application at this site seemed
-appropriate. Additional research as to its applicability to this
area should be pursued by an appropriate resource agency, and if
feasible, applied to this site.

4.5 Proposed Enhancement Plan - Construction Aspects

The Enhancement Plan has been designed to minimize construction
impacts on non-involved areas of the Marsh. This included avoid-
ing the use of heavy equipment in the middle of the marsh. Except
for the excavation of the open-water area in the infilled fresh-
water marsh and the central inlet channel, most of the proposed
improvements can be completed from adjacent upland areas.

Overall clean-up of the site should be completed and temporary
access controls should be installed as soon as possible. Signs
describing the future enhancements efforts should be installed at

A -

the existing access points: Vigo and Del Norte Streets.
Monitoring programs should begin baseline data collection prior
to construction.

4.51 Palco Marsh Com2lex

The tide gate at the Bay will be removed after the construction
phase of the project. Until then, and just-prior to construction,
the gate should be put into operating condition and left in place
to temporarily eliminate tidal input during construction. The
flapgate should be stored for temporarily reinstallment if required
for maintenance purposes.

Construction of the inverted siphon will involve placing two 18
inch culverts under the sewer lines which are enclosed in the
City maintenance dike. The flow line will be approximately at
0.0 foot (City Datum). A weir box will be placed at both ends of
the 18 inch pipes to allow manipulation of water levels. These
boxes will be covered with a debris screen for public safety
purposes. Since the flow line elevation in the culvert that
brings in tidal input is at 3.7 foot, all areas in this structure
and within the Marsh below 3.7 foot elevation will be inundated.

The weirs will be adjustable from 3.0 to 7.0+ foot elevation,
allowing a wide range of marsh management goals. Initially the
weir should be set at 3.0 feet elevation. This allows the maxi-
mum amount of both tidal input and run-off drainage.

Channels will be constructed with flow lines beginning at about
3.0 foot elevation in the marsh, one towards the east, 200 feet,
and two others adjacent to the maintenance dike; one north for
500 feet and one south to Vigo Street, 850 feet. Channels will
be approximately 3 foot wide. Flow lines will gently slope from
3.0 feet at the inlet to 4.5 feet at the channel ends. Sides
will be sloped at 2:1. Smaller channels, two foot wide, one foot
deep 14,0-4.5 foot elevation) will be hand dug in locations where
several existing channels have filled with sediment, as indicated
on on the Enhancement Plan Map.

The hydraulic modeling, developed as part of the site analysis
for this project, indicates that these improvements will increase
both tidal fluctuation into the Marsh and run-off drainage from
the Marsh. Figures 9 a, b, c, and d (pages 4-9, 4-10) depict
both present and expected water level fluctuation during a normal
tidal cycle and during periods of storm run-off. Figure'9a shows
a typical tidal fluctuation in the Bay overlaid with the existing
muted tidal prism, as well as the tidal variation expected from
the proposed improvements. As depicted, the Marsh will be sub-
ject to a diurnal tidal cycle and in-phase with the tides occur-
ring in the Bay. Maximum water levels will remain approximately
where they currently exist. Minimum water levels will approach
channel bottoms elevations. Table 6 compares tidal water eleva-
tions, volume and inlet velocities for both present and proposed

4-8

NORMAL CONDITIONS, NO PRECIPITATION (A)

-TIDAL PRISM IN BAY

6--

MARSH
IDAL PRISM IN
(PRESENT CONDITIONS)

C3 -TIDAL PRISM IN MARSH
5
(PROPOSED IMPROVEMENTS)
Li
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0 20 40 50 so 100

TIME IN HOURS

TWO YEAR STORM (B)

7 -

PRESEIV7.
Co)vDjTjOjVS

/* '900s
L)
s

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0 20 40 60 80 100

TIME IN HOURS
ENHANCEMENT PLAN
4-9 TIDAL PRISM / STORM RUNOFf
Figure 9 (AaB)

10 FOOT TIDAL SURGE, 10 AND 100 YEAR STORMS (C)

TIDAL FLUCTUATION IN SAY

8--

QIOO,PRESEN
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0100, PROPOSED
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TIME IN HOURS

FEBRUARY 15 THROUGH 18, 1986 CONDITIONS (D)

PRESENT CONDITIONS

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PROPOSED IMPROVEMENTS

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TIME IN HOURS
ENHANCEMENT PLAN
4-10 TIDAL PRISM / STORM RUNOF
F i cr ii r p- Q (r Pi n

a I _J
(D 1 1
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A

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Marsh
-To Bay

..Adjustable Weir
3.0 to 70
2 - 18 PVC Pipes
Of ili'@'Corr. PIpe

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Scale: I"=10'

V
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0 q 00
-To Buy E,
Cy Grove I
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10 Debri Roadway
Minimum Width 16 Ft. Debris
Screen El. 8.3 Screen
Adjuslable Weir
3.0 to 7.0 A= -Adjustable Wi
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5 24"Corrugated Pipe _J
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- - - - - - - - - - IN
El.t 3.0
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2- 18"PVC Pipes

0 10 20 40 50
"30

ELEVATION
Scale: Horiz. I"TIO,
Vert. 1 ..2 5t
City Datum ENHANCEMENT PLAN-
TIDAL EXCHANGE AREA

4-11 Figure 10

conditions. Figure 9b represents the response of the marsh to a
"two-year flood". As depi6ted, the present conditions depict an
extended drainage time required (58 hours after the peak) before
reaching normal water surface elevation. With the proposed
improvements this time is reduced to 14 hours. Figure 9c depicts
the response of the marsh to extreme flooding events for both
present conditions and with proposed improvements. Flood level
water elevations will not be significantly increased and should
be somewhat lower than depicted on the graphs; the higher levels
shown represent a six hour precipitation event coinciding with a
10 foot tidal surge. Proposed improvements will improve drainage
under most flood conditions. Though peak water elevations will
remain the same, run-off will be discharged from the site at a
more expedient rate. Table 7 compares response of the marsh to
the proposed improvements.

Figure 9d depicts modeling results, which represented conditions
occurring in February, 1986 (See Section 3.32). With the proposed
improvements, water levels in the Marsh would respond by rising
and falling after each precipitation event, drastically reducing
the opportunity for water levels to build up and subsequently
flood adjacent properties.

A 1.5 acre open water area will be created in the southeast
corner of the Marsh which will replace dominant cattail vegetated
areas. The pond will be "L" shaped, approximately 100 feet across
with several island areas. Bottom elevations will be at 0.0 feet
sloping upwards to existing elevations of 6.0 feet. An eight to
ten foot wide dike, at approximately 7.0 foot elevation (6-12
inches high) will be placed around the north, west and south
perimeter. Natural overflow will occur over the dike. An
adjustable weir will be installed at the western end of the open
water area to allow adjustable pond heights between 3 and 7 feet.
This design incorporates measures that will lessen the current
problem of backflooding into the Mauer Marsh and improve the
draingage during flood conditions.

Excessively wet conditions in the open water area may require
temporary fill to be placed in the construction area and utilized
as a road to transport materials from the area. Fill materials
will come from the paved area. This fill would be removed as
surrounding excavation is completed. Several islands will be
left intact as resting islands for wildlife. Fill that is
removed may be utilized for the raised viewing platform on the
Del Norte Street Peninsula.

RevegetatLion within the salt marsh will be limited, for the most
part, tc along the upper edges of the newly constructed channels.
This will involve planting salvaged pickleweed and salt grass
from excavated areas. The interior areas of the salt marsh, which
have experienced die-back of vegetation, may take a year or two to
have conditions conducive to revegetation. Natural revegetation
should be adequate once healthy conditions return.

4-13

Salt marsh areas will be allowed to develop naturally under the
influence of tidal circulation in the site and natural seed
dispersal from the surrounding areas. Natural development of
wetland vegetation should be favored by slow water currents and
nearness of seed sources. Target species include pickleweed,
saltgrass, jaumea and arrow grass. Water level management (pre-
soaking of seeds) is an option that can be undertaken by, the
managing entity once the project is underway and specific infor-
mation is available. This will be done by periodic adjustment of
the weir structure at the inlet channel. The open water area
will be influenced by surrounding cattail and common rush vegeta-
tion surrounding the pond. Steep sloping sides will prevent
infilling by cattails, preserving the open water aspect. Sources
of hydracotyl and other submergent vegetation exist in the
remnant pond on the project site.

Plantings of willow and alder will occur at various locations for
screening and buffering adjacent land uses. Solid plantings will
occur along Felt and Del Norte Streets. Periodic clumps will be
planted along the north side of Vigo Street, the east side of the
maintenance dike, and in the picnic area on the Del Norte Street
Peninsula.

Cuttings will consist of three sizes depending on soil moisture
conditions: 1/2", 1" and 2" diameters, approximately 18 inches
long, and should be planted at a density of approximately 2,000
per acre, spaced every 4 feet. Red alders should be inter-
dispersed in the plantings to provide variation in canopy
height, particularly near public access areas.

The four exotic species of concern should be removed as neces-
sary and monitored yearly. This will prohibit re-establishment.
The extent of scotch and/or french broom is limited and can
easily be removed by hand grubbing plants. Care should be taken
to remove this plant with the roots prior to seed development.
Removal during flowering season will aid in identification and
location of plant.

The removal of pampas grass presents a more difficult problem;
but if done with care, will cut down on the intensity of growth
now occurring. The majority of the pampas grass occurs along the
maintenance dike, the railroad right-of-way, the northwest sector
of Palco Marsh, and/or the Del Norte Street Peninsula. Seed
stalks should be removed prior to major disturbance of the plant.
are should be taken not to discharge the wind dispersed seeds.
The majority of the leaves should be cut down to ground level and
C

rock salt should be poured onto the remaining clump.

Specimens located on the peninsula at the marsh edge and along
the side of the maintenance dike can be removed by a backhoe,
removing the rootball intact. The specimens located along the
top of the maintenance dike may be scraped or dug out with special
care not to disturb the underlying water or sewer lines. The
specimens scraped, as well as those located on the railroad
right-of-way will probably require additional hand removal of

4-14

plants. All holes should be examined for evidence of complete
removal of the rootball and subsequently filled with the appro-
priate materials (clean, upland soil/gravel).

Removal of the common reed specimens present also requires
special care. Though specimens are, for the most part, acces-
sible by backhoe, special care is necessary to assure complete
removal. Seed stems should be removed prior to disturbance and
disposed off-site with care not to disperse seeds (burning on-
site is an option). Specimens should be cut down and treated
with rock salt and later, where appropriate, removed by backhoe.
Visual checking and hand clearing should follow. Surrounding
soils, which may contain dormant seeds, should also be scraped
and removed off-site. Since this plant propagates from rhizomes,
special care to remove all roots is necessary. Holes left from
removal of plants, if not part of designed excavation plans,
should be filled so as not to provide ponding for mosquito repro-
duction. Since this plant seems to be limited to stressed
brackish marsh habitats, increasing tidal actions should elimi-
nate this concern.

Gravel fill will be placed on top of the maintenance dike to a
minimum elevation of 8.5 feet and will serve as the main pede-
strian access to the site. Public access will be available from
the Vigo Street entrance, along the paved road and unto the
gravelled surface trail to Del Norte Street. Each end of the
maintenance dike will have a walk-around entrance gate that
allows pedestrian access, as well as a locked gate for main-
tenance purposes. Project identification and usage signs will be
posted at each entrance. Eight benches will be placed at various
locations between the Vigo Street entrance and Del Norte Street.

4.52 Paved Pa Shed Area / Railroad Marsh

The drying sheds should be sold as surplus property or put out to
bid for salvage/removal. other debris, left from use of the mill
site, including remnants of a burned shed, fencing and the
railroad spur should also be removed.

Directly at the end of Vigo Street a 100 x 200 foot paved area
will be reserved for parking. A 40 foot wide strip of paving and
fill will be removed from the south and west sides of the parking
area to construct a barrier for vehicular access onto the remain-
ing paved areas. This barrier will consist of a combination of
berms, ditches and willow plantings. If poles were available
from the salvaged drying sheds, these could be used as either
bumper logs or as fence posts for an additional access barrier.
A locked gate will allow access to the remaining paved area for
future enhancement and maintenance purposes. Vehicular access
from Mill Street to the paved area will be discouraged by a
combination of fencing, berms and plantings.

The RR Marsh will be excavated and initially used as a settling
basin for drainage from dredge spoils. The drainage ditch that

4-15

currently exists between the railroad right-of-way and the
maintenance dike will be cleared of debris and graded to 4.1 foot
elevation for a distance of 400 feet. Two 12 inch culverts will
be placed under the maintenance dike just south of where the
sewer line crosses the ditch. New channels in the RR Marsh will
be excavated to 4.0 foot elevation, the railroad spur will be
graded from 5.5 foot to 8.0 foot elevation. A channel will
extend from the RR Marsh south adjacent to the railroad r.ight-of-
way 300 feet. This would limit vehicular access to or from the
railroad right-of-way.

The unused, paved area could serve as a temporary area for
drying and storing channel dredgings from this project. This will
be particularly important for handling the saturated, organic
soils removed from the freshwater open water pond. The area
would be bermed to direct drainage towards the RR Marsh.

4.53 West of Railroad Tracks

Improvements west of the railroad right-of-way are limited to
that portion located on or adjacent to the Del Norte Street
Peninsula. A twenty spaced paved parking area will be provided
off the end of Del Norte Street to be used as access to this
project, as well as the Del Norte Street pier, if and when recon-
struction of that project occurs. Sidewalks will extend to the
end of Del Norte Street. An information kiosk will provide edu-
cational information of the project site. Curbing and fencing
will limit vehicular access to the paved parking and street. A
half acre flat area will be designated as a picnic/play area just
south of the parking area and will be planted with native trees
and shrubs around its perimeter. Typical species will include
wax myrtle, ceanothus, shore pine, willows and alders. Restrooms
are not being proposed as part of this project but allowances
have been made to locate them adjacent to the parking area. An
area directly east of the parking area will be reserved for
future parking needs. Non-saline soils and fill removed from the
paved drying shed area will be deposited towards the southern end
of the peninsula to form a 4 foot high viewing area.

The existing drainage channel/slough between the peninsula and
the railroad right-of-way tends to fill in, and needs periodic
dredging. Bank slumping also occurs along both sides of the
channel. According to City staff, maintenance of the channel
occurs approximately every ten years. Dredgings from the channel.
have periodically been stored in an area adjacent to Del Norte
Street and removed when dry.

A maintenance road will be constructed along the channel and
connect to the existing gravelled roadway-This will be used as a
trail for pedestrian use. A four foot wide trail will extend
onto the viewing area mound. A steep bank, at the southern end of
the viewing mound, in addition to blackberry or willow plantings,
should discourage access into the fragile, narrow salt marsh
bluffs at the southern end of the peninsula.

4-16

4.6 Operation/Maintenance

Facilities required for safe and effective operation and mainten-
ance of the wetland site should be monitored and repaired as
needed. Facilities to be maintained include the inverted
siphon/water exchange improvements. This will include periodic
sediment removal from both sides of the culvert and potential
flushing of pipes. This should be inspected and corrected as
needed previous to each rainy season and after each substantial
storm event. Weir adjustment may also be periodically altered to
obtain a preferred management goal. Other facilities to be main-
tained include the maintenance road, Vigo Street, parking areas,
fencing, gates, signs, and culverts. Collection of litter and
trash will be periodically needed, as well as street sweeping the
parking areas and brushing the road sides.

4-17

4.7 Monitoring

Monitoring the site for hydraulics, vegetation, invertebrates,
wildlife and mosquitoes will be necessary for several years after
construction is completed to ensure that enhancement goals are
satisfied and to develop a management plan for the area.

Monitoring should started prior to the construction phase to
develop baseline conditions. This will be necessary to determine
changes as a result of this project. In addition, yearly reports
should be compiled to compare findings in the various mentioned
disciplines described below

Hydraulics

1. Monitor water levels in the marsh over a complete tidal
cycle quarterly, and at least once during or after a two
year storm event to compare with hydraulic modeling
results. Observe flow patterns and velocities, identify
restrictions or flow problems and adjust weirs to
decrease/increase velocities.
2. Utilize results to fine tune the system to meet
management goals.

Anticipated Schedule: 10 person-days per year, 2 years

Vegetation

1. Prior to construction, establish representative test
plots in existing stressed and healthy salt marsh areas.
Inventory for species presence and density prior to
improvements. Recheck and evaluate once a year, for
years 1, 2 and 4. If significant progress does not occur
after year 4, make adjustments consistent with wildlife
use analysis.
2. Yearly obtain and review aerial photographs of the
project site, as well as adjacent wetlands .

Anticipated Schedule: 10-15 person-days per year, 4 years

Invertebrates

1. Prior to construction, establish representative test
plots in existing stressed and healthy salt marsh areas.
Inventory for species presence and abundance prfor to
improvements. Recheck and evaluate after year 1, 2 and 4.
Correlate with wildlife use of the site, particularly during
fall migration of shorebirds.
2. Locate and monitor development of rare species habitat
range.

Anticipated schedule: 5 person-days per year, 4 years

4-18

Wildlife

1. Starting in the fall of 1987, census the area seasonally
for 3 years, at different times of day and tidal cycle.
Correlate information with local birdwatcbers for changes
in wildlife use. Identify available food source development.

Anticipated schedule: 10-15 person-days per year, 3 years

M's quitoes

1. Review recommendations from County Health Department's
monitoring of site to identify problem areas. incorporate
needs into management goals to minimize problem.

A-1 9

4.8 Permit Requirements

This enhancement project will require several permits from local,
State and Federal agencies. Permit types and approximate
processing time requirements are listed below:

1. City of Eureka - Approval of Development Plan,
processing of CEQA document. Processing time: @30-45 days

2. Humboldt Bay Harbor, Recreation and Conservation
District - permit for all construction in areas below
MHHW. Processing time: 45 days

3. California Coastal Commission - Coastal Development
Permit for construction within CCC permit jurisdiction
Subject to review and concurrence from Department of
Fish and Game. Processing time: 90 days

4. U.S. Army Corps of Engineers - Permit for construction
in all wetland and slough areas pursuant to Section 404
of the Clean Water Act and Section 10 of the Rivers and
Harbors Act. Subject to review by U.S. Fish and
Wildlife Service, California Department of Fish and
Game, Regional Water Quality Control Board and others.
Processing time: 90 days

5. California Department of Fish and Game - 1603 Permit for
work in wetland and sloughs. Processing time: 30 days

6. Eureka Southern Railroad - Permit required to construct
any work within the railroad right-of-way.
Processing time: less than 30 days

Permitting requirements of the resource agencies are interlocking
and interdependent as to timing. For example, the Coastal
Commission will not accept an application until the Harbor
District has acted, and the Corps of Engineers will not process
an application until the Coastal Commission has accepted an
application. Permitting processes will probably require a total
of approximately six months to complete.

This enhancement project, within the city limits of Eureka,
constitutes a "development" project and, therefore, is subject to
similar requirements of other projects. The City requires that
any project which is the "final development" of a parcel will be
improved to current standards, for, amongst other things, street
improvements. The Palco Marsh project site fronts three7sections
of public street; Del Norte Street, Felt Street and Broadway
Avenue. Discussion with City officials indicates that six foot
sidewalks will be required as part of the "development" of this
project. This will require placing some fill adjacent to the
Marsh edges.

4-20

4.9 Future Enhancement Work, "Phase TwoO

Removal of the majority of paving and fill in the drying shed
area will occur at a later time, probably in conjunction with
development of 'Parcel 4' as mitigation. An Enhancement Plan
should be developed of this area which will include the
surrounding restoration and enhancement areas. Results from
monitoring and fine tuning the systems, and any overall required
improvements, should be included in conjunction with future
enhancement work.

One alternative would involve removing all asphalt and fill from
the project site, grading slopes towards a central channel and
providin g a large open water area, which would overflow into the
Palco Marsh (Figure 11). Estimated construction costs (1987)
associated with removal of materials from the remaining 5 acre
site, considering the above enhancement alternative, are listed
below.

Removal of asphalt 220,000 sf $22,000

Excavate to 71 elevation 16,300 cy $130,000

Excavate a 20 square foot
channel, 700 feet long 520 cy $4,000

Excavate one acre pond,
5 foot deep 8,000 cy $64,000

Adjustable weir structures 2 ea $4,000

Revegetation Lump Sum $8,000

Monitoring $ 6,000

TOTAL $238,000

4-21

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ENHANCEMENT PLAN
CONCEPTUAL PHASE TWO
4-22 Figure 11

City of Eureka, Department of Public Works, Miscellaneous
Elevation Datum Relationship.

City of Eureka, Department of Public Works, Storm drainage maps
and information.

Everson, R.E., Geology and Groundwater Features of the Eureka
Area Humboldt County, California. Geologic-@Tl '@-urvey water
Supply Paper 1470. 1959.

Federal Emergency Management Agency, Flood Insurance Study, City
of Eureka, CA, Humboldt County. Revised Map June 17, 1986.

Gerstenberg, R.H., A Study of Shorebirds (Charadrii) in Humboldt
Bay, CA 1968 to 1969. Masters Thesis/Humboldt State
College, June 19 .

Humboldt Bay Harbor, Recreation and Conservation District.
Humboldt Bay Master Plan, July, 1975.

Josselyn, M. 1983. The ecology of San Francisco Bay tidal
marshes: a community profile. U.S. Fish and Wildlife
Service, Division of Biological Services, Washington, D. C.
FWS/OBS-83/23. 102 pp.

Josselyn, Michael, 1982. Wetland Restoration and Enhancement in
California California Sea Grant Report No.. T-CSGCP-007
Koplin, J.R., Franklin, A., and G. Newton. 1984. Elk River
Wildlife Monitoring Project, Final Report. Unpublished
summary report available from the City of Eureka.

LSA (L. Seeman and Associates). 1985. Wetland restoration plan,
Bayshore Mall. Unpublished final report available from the
City of Eureka.

LSA, 1986. Eureka LCP mitigation bank wetland restoration plan.
Unpublished report available from the City of Eureka.

Mason, H. 1957. A flora of the marshes of California.
University of California Press, Berkeley.

Monroe, G. 1973. The natural resources of Humboldt Bay.
Unpublished report available from the Department of Fish and
Game, Eureka.

McKee, M., A Preliminary Assessment of Flood Control Alternatives
in the Bicol River and Estuary, Philippines, U.S. Agency for
International Development, 1983.

Nestler, J. 1977. Interstitial salinity as a cause of ecophemic
variation in Spartina alterniflora. and Spartina cynocuroides
in Georgia coastal marshes. Estuarine and Coastal Marine
Science 5:707-714.

R-2

Newton, G. 1984. Vegetation mapping of proposed wetland
mitigation sites on Humboldt Bay. Unpublished report
available from Humboldt County.

Newton, G. 1985a. Proposed wetland mitigation sites: Belcher,
Ford, and Lambert: Botanical Survey. Unpublished report
available from Humboldt County.

Newton, G. 1985b. Botanical review and recommendations for the
second and third slough sewer line project. Unpubdished
4 report available from the City of Eureka.

Newton, G. 1986. Botanical review and recommendations for the
Palco Marsh Enahncement Plan. Unpublished report available
from the City of Eureka.

Parrondo, R.T., J.C. Gosselink, C.S. Hopkinson. 1978. Effects
of salinity and drainage on the growth of three salt marsh
grasses. Botanical Gazette 139:102-107.

Philip Williams & Associates, Design of Bayside Mall Marsh
Restoration Project, 1986.

Pinder, G.F. and W.G. Gray, Finite Element Simulation in Surface
and Subsurface Hydrology, Academic Press, New York, 1977.

Rogers, J.D. 1981. Net Primary Productivity of Spartina
foliosa, Salicornia virginica, and Distichlis spicata in
Salt marshes at Humboldt Bay, California. Unpublished
master's thesis, Humboldt State University, Arcata, CA.

Shapiro and Associates, 1980. Humboldt Bay Wetland Review and
Bayland Analysis. Prepared by Shapiro and Associates for
the U.S. Army Corps of Engineers, San Francisco District.
August, 1980.

Smart, R.M., and J. W. Barko. 1980. Nitrogen nutrition and
salinity tolerance of Distichlis spicata and Spartina
alterniflora. Ecology 61:630-638.

TerraScan. 1979. Marsh Enhancement Plan and Draft EIR Phase II
- Arcata Marsh Enhancement Project. Prepared for California
Eo-astal conservancy and City of Arcata.

United States Department of Commerce, NOAA, Tidal Bench Marks,
Bucksport, Humboldt Bay, 1981, CA-941-8778.

nited States Department of Commerce, NOAA. Climatological Data
of California, Environmental Data Services. 1986.
U

United States Fish and Wildlife Service. 1979. Classification
of wetlands and deepwater habitats of the United States.
U.S. Fish and Wildlife Service, Biological Services Program,
Washington, D.C. FWS/OBS-79/31

R-3

Willis, R. and McKee, M. 1985. Hydrologic anaylisis for the
Palco Marsh Enhancement Plan.

Zedler, J.B. 1982. The ecology of southern California coastal
salt marshes: a community profile. U.S. Fish and Wildlife
Service, Biological Services Program, Washington, D.C.
FWS/OBS-81/54. 100 pp.

Zedler, J.B., 1984. Salt Marsh Restoration, A Guidebook for
Southern California. alifornia Sea Grant Report No. T-
CSGCP-009.

R-4

APPENDIX A
Some Notes on Circulation and
Sediment in Palco Marsh

1. Circulation and Hydraulic Conveyance

Circulation and the response of the marsh to tidal fluctuations will be greatly improved
from present conditions by modifications of the marsh inlet and widening and
deepening of channels within the marsh. Circulation will be most improved if larger
channels (approximating the original marsh channels in size and cross sectional area)
can be constructed to connect the proposed marsh inlet weir to the historic channels in
the north and south marshes. It is important that the flow line for these channels be
lowered to the three- to four-foot level. In addition to improving marsh circulation,
these channels would (a) be less likely to choke with bottom and emergent vegetation
or slump or experience bank failure (which would decrease channel conveyance and,
in time, cause decreased flows within the marsh), and (b) limit public access to the
marsh area and thereby provide a measure of site security. In the long term, the size of
these channels will be key to preservation of improved marsh hydraulics and lowered
associated maintenance costs.

2. Potential for Scour and Deposition of Sediment

By increasing the conveyance of the channels within the marsh, much higher flow
rates will be achieved but, because of the larger channel cross sectional areas,
maximum water velocities will remain low, probably smaller than 1 foot/sec for the
typical tidal cycle. Throughout most of the tidal cycle, velocities will be much lower
than this. This implies a potential for sediment deposition, and the aggradation of the
present marsh channels is evidence of this. However, the proposed channels would
be at a lower elevation than the present flow line, as would be the inlet/outlet. This
might ensure that the present high bottom elevations would not return, but might also
invite scour.

The prediction of deposition and scour is not an exact science. For example, the
Bureau of Reclamation recommends that, in designing earth-lined or unlined canals,
several tests on soil particle size, plasticity, shear strength, and tractive force be made.
From these data, the resistance to scour can be theoretically estimated, but even these
sophisticated descriptions of scour potential must be evaluated on the basis of
experience for the probable effects of cohesion, which is still beyond the capability of
sediment theory to predict.

For the proposed conditions in the Palco marsh, a potential control mechanism for
both circulation and sediment deposition/scour is the weir inletloutlet gate. By
lowering the elevation of the gate, higher channel velocities will be achieved in the
marsh, thereby implying better circulation and possible scour of channels that might
have been aggrading at a higher gate setting. Conversely, a higher gate setting will
lower the marsh channel velocities and reduce the potential for scour or increase the
possibility for deposition. The point of this is that the flow control mechanism that is
proposed for the marsh might also act, to a certain extent, as a device for regulafing. the
behavior of sediment in the marsh. The proper settings of the gate to achieve desired
circulation and sediment control goals will only be found by experimentation after the
gate is installed.

A-1

APPENDIX B

VEGETATION DESCRIPTIONS

The vegetation of the site is described in the following
discussion. The delineation of each vegetation type (or plant
assemblage) is based on species composition, quantitative
variations, and structure.

Salt Marsh -- SM

The salt marshes on the site are located in a narrow band west of
.the railroad tracks and in a broad area east of the tracks. The
salt marshes west of the tracks contain the usual diversity of
vascular plants typical of salt marshes around Humboldt Bay. In
this narrow strip of marsh, the three dominant salt marsh
species.. pickleweed (Salicornia virginica), cordgrass (Spartina
densiflora), and salt grass (Distichlis spicata) occur together
in varying amounts. Occasional throughout-these marshes are sea
lavender (Limonium californicum var. californicum), jaumea
(Jaumea carnosa), and arrow grass (Triglochin spp.). The rare
Humboldt Bay gumplant is found along the edges of this marsh and
the salt marsh snail (Ovatella myosotis) is common in this
location.

The salt marshes and extensive mud flats east of the tracks are
degraded and lack much of the diversity common in healthy salt
marshes on Humboldt Bay. With the exception of the three main
salt marsh species -- pickleweed, cordgrass, and salt grass --
none of the other salt marsh species occur in this area. The
?nly location that contains a gumplant and a modest population of
Jaumea is a small portion of pickleweed marsh adjacent to the
inlet. Marine infauna are only found near the inlet and the
normally ubiquitous salt marsh snail is absent from these
marshes.

Orache (Atriplex patula) and brass buttons (Cotula corono ifolia)
are common in many of the areas east of the tracks, becoming
dominant in small areas. These species are typically found in
areas that are disturbed or severely stressed. Most likely, the
areas more removed from the tidal inlet experience oxygen
starvation and hypersalinity due to evaporation during the summer
months.

One area east of the tracks seems to be eroding at an accelerated
rate. Aerial photos show that the majority of the erosion has
occurred since 1981, with significant differences betwedn 1983
and 1986. Tufts of salt grass from which the substrate has been
eroded still persist in this area.

Since the health of the existing salt marsh east of the tracks is
one of the main concerns of the enhancement project, the
vegetation was mapped in detail. Other marshes on Humboldt Bay

B-1

located at similar elevations are usually dominated by pickleweed
and jaumea. The following vegetation descriptions and codes
relate to the vegetation map of the site.

SM cordgrass/pickleweed/salt grass
(Spartina densiflora/Salicornia virginica/
Dl-stichliE spicata)

The three salt marsh species do not form distinct zones-within
these marshes because the marsh has formed behind a steep bank
and lacks a gradual interface with the bay and with tidal
inundation, except during the highest tides. Generally, the
species occur either in equal amounts, or with pickleweed
dominating up to 70% of the vegetative cover. This salt marsh is
only found west of the tracks. In addition to the dominant
species, other species such as sea lavender (Limonium
californicum var. californicum), jaumea (jaumea carnosa), arrow
grass (Triglochin spp.), Humboldt Bay gumplant (Grindelia stricta
ssp. blakei), sea plantain (Plantago maritima ssp. juncoides),
and mud-spurry (Spergularia marina) can be found. These
additional species are generally lacking east of the tracks. The
overall height of the vegetation varies from 0.66 feet (20 cm) in
a pickleweed dominated area to 2.3 feet (70 cm) in a cordgrass
dominated area; cover is usually 100%.

SM 2 -- pickleweed
(Sallcornia virginica)

These marshes, which are dominated by pickleweed, are found east
of the tracks in areas directly affected by tidal inundation.
The pickleweed occurs in monotypic stands or as the dominant with
salt grass (Distichlis spicata) and orache (Atriplex patula).
Salt grass is usually less than 10% of the cover and oracbe can
'
be as high as 50% of the cover (occasionally more). The height
of the vegetation averages 0.98 feet (30 cm); cover is 100%.

SM3 -- salt grass
(Distichlis spicata)

The salt grass marshes are at the upper limits of the salt
marshes and intergrade with the various brackish marshes and
upland grasslands. in this vegetation type salt grass is the
dominant plant; pickleweed is present but only in scattered
patches. Orache is present usually with less than 25% cover, and
brass buttons and water foxtail are occasionally present. The
height of these areas averages 0.82 feet (25 cm); cover is 100%.

SM4 -- salt grass/barley
(Distichlis spicata/Hordeum sp.)

This vegetation type is very similar to the previous type. Salt
grass is the dominate species. The main distingui,shing feature
is the addition of various grass species. These grass species
are present in small numbers, but are consistently found
intermixed with the salt grass: water foxtail (Alopecurus

B-2

genticulatus), ryegrass (Lolium perenne), and bromegrass (Bromus
mollis). This assemblage of plants is usually located near the
upper edges of the salt marsh near the upland grasslands. Height
is 1.15 feet (35 cm); cover is 100%.

SKS -- pickleweed/salt grass/orache
(Salicornia virginica/Distichlis.spicata/
Atriplex patula)

The three salt marsh species --pickleweed, salt grass, and orache
occur in equal amounts. This type of marsh is found east of
the tracks at the middle elevations, above the pickleweed line
but below the salt grass areas. The height varies from 0.46-0.92
feet (14-28 cm); cover is 100%.

SK6 -- salt grass/tufted hairgrass
(Distichlis spicata/Deschampsia caespitosa)

This combination of salt grass and tufted hairgrass (Deschampsia
caespitosa) is found only west of the railroad tracks. A few
species common to dune habitats are also found in these areas:
beach bur (Ambrosia chamissonis), dune tansy '(Tanacetum
douglasii), Tracy's salt rush (Juncus lesueurii var. tracyi), and
sand sedge (Carex pansa). This combination of plants is located
at the upper edge of the tidal marshes in areas underlain with
sand dune soils. The height of the vegetation varies from 0.82
feet (25 cm) in the absence of tufted hairgrass to 2.95 feet (90
cm) in the presence of the hairgrass; cover is 100%.
SK,,;- salt grass/water foxtail
(Distich spi ata/Alopecurus genticulatus)

Salt grass and water foxtail occur in approximately equal amounts
with up to 10% of salt rush (Juncus lesueurii var. lesueurii),
orache (Atriplex patula), and pacific silverweed (Potentilla
egedii ssp. grandis). This vegetation type is found at the
upper reaches of the salt marshes which border on brackish marsh.
The height of the vegetation varies but is usually 0.82 feet (25
cm); cover is 100%.

Brackish Marshes -- BM

Brackish marshes form at the interface between the salt marshes
and the freshwater marshes. Therefore, the range of salinities
found in these marshes is highly variable in space and time. The
species composition slowly changes as one moves from the areas
near the salt marshes to the areas near the willow swamps or
riparian woodlands. Three species of plants which are common
throughout these brackish marshes are salt rush (Juncus lesueurii
var. lesueurii, pacific silverweed (Potentilla egidii ssp.
grandis), and water parsley (Oenanthe sarmentosa).

In general, the brackish marshes found on the site are typical of
other such marshes around Humboldt Bay. Two types of marshes

B-3

located on the site that are uncommon around Humboldt Bay are the
pacific rush (Juncus effusus var. pacificus) and the common reed
(Phragmites communis var. berlandieri) stands. The pacific rush
marsh represents a unique resource; the common reed marsh
represents a threat to Humboldt Bay marshes. Though none of the
brackish marshes, or species therein, are rare, the uniqueness of
this site lies in the quantity and diversity of the marshes
represented. Within these parcels, most of the common types of
marshes can be found.

The brackish marshes on the site are separated by species
position and structure. Structure of plant associations is
believed to be very important in ascertaining wildlife uses of
com

the habitat. The brackish marshes vary from very short areas
dominated by grass species to the tall stands of slough sedge
(Carex obnupta).

BM, -- salt grass/water foxtail/
pacific silverweed
(Distichlis spicata/Alopecurus genticulatus/
'Potentilla egedii ssp. grandis)

This brackish marsh is found on the upper edges of the salt
marshes and is influenced by tidal waters. Salt grass, water
foxtail, and pacific silverweed are found in approximately equal
amounts with scattered patches of one or more of the following:
orache (Atriplex 2atula), spikerush (Eleocharis'marostachya), and
brass buttons (Cotula coronopifolia). The height of this marsh
averages 1.48 feet (45 cm); cover is 100%.

BM2 -_ water foxtail/salt rush/velvet grass
(Alopecurus genticulatus/juncus lesueurii var.
lesueuriiUH-ok-us lanatus)

The combination of water foxtail, salt rush and velvet grass
(Holcus lanatus) is found in one area located near the salt
marshes and near a freshwater inlet. This type is very similar
to the previous type with the addition of grass species, most
notably velvet grass and bent grass (Agrostis sp.). Salt grass
and orache are present in this area but with less overall
coverage. The height of the vegetation is 2.3 feet (70 cm);
cover is 100%.

BM3 -- three-corner/salt grass
(Scirpus americanus/Distichlis spicata)

Three-corner (Scirpus americanus) occurs in areas that U.@Ually
have standing water throughout the year. Three-corner mixes with
the salt grass in one area at the upper margin of the salt marsh,
directly off the inlet to the marsh. Very few other species are
associated with this type. Occasionally pacific silverweed
(Potentilla egedii ssp. grandis) and water foxtail (Alopecurus
genticulatus) are included. The height of this type is 2.79 feet
(85 cm); cover averages 85%.

BI-4

BN4 salt rush/pacific silverweed/
common rush/water parsley
(Juncus lesueurii var. lesueurii/Potentilla
egedii ssp. grandis/Juncus effusus
var. brunneuMin-anthe sarmentosa)

This vegetation type is highly variable. It changes dominant
species gradually, from the mudflats to the riparian areas (or
willow swamps). This vegetation type covers the majority of the
brackish marshes east of the salt marshes. The plant assemblage
contains a diverse mixture of species dominated by salt rush
(Juncus lesueurii var. lesueurii) with pacific silverweed
(Potentilla egedii ssp. grandis), some salt grass (Distichlis
spicata), water parsley (Oenanthe sarmentosa), small-seeded
bulrush (Scirpus microcarpus), willow herb (Epilobium watsonii
var. franciscanum), fireweed (Erechities prenanthoides), curly
dock (Rumex crispus), and aster (Aster chilensis).

The dominant rush species changes from the salt rush to common
rush (Juncus effusus var. brunneus) as one approaches the willows
but the species composition remains very similar with two notable
additions. Speedwell (Veronica scutellata) and monkeyflower
(Mimulus guttatus ssp. litoralis) are more common on the eastern
p-ortion of these brackish to freshwater marshes, though still
only present in very low amounts. These two species are much
less salt tolerant and require very wet areas. The height of the
vegetation is variable at this time of year due to the fact that
the salt rush is lying down rather than standing erect; therefore
a range, from 2.79-3.28 feet (85 to 100 cm), gives a better
indication of the structure of the type; cover is 100%.

BK4 -- pacific rush
(Juncus effusus var. pacificus)

Small, 9.8 feet diameter (3 meters), areas occur within the BM4
brackish marsh type that are nearly monotypic stands of a tall
variety of the common rush known as pacific rush (Juncus effusus
var. 2acificus). The species is not common around Humboldt Bay.
The height of these areas is approximately 5.23 feet (160 cm);
cover is 90%. These small patches are denoted as BM4a* The
delineation is mainly due to structure.

B145 slough sedge/water parsley
Warex obnupta/Oenanthe sarmentosa)

This type of brackish marsh is very common around Humboldt Bay in
areas that are seasonally to perennially wet. On Palco Marsh,
slough sedge (Carex obnupta) attains a height of 5.58 fe@et (170
cm). The salinity tolerances of this species are very wide; it
can be found from the upper edges of salt marshes to the
freshwater marshes and willow swamps. The stands on the site
are nearly monotypic, but they can contain small amounts of water
parsley (Oenanthe sarmentosa) and pacific silverweed (Potentilla
egedii ssp. grandis). Cover is 100%.

B-5

----------

BM5a -_ Carex lyngbyei/Oenanthe

Essentially, this brackish marsh is a sub-set of the previous
marsh. It is separated out due to the difference in its
structure. This marsh contains a sedge species which most
closely resembles Lygnbye's sedge (Carex lyngbyei), but which
also contains characteristics similar to slough sedge (Carex
obnupta). The taxonomic uncertainties associated with this
species have been observed elsewhere on Humboldt Bay.

The height of this marsh is 2.95 feet (90 cm); cover averages
98%. Interspersed throughout the culms are the companion species
of pacific silverweed and water parsley, a little more common in
this type than in the previous type.

BM6 -- saltmarsh bulrush
(Scirpus robustus)

The saltmarsh bulrush (Scirpus robustus) stands on the site are
typical of Humboldt Bay nds, which occur in brackish marshes
and in sloughs and channels at the upper reaches of salt marshes.
These monotypic stands require persistent water; other species
are rarely found there. The height of these stands was found to
be 2.30 feet (70 cm). This figure is heavily biased by the time
of year; the majority of the culms are broken and dead. Cover
averages 70%.

BM7 common reed
(Phracjmites communis var. berlandieri)

The common reed (Phragmites communis var. berlandieri) occurs in
the "triangle" near the railroad tracks and in an adjacent area.
This species occurs in dense monotypic stands approximately 8.20
feet (250 cm) in height; cover is 98 %. Common reed is rarely
found in the marshes of Humboldt Bay; as such, this population
may present a threat to the Humboldt Bay marshlands. The need
for eradication of this species was previously discussed.

Freshwater Marshes -- FM

These freshwater marshes are extensive within the site and
intergrade heavily with adjacent riparian areas. Similar
freshwater marshes can be found around Humboldt Bay but are
usually in narrow strips near grazed pastureland.

B-6

FM small-seed bulrush/water parsley/
common rush
(Scirpus microcarpus Oenanthe sarmentosa/
Juncus effusus var. brunneus)

This marsh is found on the "brackish side" of the cat-tail stands
or the riparian areas. These areas are dominated by the small-
seeded.bulrush 'Scirpus microcarpus), occasionally in nearly
monotypic stands, with some amounts of water parsley (Oenanthe
sarmentosa) and common rush (Juncus effusus var. brunneus). The
height of these marshes is 3.28 feet (100 cm); cover is 100%.
This vegetation type intergrades in some areas with the extensive
BM4 -- salt rush/pacific silverweed/common rush/water parsley.
FN2 __ common cattail
(Typha latifolia)

Cattails (Typha latifolia) are the dominant species in this
marsh. The stands can be either closed with a few incidental
species occurring underneath the dense layerof cattails, or the
stand can be more open with various species underneath. The
species likely to found underneath the cattails are pacific
silverweed (Potentilla egedii spp. grandis), water parsley
(Oenanthe sarmentosa), bedstraw (Galium trifidium), willow herb
(Epilobium watsonii var. franciscinum), common rush (Juncus
effusus var. brunneus), monkeyflower (Mimulus guttatus ssp.
litoralis), and slough sedge (Carex obnupta). The height of the
stands averages 7.22 feet (220 cm); cover is 100%.

FM3 __ water parsley/marsh pennywort/
floating fern
(Oenanthe sarmentosa/Hydrocotyle ranunculoides/
Azolla filicuoides)

There is only one location on the site where this marsh occurs in
a large enough area to be mapped. This location is the remnant
of the original freshwater pond present in the 1962 aerial photo
of the site. In this area water parsley (Oenanthe sarmentosa) is
the dominant species with marsh pennywort (Hydrocotyle
ranunculoides) and spike rush (Eleocharis macrostachya) present
in lesser amounts. Duckweed (Lemna sp.) and floating water fern
(Azolla filiculoides) can seasonally cover all the areas of open
standing water. The height of the plants above the standing
water in this marsh varies depending on the presence of the
rooted-emergents, 0.98 feet (30 cm), or the presence of the
floating species, 0.03 feet (1 cm); cover averages 98%. _.

In addition to the one location of this vegetation type included
on the map, this marsh type is found throughout the freshwater
marshes in small openings between plants. These areas, though
important, are much too small to be accurately mapped.

B-7

Riparian Woodlands (or Willow Swamps) -- R

The riparian woodlands on the sites are present in abundance
around the east edges. Two riparian vegetation types are
delineated based on the herbaceous layer. R contains typical
marsh species in the understory while R coniains dense
2.
blackberry hedges and various grass species in the understory.

The areas distinguished as R1, or "wet-site riparian", should be
divided into two types based on the USFWS definitions (USFWS
1979). A forested wetland is 32.8 feet (10 meters) in height; a
scrub-shrub wetland is 23 feet P meters) in height. The western
edge of the Ri area near Highway 101 is slowly encroaching into
the adjoining marshes as evidenced by the large number of alder
and willow saplings in that area. According to USFWS
definitions, the area of encroachment should be designated as
scrub-shrub wetland, while the more mature stand would be
designated as forested wetland (despite its identical species
composition). In effect, the scrub-shrub designation, in this
particular case, is a transitional or successional stage of the
forested wetland.

R, -- willow/alder/water parsley
(Salix spp./Alnus oregona/Oenanthe sarmentosa)

This first type of riparian habitat is currently expanding from
the area near Highway 101. This vegetation type is very similar
in composition and structure to areas described by Newton (in
Koplin et al 1984), Newton (1985a, 1985b). In the canopy layer,
red alders (Alnus oregona) and one species of willow (Salix
lasiandra) reach 30-40 feet (9-12 meters) in height. Other
willow species (S. piperi and S. hookeriana) form a secondary and
shorter layer at7aining 15 feeT_(_Z_.57 meters) in height. The
overall cover of the canopy ranges from 60-90%. The tree species
are invading the adjacent freshwater marshes; many saplings are
becoming established in the marshes.

The herbaceous layer of the riparian habitats is highly
influenced by the type of marsh adjacent to each area, but
typically contains, in dense stands (averaging 80% cover), some
or all of the following moisture loving species: water parsley
(Oenanthe sarmentosa), slough sedge (Carex obnupta), common cat-
tail (Typha latifolia), and small-headed bulrush (Scirpus
microcarpus).

@2 -- willow/alder/blackberry
(Salix spp./Alnus oregona/Rubus spp.)

The second type of riparian habitat is found mainly west of the
railroad tracks in the drier areas. The canopy is usually not as
dense (approximately 40% cover) or as tall as the previous
vegetation type; however, the same species of willow and red
alder are present. The shrub layer is very dense and dominated
by blackberry and himalaya berry (Rubus vitifolius and R.
procerus). The herbaceous layer contains many of the iiime

B-8

species found in the adjacent grasslands such as vernal grass
(Anthoxanthum oderatum) and orchard grass (Dactylus glomerata).

Upland Habitats

G -- velvet grass/common rush
(Holcus lanatus/juncus effusus var. brunneus)

These grasslands are located in areas very near marshes and
contains many weedy species as well as some marsh species. The
dominant grass species is velvet grass (Holcus lanatus). Species
commonly associated with this type are creeping buttercup
(Ranunculus repens), common rush (Juncus effusus var. brunneus),
willow herb (Epilobium watsonii var. franciscanum), and pacific
silverweed (Potentilla egedii ssp. grandis). The height of these
grasslands averages 2.30 feet (70 cm); cover is usually 100%.

G2 -- perennial ryegrass/perennial
trefoil
(Lolium perenne/Lotus corniculatus)

This grassland contains many weedy species commonly associated
with dry areas near the coast. The dominant grass species are
perennial ryegrass (Lolium perenne), vernal grass (Anthoxanthum
oderatum), bentgrass (Agrostis sp.), and orchard grass (Dactylus
glomerata). Other species commonly found in this vegetation type
are dubious clover (Trifolium dubium), Parentucellia viscosa,
english plantain (Plantago lanceolata), anise (Foeniculum
vulgare), beach strawberry (Fragaria chiloensis), and cat's ear
(,Hypochoeris radicata). Height is variable; cover is usually
100%.

B -- blackberry/coyote bush/wax myrtle

This designation is used for small, isolated bushes of any or all
of the following species: blackberry (Rubus vitifolius), himalaya
berry (R. procerus), salmonberry (R. spectabilis), coyote bush
(BacchaFl:-s pilularis ssp. consanguinea), wax myrtle (Myrica
californica), and twin berry (Lonicera involculata). Height and
cover varies with the species.

B-9

"MMIX B. OOMPMM SPBCIES LIST FOR THE PAIM MARSH CCMPIEX

SCIENTIFIC NAME FAMILY COMMON NAME

Achillea borealis Asteraceae yarrow

Agrostis stolonifera Poaceae creeping beent

Aira caryophyllea Poaceae hairgrass

Alnus oregona Betulaceae red alder

Alopecurus genticulatus Poaceae water foxtail

Ambrosia chamissonis Asteraceae beach bur

Angelica hendersonii Apiaceae angelica

Anthoxanthum oderatum Poaceae vernal grass

Aster chilensis Asteraceae aster

Atr@plex patula ssp. hastata. Chenopodiaceae orache

Atriplex patula ssp. obtusa Chenopodiaceae orache

Avena sativa Poaceae oat

Azolla filiculoides Salviniaceae, floating fern

Baccharis pilularis ssp. Asteraceae coyote bush
consanguinea.

Bellis perennis Asteraceae english daisy

Briza maxima Poaceae rattlesnake grass

Bromus mollis Poaceae brome grass

Bromus rigidus: Poaceae soft chess

Calystegia soldanella Convolvulaceae beach morning-glory

Carex lyn2@:Lei Cyperaceae sedge

Carex obnupta Cyperaceae slough sedge

Carex pansa Cyperaceae sand dune sedge

Cirsium sp. Asteraceae thistle

Cortaderis selloana. Poaceae pampasgrass

B-10

SCIENTIFIC NAME FAMILY COMMON NAME

Cotula coronopifolia Asteraceae brass buttons

Cyperus eragrostis Cyperaceae umbrella sedge

Cytisus monspessulanus Caesalpinaceae french broom

.Cytisus scoparis Caesalpinaceae scotch broom

Dactylis glomerata Poaceae orchard grass

Daucus carota Apiaceae Queen Anne's lace

Deschampsia caespitosa Poaceae tufted hairgrass

Dipsacus sylvestris Dipsacaceae teasel

Distichlis spicata Poaceae salt grass

Eleocharis macrostachya Cyperaceae spike rush

Elymus mollis Poaceae dunegrass

EpilcbilLun angustifolium Onagraceae fireweed

Epilobium watsonii var. Onagraceae willow herb
franciscanum

Equistem arvense Equisetaceae horse tail

Erechities prenanthoides Asteraceae fireweed

Festuca. arundinacea. Poaceae meadow fescue

Festuca sp. Poaceae fescue

Foeniculum vulgare Apiaceae anise

Fragaria chiloensis Rosaceae beach strawberry

Fuchsia sp. Epilobium fuchsia

Galium trifidum Rubiaceae bedstraw

Geranium spp. Geraniaceae cranesbill

Grindelia stricta ssp. blakei Asteraceae Humboldt Bay 9-wVlant

Hedera helix Araliaceae English ivy

Heracleum lanatum Apiaceae cow-parsnip

Holcus lanatus Poaceae velvet grass

SCIENTIFIC NAME FAMILY COMMON NAME

Hordeum sp. Poaceae barley

Hydrocotyle ranunculoides Apiaceae marsh pennywort

Hypochoeris radicata Asteraceae cat's ear

Jaumea. carnosa Asteraceae jaumea

Juncus effusus, var. brunneus Juncaceae common rush

Juncus effusus var. pacificus Juncaceae pacific rush

Juncus ensifolius Juncaceae rush

Juncus lesueurii var.lesueurii Juncaceae salt rush

Juncus lesueurii var. tracyi Juncaceae salt rush

Lathyrus latifolius Fabaceae everlasting pea

Lemna spp. Lemnaceae duckweed

Leontodon leysseri Asteraceae hawkbit

Limonium californicum var. Plumbaginaceae sea lavender
californicum

Lolium multiflorum Poaceae Italian ryegrass

L,oli perenne Poaceae perennial ryegrass

Lonicera involculata Caprifoliaceae twin berry

Lotus corniculatus Fabaceae perennial trefoil

Lupinus sp. Fabaceae lupine

Lupinus arboreus Fabaceae bush lupine

Melilotus albus Fabaceae sweet-clover

Mentha pulegium Lamiaceae pennyroyal

Mimulus guttatus ssp. litoralis Scrophulariaceae monkey flower

Myrica californica Myricaceae wax mrytle

Oenanthe samentosa Apiaceae water parsley

Parentucellia viscosa Scrophulariaceae

B- 12

SCIENTIFIC M*E FAMILY COMMW NAME

Phragmites commis var. Poaceae coffmn reed
berlandieri

Plantago lanceolata, Plantaginaceae english plantain

Plantago maritima ssp. juncoides Plantaginaceae sea plantain

Poa annua. Poaceae annual bluegrass

Poa douglasii Poaceae dune bluegrass

Polypogon maritimus Poaceae rabbitfoot grass

Polystichum munitum Aspidiaceae sword fern

Potentilla egedii ssp. grandis Rosaceae pacific silverweed

Prunella vulgaris Lamiaceae selfheal

Pteridium aquil var. Pteridaceae bracken fern
pubescens

Ranunculus repens, Ranunculaceae creeping buttercup

Raphanus sativus Brassicaceae wild radish

Rosa sp. Rosaceae rose

Rosa nutka Rosaceae nutka rose

Rubus procerus Rosaceae himalaya, berry

Rubus spectabilis Rosaceae salmonberry

Rubus vitifolius Rosaceae blackberry

Rumex acetosella Polygonaceae commn dock

Fomiex crispus, Polygonaceae curly-leaved dock

Ruppia maritima Ruppiaceae ditch grass

Salicomia virginica Chenopodiaceae pickleweed

Salix hookeriana Salicaceae hooker's willow

Salix lasiandra Salicaceae willow

Salix piperi Salicaceae dune willow

Sci.rpus americanus Cyperaceae tbree-corner

B-13

SCIENTIFIC NAME FAMILY COMMON NAME

Scirpus microcaxpus Cyperaceae small-seeded bulrush

Scirpus robustus Cyperaceae saltmarsh bulrush

Scrophularia. californica Scrophulariaceae figwort.

Spartina densiflora Poaceae cordgrass

Spergularia marina Caryophyllaceae mud-spurrey

Stachys sp. Lamiaceae hedge nettle

Stellaria. sitchana var. Caryophyllaceae chickweed
bongardiana

Tanacetum douglasii Asteraceae dune tansy

TaraxacLun officinale Asteraceae dandelion

Trifolium dubium Fabaceae dubious clover

Trifolium repens Fabaceae creeping clover

Trifolium wormskioldii Fabaceae cow clover

Triglochin concinnum Juncaginaceae slender arrow grass

Triglochin maritimum Juncaginaceae arrow grass

Typha latifolia. Typhaceae cattail

Veronica scutellata Scrophulariaceae speedwell

Vicia angustifolia var. Fabaceae vetch
segetalis

Zostera. marina Zosteraceae eel grass

B-14

APPENDIX C

ESTIMATED CONSTRUCTION COSTS_
FOR THE PALCO MARSH ENRANCE14ENT PROJECT

Project Quantity Unit Construction
Element Price($) costs M

HABITAT ENHANCEMENT

Water Exchange Improvements Lump Sum 10,000 10,000
(Inverted Siphon/Weir, etc.)

Channel Excavation 87 cy 10 8,750
Hand-ditching 300 If 3.20 960

Open Water Pond Excavation/ 14800 cy 10 148,000
Temp. Road Construction 750 cy 6 4,500

Removal of Drying Sheds Lump Sum 5,000 5,001
Removal of Paving 28,500 sf 0.15 4,275
Gravel 1,600 cy 6 9,600

RR Marsh Excavation 3,200 cy 8 25,600

Maintenance Road
Improvements(gravel) 500 cy 6 3,000

Vegetation Removal/
Revegetation Lump Sum 25,000 25,000

Sub Total $244,685

PUBLIC ACCESS

Del Norte Street Improvements
Parking Area Base 260 cy 25 6,500
Paving 14,000 sf 0.80 11,200
Kiosk Lump Sum 1,000 1,000
Gates 2 ea 400 800
Picnic Tables 4 ea 300 1,200
Raised Viewing Area 2,200 cy 6 13,200

Vigo Street Improvements
Access Barrier/Bumper Logs 1,000 If 1 1,000
Gates 2 ea 400 800
Signs Lump Sum 1,000 1,000
Benches 8 ea 250 2,000

Sub Total $38,700

Sidewalks- Del Norte St. 540 If 54 29,160
Felt St. 600 If 56 33,600
Broadway 530 If 68 36,040

Sub Total $98,800

MONITORING (up to 4 years) 1,000 hrs 30 30,000

Contingency 10% $41,200

OVERALL TOTAL $453,385
C -.1

BROADWAY

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NOAA COASTAL SERVICES CTR LIBRARY

3 6668 14110030 7