Economic and environmental impact of low-head hydroelectric power systems on Guam

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

Coastal Zone
information
Center ALENTOS GIYA GUAHAN-ENERGY ON GUAM

economic and environmental impacts of
low head
y roelectrimc
power systems
on Guam

COAsTAL
INFORMATION

TECHNICAL REPORT NO.8101
Coastal Energy Impact Program
February,1981

TD
195
E4 V
E36
1981

GUAM ENERGY OFFICE GOVERNMENT OF GUAM
h d

P.O. BOX 2950, AGANA, GUAM 96910 * P.O. BOX 2950, AGANA, GUAM 96910*

ECONOMIC AND ENVIRONMENTAL IMPACTS OF

LOW HEAD HYDROELECTRIC POWER SYSTEMS ON GUAM

for the

GUAM ENERGY OFFICE
JAY L. LATHER, DIRECTOR

GOVERNMENT OF GUAM
PAUL M. CALVO, GOVERNOR

Agana., Guam
February, 1981

By
John T. Moore III

marugama & asso,ciates Rd.
P. 0. BOX EF AGANA, GUAM 96910

P;'This report is funded under a grant
ovided by the Coastal Zone Management
Act of 1972, as amended, administered
by the Office of Coastal Zone Management,
National Oceanic and Atmospheric Administration."

TABLE OF CONTENTS

LIST OF TABLES
LIST OF FIGURES

Chapter Page

I. INTRODUCTION 1
A. PURPOSE OF STUDY I
B. CENTRAL IMPACT PROGRAM 1
C. BACKGROUND 2
D. LIMITING FACTORS 3
E. LEGAL ISSUES 5
1. Federal Regulatory Acts Affecting Hydro
Development 5
2. Federal Agencies to Contact in FERC
Prelicensing Process 6
3. State Agencies 6
4. Local Agencies 7
F. STUDY GOALS 8
G. STUDY METHODOLOGY 8
H. SCOPE OF STUDY 11
I. PREVIOUS INVESTIGATIONS AND PRESENT WORK 13
J. ACKNOWLEDGEMENTS 14
NOTES FOR CHAPTER 1 15
II. HYDRO STRATEGIES 16
A. OVERVIEW 17
B. BASIC HYDRO REQUIREMENTS 18
C. HYDRO SCENARIOS 21
1. Plant at Existing Impoundment Area 21
Environmental Impact 21
Potential Sites 22
2. Plant at Proposed Site 23
Environmental Impact 29
3. Plant at Existing Distribution System 29
Environmental Impact 30
4. Plant at Undeveloped Site 30
Cost of Development 31
Environmental Impact 33
5. Small Scale Sites 35
NOTES FOR CHAPTER 11 37
III DESCRIPTION OF THE STUDY AREA AND ITS RESOURCES 39
A. THE STUDY AREA 40
B. HYDROLOGY 54
C. ENVIRONMENTAL RESOURCES 58
NOTES FOR CHAPTER 111 60
IV THE RIVERS 61
A. PAGO RIVER 65
Geophysical Notes 65

Chapter Page

Measurements 69
Power/Head Characteristics 69
B. YLIG RIVER 71
Geophysical Notes 71
Measurements 74
Power/Head Characteristics 74
C. TALOFOFO RIVER 76
Geophysical Notes 76
Measurements 83
Power/Head Characteristics 85
D. UGUM RIVER 87
Geophysical Notes 87
Measurements 98
Power/Head Characteristics 98
F. INARAJAN RIVER 100
Geophysical Notes 100
Measurements 103
Power/Head Characteristics 103
G. GEUS RIVER 106
Geophysical Notes 106
Measurements 109
Power/Head Characteristics 109
H. UMATAC RIVER 110
Geophysical Notes 110
Measurements 113
Power/Head Characteristics 113
I. LA SA FUA RIVER 115
Geophysical Notes 115
Measurements 118
Power/Head Characteristics 118
J. CETTI RIVER 120
Geophysical Notes 120
Measurements 123
Power/Head Characteristics 123
K. FINILE STREAM 125
Measurements 128
Power/Head Characteristics 128
L. OTHER DRAINAGE AREAS AND SPRINGS 128
M. SPRINGS 129
NOTES FOR CHAPTER IV 131
V. EXISTING WATER FACILITIES 134
A. IMPOUNDMENT AREAS 137
1. Asan Springs 137
Hydro Power Potential 138
2. Santa Rita Springs 138
Hydro Power Potential 138
3. Geus Dam 139
Hydro Power Potential 139
4. Fena Reservoir 140
B. WATER DISTRIBUTION FACILITIES 141
NOTES FOR CHAPTER V 143

Chapter Page

VI. FURTHER ECONOMIC CONSIDERATIONS 144
A. WATER SALES 145
B. COST OF ENERGY 147
C. TAX INCENTIVES 148
D. LONG-RANGE IMPACT OF HYDROELECTRICAL
DEVELOPMENT 149
NOTES FOR CHAPTER VI 150
VII. CONCLUSIONS AND RECOMMENDATIONS 151
NOTES FOR CHAPTER VII 155
BIBLIOGRAPHY 156

LIST OF TABLES

Table Page

3-1 Summary of Rainfall at Agana Naval Air Station,

Guam, 1952-1962 42

3-2 Precipitation Stations on Guam 43

3-3 Rocks of Guam and Their Water-Bearing Properties 46

3-4 Recording Stream-Guaging Stations on Guam 55

3-5 Summary of Streamflow Statistics 56

LIST OF FIGURES

Figure Page

2-1 Canal or Dam with New Penstock

Concrete Dam with Existing Conduit

Earth Dam with Existing Outlet Works 19

2-2 Minimum Civil-Feature Costs

Maximum Civil-Feature Costs 21

3-1 Approximate Distribution of Mean Annual Rainfall

in inches 44

3-2 Physiographic Divisions of Guam 50

3-3 Land Use Map 51

3-4 Vicinity Map 52

3-5 Stream Guaging Station Locations 53

4-1 Key to Drainage Area Maps 62

4-2 Pago Drainage System 66

4-3 Duration Discharge Curve for Pago River 67

4-4 Duration Discharge Curve for Lonfit River 68

4-5 Ylig River Drainage Area 72

4-6 Duration Discharge Curve for Ylig River 73

4-7 Talofofo Drainage Area 77

4-8 Duration Discharge Curve for Talofofo (Maagas) 78

4-9 Duration Discharge Curve for Tolaeyuus River 79

4-10 Duration Discharge Curve for Imong River 80

Figure Page

4-11 Duration Discharge Curve for Fena Dam 81
4-12 Duration Discharge Curve for Almagosa Springs 82
4-13 Ugum River Drainage Area 88
4-14 Duration Discharge Curve for Ugum River 89
4-15 Duration Discharge Curve for Ugum River(b) 90

4-16 Pauliluc River Drainage Area 96

4-17 Duration Discharge Curve for Pauliluc River 97

4-18 Inarajan River Drainage Area 101

4-19 Duration Discharge Curve for Inarajan River 102

4-20 Geus River Drainage Area 107

4-21 Duration Discharge Curve for Geus River 108

4-22 Umatac River Drainage Area ill

4-23 Duration Discharge Curve for Umatac River 112

4-24 La Sa Fua River Drainage Area 116

4-25 Duration Discharge Curve for La Sa Fua River 117

4-26 Cetti River Drainage Area 121

4-27 Duration Discharge Curve for Cetti River 122

4-28 Finile River Drainage Area 126

4-29 Duration Discharge Curve for Finile River 127

I
I
I
I
I
I
I
I
I Chapter I
I
I
I
I
I
I
I
I
I
I

I. INTRODUCTION

A. PURPOSE OF STUDY

The purpose of this study is to address Guam's

potential for hydroelectric development, and particularly the

economic and environmental impacts of hydro generation

facilities at existing and proposed water improvement

structures associated with the main rivers of Southern Guam.

The study will explore the potential of the proposed Ugum

River Dam site, along with alternative sites, for

hydroelectric developments in sizes ranging from 5 MW down to

small farm or home use.

Information obtained from this study will assist the

Guam Energy Office and the Bureau of Planning's Guam Coastal

Management Program in further assessment of renewable,

nonpolluting alternative energy resources. It will also be of

value to the decision-making process regarding the location of

proposed dam sites on Guam's rivers.

B. CENTRAL ENERGY IMPACT PROGRAM

In order to "provide grants and credit assistance to

the Coastal states and communities to help them deal with the

impacts of coastal energy development," the Coastal Energy

Impact Program (CEIP) was created, on June 26, 1976.

Guam qualified for assistance in the program and was

funded under section 308(c) of the Coastal Zone Management Act

of which CEIP is a part. This study was funded for the
purpose of "Studying the Consequences of Energy Facilities."

Such grants shall be used for the study of, and
planning for, any economic, social, or
environmental consequences which has occurred,
is occurring, or is likely to occur as a result
of the siting, construction, expansion or
operation of such new or expanded energy
facilities. [Sec. 308(c) CZMAI

C. BACKGROUND

Historically, the U. S. has emphasized the development
of large hydro sites, those over 15 MW. The smaller sites,
lacking the advantage of benefits of economy of scale, and low
long term operating costs, remained undeveloped. 1
The current push toward alternate energy generation
systems combined with problems associated with larger
installations - high initial investments, legal environmental
licensing impasses, lengthy planning, design and construction
periods - has effected a renewed interest in smaller unit
development.2
Hydro development is attractive for several reasons. It
is a form of energy that is controlled easily, and is converted
to work at an extremely high efficiency. Compared to solar,

chemical and thermal efficiencies of 29 - 45%, hydro systems

run 80 - 90% efficicient. If the source water is

uncontaminated, it is pollution-free, does not produce waste

residuals and consequently is an extremely "pure" form @of

energy. Because the work application can be readily matched to

the potentials of the source, the complete range of available

flow volumes can be used on Guam - from small streams to the
largest rivers. 3

Hydro generation is not "new" technology, but, rather,

11proven" technology. Simply, the amount of energy available at

a given location is a function of the quantity of water

available, the vertical distance the water falls and the
efficiency of the power plant. 4

D. LIMITING FACTORS

The primary limiting factor on Guam for hydro

development is the small flow volume of Guam's streams and

rivers. Hydroelectric sites around the world are located on

rivers many times larger than the largest river on Guam. For

example, the Tucurui River in Brazil is presently being dammed

for hydroelectric generat ion development. The plant is being

designed to use a flow of 1.8 million cubic feet per second

(CFS), and will have a capacity of 4,000 MW (Guam's peak demand

is 150 MW).

By comparison, the largest average flow on Guam's rivers

(the Talofofo River) about 50 CFS. This means that the largest

hydro plant on Guam would still be a small installation by

world-wide standards.

Contributing to the problem, storm activity and dry

seasons effect radical changes in the flow of the waters on
Guam, causing, alternately, flood and drought situations. This
creates design and operation problems for hydro plants which

utilize steady, year-round flows.
Although Guam's rivers have sections that fall several
hundred vertical feet, these sections; are generally the upper

reaches of the rivers where the flow is small. In periods of

heavy rains, waterfalls of limited flow volume are seen
throughout the southern area of Guam. ' Some of these exceed 100
foot drops, but are of extremely limited duration, and/or are

located in areas of limited access.

Access is a very important factor. Since the projected
scale of local hydro development is small, the cost of civil
works - roads, dams, piping - need to be minimized for a site

to be cost effective. Since the cheapest access or maintenance
roads currently cost approximately $25.00 per running foot
(over $130,000.00 per mile), a prospective site would have to
have an existing access road at, or nearby, the prospective

site.

Another limiting factor for hydro design is local stream

f I ow data. At this time, comprehensive flow data relative to

hydro development is not available. Because of the great
variability in natural stream flows, a hydrologic record that
is as long as possible is needed in order to analyze any site's
potential energy output. This record should include a
representative sample of high-flow and low-flow years and

should cover any critical dry period. For most cases, a period

of 20 to 25 years is prefered. A shorter record, such as 8 to
10 years, is barely adequate, and on Guam is usually all that

is available.

Locally, the major rivers and streams are guaged but at
only one or two locations, usually near the estuary. Upstream
data is scarce and neccessitate flow estimates which limit the

accuracy of projected power potential.

E. LEGAL ISSUES

In addition to the above limiting factors, another
potential roadblock to extensive hydroelectric development is
the regulatory process. Although this is not a part of this
study, it should be mentioned now and studied in depth in a
subsequent study. There are numerous federal regulatory laws
to which Stateside hydro projects must conform along with the
various Federal, state, and local agencies that have to be
contacted for licensing a hydro plant. Originally, statutes
were designed to serve specific purposes, but have accumulated
and combine to form an overlapping and conflicting authority
over hydro development in the Mainland. The list is as
follows:5

1. Federal Regulatory Acts Affecting Hydro Development:

a. Federal Power Act

b. National Environmental Policy Act

c. Fish & Wildlife Coordination Act

d. Historical Preservation Act

e. Water Pollution Control Act

f. Wild & Scenic Rivers Act.

g. Endangered Species Act

h. Federal Land Policy and Management Act

i. Water Quality Improvement Act

j. Coastal Zone Management Act

k. Public Utility Regulatory & Pol icies Act

1. National Wilderness Preservaton Act

2. Federal Agencies to Contact in FERC Prelicensing

Process

a. U. S. Fish & Wildlife Service

b. Environmental Protection Agency

c. River Basin Commission

d. U. S. Army Corps of Engineers

e. National Marine Fisheries Service

f. Department of the Interior Environmental Division

g. Department of the Interior Heritage Conservation

& Recreation Service

3. State Agencies - include those with responsibility

for:

a. Dam Safety

b. Energy Development, Planning, and Research

c. Fish & Wildlife Preservation

d. Flood Control

e. Historical Preservation

f. Quality Control

g. Water Rights and Resources

h. In addtion, in some states the Public Utilities

Commission must be contacted.

4. Local Agencies - include those with responsibility

for:

a. Zoning

b. Property Acquisition

c. Taxation

At the end of 1980 the Federal Energy Regulatory

Commission (FFRC) approved exemptions for small hydro projects

those which develop a generating capacity of less than 5 MW

aggregate and use an existing dam or natural water feature,

such as a diversion with no impoundment. Although this

exemption gives preference to project owners where the project

involves only non-Federal land, it also permits exemptions for

projects located totally or partly on Federal soil. Another

feature to the legislation is the automatic action clause,

which mandates automatic action on exemption applications, 120

days after filing.6

F. STUDY GOALS

1. Describe the Study Area

2. Examine Five Possible Hydro Development Scenarios:

a. Plant at existing impoundment areas

b. Plant at proposed impoundment areas

c. Plant at existing distribution system

d. Plant at undeveloped site

e. Small scale site development

3. Describe the Hyrological Characteristics of the

Major Rivers, Streams, and Springs In the Study Area
4. Describe the Head and Power Potential of the Major
Rivers, Streams, and Springs In the Study Area

5. Rank Existing and Prospective Sites as to Their

Potential for Hydro Development
6. Produce Map of Major Rivers, Streams, and Springs,
Using Color-Coding to Indicate Relative Average

Annual Flow Volumes

G. STUDY METHODOLOGY

The first phase of this study was the collection and

analysis of practical literature. Pursuant to this literature

search, the author visited the local offices of the U. S.

Geological Survey, the U. S. Army Corps of Engineers, the Guam
Environmental Protection Agency, the Bureau of Planning, the

Guam Energy Office, and the Public Utility Agency of Guam. The

reports and information obtained from these agencies, and used

for this report, are listed in the Bibliography.

The second phase of this study was the description of

scenarios of hydro development. Based on standard hydro

construction cost, five sets of hydro strategies were examined

and discussed. These strategies are:

1. Plant at Existing Impoundment Area

2. Plant at Proposed Impoundment Area

3. Plant at Existing Distribution System

4. Plant at Undeveloped Site

5. Small Scale Site Development

Factors affecting the prioritizing include net

generation potential, development cost, use points of services,

and environmental impacts.

The next phase of the study was Inventory Assessment.

The existing water facilities were examined, and their physical

condition, capacity for hydro potential, and location relative

to nearby use points were noted.

Then, the author studied the 32 major drainage basins of

Southern and Central Guam. Each drainage basin was isolated,

and on each isolation map existing data were recorded. Known

guaging stations and the average measurements were recorded on

maps which already contained contour markings showing

elevation. Sites were checked for head/flow, combinations, and

those potential combination points were rechecked on larger

maps to determine nearness to infrastructure and possible use

points. Flume and penstock lengths required to optimize

head/flow combinations were sketched onto the maps on areas

which lacked naturally existing high head/flow combination

points. A power projection program was developed to quickly

project potential hydroelectric generated power at any

location. This program was used to target sites with the best

combination of data. These sites were recorded, to be later

ranked in terms of development potential.

The author then investigated the hydro potential at the

Proposed Ugum River and drainage River Dam sites, using the

data developed by the U. S. Army Corps of Engineers. The hydro

potential at the sites were calculated considering a varity of
flow conditions ranging from the lowest projected dam run-off

to the total discharge presently targeted to be used for

farming and irrigation.

The final part of this phase uses the solicitation of

current equipment notes and price quotes for the components of

the hydro plant from off-island companies ranging in location
from Japan and the United States Mainland to European

manufacturers. These notes and price quotes are incorporated

into the report and support the cost benefit calculations used

to develop the economic sections contained herein.

The fourth phase of the study was the discussion of

relevant economic considerations. In this phase the impact of

water sales and rising cost of conventional energy versus

alternative energy development are addressed.

The final phase is the development of conclusions and

recommendations.

H. SCOPE OF STUDY

Guam, similar to many other geographic locations, is
faced with an energy/environmental trade-off situation. Local

and national policies mandate action to limit negative

environmental impacts in construction, and in the operation of

public and private enterprises. In the case of energy

enterprises, the environmental aspects are closely tied to and

effect the choice of energy source, its mode of development,

and even its subsequent operation. In hydro generation, the

environmental issues represent limitations mainly in the

initial stages of development. In dam construction, water

body diversions, etc., there are obvious immediate negative

environmental impacts. Regardless of how these are weighed

against the long range impact when compared to conventional

sources of energy, particularly fossil fuel sources, they still

limit the scope of the study.

The following are three statements of local and national

policy that set limits to this study:

Agencies should ... include in the
decision-making process appropriate and careful

consideration of all environmental effects of
proposed actions... [and to] avoid or minimize
adverse effects of proposed actions and restore
or enhance environmental quality as much as
possible....

Fed. Reg. Vol. 40, #72 @16815
Section 6.100 re
National Environmetal Policy
Act of 1969

It is-the public policy of Guam ... that a high
quality environment be maintained at all
times ... and that environmental degradation of
all land, water, and air. . . should not be
allowed. P.L. 11-91
GEPA Enabling Legislation

The national objective of attaining a greater
degree of energy self-sufficiency would be
advanced by providing Federal financial
assistance to meet state and local needs
resulting from new or expanded energy activity
in or on the coastal zone.

CZMA Amendments of 1976
P.L. 94-370
Section 302(i)
Congressional Findings

Another factor that affects the scope of the study is

the amount and quality of flow duration measurements. Some of

the hydro sites, suspected to be better sites, are not guaged

at that particular point. The author was obligated to

estimate stream flow, using U. S. Army Corps of Engineers

methodol ogy, at these sites, resulting in approximate

calculations.

In terms of the number and detail of the site

calculations to be performed, obviously, detailed calculations

for every linear foot of waterway on Guam could not be funded

under this project. One of the functions of this study,
nevertheless, is to appraise hydro potential in more than one
scale and application.

For this reason, the study will address both small and
large scale applications as discussed in the study goals.

I. PREVIOUS INVESTIGATIONS AND PRESENT WORK

Prior to this study, there has been limited
investigation into the hydroelectric generation potential of
Guam. On June 13, 1980, the Guam Energy Office received a
letter from Mr. W.D.C. Murray, representing Engineering &
Power Development Consultants, Ltd., England. Mr. Murray

states in his letter:

... We have found that the [hydroelectric]
potential is disappointingly low; largely
because long downstream reaches of most rivers,
where the flow is greatest, are at low
elevations.

In the upstream areas, where appreciable
changes in level occur, the flows are small ,
and so is the available energy.
Although there are perhaps five sites that
might economically be developed and could
justify their costs in the value of oil saved,
the installed capacity would be too small to
interest other than a private consumer. No
site would have a capacity greater than 150 kW;
obviously insignifigant compared with the
maximum demand on Guam of 150 MW.

This is the only known recorded estimate to date for
hydroelectric generation potential. However, there was no

indication of the methodology used in the formulation of this

estimate.

Pacific Energy Management Consultants, Guam, under the

same CEIP funding source, are presently studying waste water

low-head hydroelectric power systems on Guam.

These in conjunction with this study represent the

total in hydroelectric investigations for Guam.

J. ACKNOWLEDGEMENTS

We would like to acknowledge the pertinent statistical

data supplied by Mr. Charles Huxel, USGS, and Mr. Frank

Dayton, U. S. Amy Corps of Engineers, and the technical

guidance of Mr. Walter F. Pinckert, P.E., of W.F. Pinckert &

Associates.

We further wish to express our sincere appreciation to

Mr. Jay Lather, Director of the Guam Energy Office, who made

this report possible.

NOTES FOR CHAPTER I

1. Leslie M. Price, "Power From Water", Power, April 1980
pp. S.1-S.2

2. Ibid.

3. Ibid.

4. Ibid.

5. Ibid., pp. S.5-S.8

6. IOAHO National Engineering Laboratory, Small Hydro Bulletin
U. S. Department of Energy Report, Yol. 2, No. 4
December, 1980

I
I
I
I
I
I
I
I
I Chapter II
I
I
I
I
I
I
I
I
I
I

II. HYDRO STRATEGIES

A. OVERVIEW

This section describes the typical requirements, costs,
and impacts of hydroelectric development relative to five
implementation strategies. These stragtegies are: development
of a hydro plant at existing impoundment areas; at proposed
impoundment areas; at exi sting distribution systems; at

undeveloped sites, and at small scale sites.

B. BASIC HYDRO REQUIREMENTS

Any scenario of hydro development must address and
include some very basic components. To create a potential for

power, a site must have flowing or accumulating water, that
falls a vertical distance. This fall, however, cannot be open
flow in a flume or over a waterfall. The pressure which
produces the power must be created, either by damming the

water or by transferring it from one elevation to a lower

elevation in a pipe or penstock.
The simplest power plant would be comprised of a pipe
that flows from a high elevation to a lower elevation, a pump
installed in the pipe in reverse flow, a generator to create
electricity from the spinning pump shaft and a means to

distribute the electricity or store it.

This type of power plant has limited applications,

however, and the usual hydro site has more requirements. The
majority of these requirements, and, consequently, the costs
for the hydro plant, go to the civil works, particularly at
potential sites with no existing dam structure. The first
requirement is a dam or reservoir. 2
Dams are classified by their function. A dam designed

to relocate the water for irrigation, or to a power plant, for
instance, is called a diversion dam. Because these dams
provide little or no storage they create little or no head.
Dams that are designed to retain larger bodies of water
which can be used to regulate or augment the river flows in
order to compensate for variances in natural fl ow are
designated storage dams. 3
Generally speaking, storage dams cost more than
diversion dams, because diversion dams entail less
construction. There is no simple "rule of thumb" estimation

for dam cost in hydro applications, since there are many
different types of dams which may be made from different
materials. Relative to the total hydro poject, however, the
dam consumes generally half of the project costs. 4

Intake gate CANAL OR DAM WITH NEW PENS70CK

77-7--@=-

Intake valve Tailrace

CONCRETE DAM WITH EXIST:NG CONDUIT
@W

Intake valve

-ol
Intake E@isling outlet ks
Intake valve,"
FARTH DAM WITH EXISTING OUTLET WORKS

Figure 2-1

Figure 2-1 shows three different dams and outlet trunks

for hydro plant designs. The top figure shows a new penstock
and intake addition to an existing dam or canal. The middle

figure shows a concrete dam, the normal type for Guam, with
existing conduit. The bottom figure is an earth dam with
existing outlet works. 5

On Guam a necessary addition to any dam is a spillway.
The function of a spillway is to divert floods or excess flows

or allow them to pass safely over the dam. Spillway costs are
directly related to the size of the anticipated maximum river

discharge at the dam. Other types of control devices at the

dam include radial gates, drum gates, slide and wheel gates,

flashboards, stoplogs, soldier beams and bulkheads. For any

hydro installation a competent designer must analyze the

stream data and proposed dam site to determine the necessary
dam components. 6

Another basic civil component to a hydro site is the

outlet works. This allows a controlled stream of water to

flow to the powerhouse from the reservoir. This could consist

of a tunnel or a penstock but it must include an entrance

channel, trashracks, an intake structure, a waterway, a water

control system, bypass valves, and any operation or

maintenance tunnels or access shafts.

Regarding penstocks, it should be noted here that in

the analysis of the river power characteristics it was

repeatedly found that because of the relatively low power
output potential of the sites, those which required long

penstocks were not economically justifyable. There are

locations which were investigated, particularly Almagosa

Springs (elevation 640 +/- feet) which have attractive head

potential. Economic problems accompanied these development

scenarios in the form of costs for penstocks which would

survive the high pressure stresses while not losing

substantial head due to reduced pipe diameter. Several pipe

diameters were considered and their loss in head calculated.

The result was disapointing. Even a 12" pipe loses about 65
feet of head per running mile, while costing as much as $40-00

to $50.00 per linear foot to lay on the ground surface.

Smaller diameters are less costly but 1 ose more head,

defeating the purpose of developing high head sources, which

require miles of penstock.

The final civil component to any construction site is

an access road. There must be access to the site in the form

of a road capable of transporting equipment, tools, and

persons. At a cost of about $25.00 per linear foot or

$132,000.00 per mile, this is another component that can
financially make or break a small hydro project. 7

C. HYDRO SCENARIOS

1. Plant at Existing Impoundment Area

Figure 2-2 shows two pie graphs depicting maximum and

minimum civil-feature costs. The minimum civil feature graph

is for projects having existing outlet works, which require

limited penstock and other waterway-passage costs. . The other

graph indicates projects with major outlet works requirements

such as long penstocks or major alteration of existing outlet
works. 8

Civil features
Turbinel Mechanical 45%
generator electrical
Civil 39% 55% Turbi Mechanical
electrical
features Engineering generator 25%
15% A and I egal 18%
Engineering indirect 30% 20%
and le at 11% 4% Accessory
9 10% electrical
indirect 30% 20% Accessofy equipment
70% % electrical Wefest during
M.
OP e h
Cc @A"
Eng n ;ng
an le
20%

A
ing
e
e, a
quipment construction Misc power
'ng
In lefest during plant equipment
o Aksc power 3%
corwtuction
plant equipment MAXIMUM CiViL-FEATURES COSTS
MINIMUM CIVIL-FEATURES COSTS
Figure 2-2

Unfortunately, there is no standard package for adding

a small hydroelectric plant to an existing dam or for even

designing a new site. The type of dalm, the site data, the dam

function, the type of outlet works required, the nearest

1 ocati on for an el ectri c power grid, all shape design
decisions and affect construction costs. 9

using an existing impoundment area can radically cut

costs as well as other design concepts such as:

a. Using all reliable and useful parts of the existing

structure;

b. Avoiding limiting the use of coffer dams and

bulkheads or other temporary structures;

C. Increa sing the available head and corresponding

power potential by using collapsable flashboards and

gates;

d. Eliminating, where possible, buildings designed only

for water production. One must be careful here,

because many of the Public Utility Agency of Guam

equipment installations are suffering from

deterioration, due to exposure to local elements.

Environmental impact. The degree to which the hydroelectric

installation will affect the surrounding environment depends

on the plant's site, its design, the way it is operated, and
the way it is constructed. 10

By installing a plant at an existing dam, environmental

difficulties can be kept to a minimum. Dam construction

constitutes the major negative environmental impact and at an

existing dam the surrounding flora and fauna have already

adjusted to the major changes. Since no major excavation is

required, there are no problems relative to damaging

historical or archeological sites. The environmental stress

during construction is limited to the minor, temporary

disturbances that happen while the plant is being installed,

and to the visual infringement of the transmission lines
required for power distribution. 11

Negative impact could result after completion of the
power plant if the flow-release patterns radically affected

the upstream water levels to the extent that it interfered
with the fish and wildlife habitats. 12

Potential sites. Four major impoundment areas are addressed

in this study. These are Asan Spring Basins, Santa Rita

Spring Basins, Geus River Dam, and Fena Valley Reservoir. Of
these, the only potentially developable site is the Fena Dam,
which is addressed thoroughly in Chapter V, Existing Water
Facilities; Section A., Impoundment Areas.

2. Plant at Proposed Site

There are seven proposed sites for development of
surface water storage. These are located in the following
drainage areas:

a. Ugum River

b. Inarajan River

c. Umatac River

d. La Sa Fua River

e. Talofofo River

f. Finile River

9. Agana and Janum Springs

The recommended points of development are shown on the

drainage area maps included in this study, complete with their

coordinates in meters.

These locations could cut hydro installation costs in

the same ways mentioned in the previous discussion, "Plant at

Existing Impoundment Area."

The priority of development is ranked in the Surface

Water Survey by Austin Smith and Associates, Inc., June
1968. 13 The following prioritization schedule comes from

that report and is included below:

Priority No. 1

The first new surface Water source to be
developed should be the Ugum River above
Talofofo Falls. This source, when fully
developed, is of sufficient size to provide
all supply requirements of the Southern and
East Coast demands through 1995. The Ugum
development can be the primary source for
the villages of Yona, Talofofo, and
Inarajan, and can also provide the alternate
source for Merizo and Umatac when the
distribution systems are extended to these
villages. Any surplus available over and
above the requirements of the villages can
be transferred through the 12 inch
Yona-Chalan Paigo transmission pipeline of
the FY67 Water System Improvements Program

to the Central Area System.

Priority No. 2

The second source development under
discussion in this report should be that of
Agana Spring. Upon the completion of the
FY68 Water System Improvements, two one
million gallon reservoirs at Agana Heights
and Tumon could receive this water for
storage and di stri buti on. As these
reservoirs have overflow elevations of 190
feet, some one hundred feet lower than the
reservoirs of the remainder of the central
system, the pumping costs from Agana Spring
to the system will be less per unit pumped
than any other source other than Asan Spring.

As Agana Spring is centrally located, the
development of its source will relieve some
of the draught presently being exerted on
the Dededo well field by the Tumon and
Tamuning areas. It appears that the
development of Agana Spring can be
accomplished by either a battery of wells or
by a central pumping station and treatment
plant. Because of its central location and
the close proximity of both commercial
business establishments and private
residences, the minimum treatment of
chlorination must be considered a
requirement under either form of development.

Priorities No. 3 and No. 4

Depending on the growth pattern and the
population build-up, the third development
should be the Umatac-La Sa Fua Rivers or the
Talofofo River.

If resort areas and residential development
takes place along the western coastline
around Cetti Bay or in the rolling hills
area south of Agat, the Umatac-La Sa Fua
development should be next. This would
provide water for Umatac, the developments
and Agat-Santa Rita through a new water line
along Route 2. During periods of higher
flows some of this water could flow
southward also to Merizo through a future
transmission pipeline.

On the other hand, if developments continue

in the Windward Hills area and along Route
17 north of the Naval reservation, the
Talofofo River development should precede
the Umatac-La Sa Fua improvements.

Priority No. 5

Inarajan River would next be developed to
improve the suipply along the eastern and
southern coastlines. This development
appears to be less desirous than the Ugum
because of the sediments found in the stream
which will require more exacting and
additional treatment. The reason for
development of this source -is not so much to
augment the UgLIM supply for the eastern and
southern shores, but rather to become the
primary supply for this area, thereby
releasing the Ugum River water for further
augmentation of' the central area system as
demands there rise beyond the limits of the
well fields.

It is considered probable that prior to the
year 2000 booster stations will be
transmitting as much as three million
gallons per da,@ northward into Chalan Pago
and Mangilao io improve the supply of the
central system. By that time, the
Barrigada, Chalan Pago, Chaot, Afame and
Dededo wells will be delivering their
supplies to the areas lying north and east
of NAS Agana.

Priority No. 6

Under present population distribution and
expected growth curves, the Janum Spring
development is recommended to be last, not
because of lack of water requirements in the
vicinity, but because of unit costs of
development. The required high lift to the
Yigo plateau and the relative incaccesi-
bility to the spring are the main deterrents
to its immediate or immediate future devel-
opment.

Conditional Priority No. 7

Left to the last for discussion purposes,
but not necessarily last in actual
development, is the Finile Stream and spring
at Agat. This development must and will
remain small because of the relatively

limited supply and the scarcity of water
available during drought seasons. This
source also has its political innuendos,
too. At present, the ample Navy supply
provides water to this area and the
Government of Guam purchases this water
directly from the Navy for distribution.
Should the Territorial Government desire to
divorce itself completely from the Navy,
then this system must be developed to its
fullest, but it must also be augmented from
another source.

It has been our thinking that all Navy
sources to the Territorial Government be
curtailed elsewhere throughout the island
first, leaving this civilian area, which
lies near the Navy source, on the Navy
supply entirely.

Should the Government of Guam wish to phase
its water system off the Navy supply, this
development could proceed immediately,
providing some 300,000 gallons of water to
the civilian population of Agat and Santa
Rita about 75 percent of the year .. A
metered, air break Navy supply that is float
controlled could be provided at some
reservoir site above either Agat or Santa
Rita Villages. When the Finile supply falls
below demand requi rements, the Navy
augmentation supply could flow into the
system.

Later, when the Umatac or Talofofo
developments have been completed, these
sources could then replace the Navy
augmentation.

The timing and development of this source,
therefore, is dependent upon the political
aspects and business arrangements of the
United States Navy and the Territorial
Government of Guam.

These sites were ranked for domestic water supply and

are not necessarily the best sites for hydro generation in

these areas. The Agana and Janum Springs are not potential

hydro sites. All of the other river basins mentioned have

hydro potential at the proposed locations in these areas:

Ugum River. The dam proposed by the U. S. Army Corps
of Engineers will create a potential head of about 100

feet and with the flow and design storage requirements

is the best hydro site on the island. The potential

is discussed further in Chapter IV, The Rivers.

Inarajan River. The dam proposed by the U. S. Army
Corps of Engineers will create a potential head of

about 100 feet. Based on 'this data and the flow

records for the river, this is ranked second among the

potential sites.

The rest of the proposed impoundments lack data

describing the proposed dam and its dimensions. Assumi ng a
dam height of 50 feet the next best sites, in order, would be:

a. Talofofo River

b. Umatac River

c. La Sa Fua River

The Finile stream has a very low discharge and is known
for dry periods. It is therefore a low priority site for

hydro development.
The targeted points of development for the Ugum,

Umatac, and La Sa Fua Rivers lie at high elevations, 200

feet and 300 +/- feet, respectively. In each case the target

location falls on a stretch with a high gradient. This means

that each site has good potential for developing head, even if

the proposed dam lacks substantial height.

It should be noted that should these sites be developed
to augment the domestic water supply of a village then any
potential head at the site will be used to satisfy or defray
the pumping requirements. Consequently, any hydroelectric

generation at these sites would be limited to that which could

be produced by the existing head at the proposed dam using the
discharge designed to maintain stream flow. In the case of

high flow periods, the flow would be boosted by water that

would otherwise have been diverted over the spillway as excess.
Without having more information on the proposed dams on
the Umatac, Talofofo, and La Sa Fua Rivers, it is impossible

to make detailed economic projections relative to the cost

effectiveness or payback period of a hydro plant addition.

Environmental impact. The environmental impacts here are the
same as discussed in' the previous section, "Plant at Existing

Impoundment Area."

3. Plant at Existing Distribution System

In rare cases in the development of a fresh water or

waste water removal system, the situation arises in which a

pipe transmits water or waste from a high elevation to a lower

one, creating a pressure diferential capable of doing work.

This happens at several locations on Guam in the fresh

water systems, but not to the extent to be commercially

devel opabl e.

There is, however, a case presently being studied in

Northern Guam, where waste water is -dropped in a pipe from a

high altitude plateau to sea level, creating a cost effective

hydro site.

This case is COVE!red in detail in the study for the

Guam Energy Office, entitled Waste Water Low-Head Hyroelectric

Power Systems on Guam, conducted by the Pacific Energy

Management Corp., Guam.

Environmental impact. A major bonus of a system like this, is

that it is totally self--contained, and therefore constitutes

no environmental threat.

4. Plant at Undeveloped Site

Obviously, the toughest way to economically justify a

hydro plant is to start at a totally undeveloped site. On

Guam, it is particularly difficult because the average

potential hydro installation is too small to offset the

substantial start-up costs.

To better illustrate this, consider a particular site.

Site 'T' is located on the Imong River, on a stretch that

falls 80 vertical feet over a river length of 4,000 feet. The

average flow in that section is 6.59 mgd and the 90% flow case

is 1.1 mgd. The developable head is 40 feet, using a 1,000

foot penstock, and the planned point of use is one mile from

the site. The nearest access road is one-half mile from the

site.

Cost of development. The first cost incurred must be the

extension of the access road, which costs about $130,000 a

mile. The design plans for half a mile of road at a cost of

$66,000.00.

The design calls for a small diversion dam, at a cost
of $15,000.00 and 1 000 feet of penstock at a cost of
$40,000.00.

Once the plant is generating electricity, it must be
delivered to some use point. This design calls for one mile
of transmission lines at a cost of approximately $144,000.00.
The total cost at this point totals $265,000.00.

A 20 kW plant will cost about $32,000.00 and will

generate about 117,000 kWh in one year. To buy this
electricity at $0.10/kW would cost $11,700.00. Applying this
amount towards a 30 year loan with equal annual payments at
10% interest, one could borrow $110,294.90.
This means the plant is not nearly cost effective, as
designed. However, consider the same case with different

features. First assume the access road runs very near to the
site and only has to be slightly improved at a cost of
$5,000-00. Next the power is to be used at a farm adjacent to

the site. The cost of electrical hookup is $4,000.OD.

Furthermore, the designer chose a good natural spot that

develops 20 feet or half of the head with a minimum length of
penstock, say 80 feet, al: a cost of $3,200.00. He choses to
intall a 10 kW plant that will cost $25,000.00 and will

generate 58,500 kWh in a Year. Add to this 10% for design and
legal fees -. the unit is a prepackaged unit, the site is

small, and he does not encounter much environmental resistance
or legal problems. His -total costs are now $57,420.00. Wi th

the same financing constraints, based on the new amount he can

generate, his borrowing power is $55:,147.45. Should the cost

of energy rise at all, the site is cost effective.

This scenario shows the impact of the costs of the

civil works features. Note that a diversion dam was used in

this case, not a more expensive storage dam. Independent of

the dam, the potential Undeveloped site's cost effectiveness

is not limited to the amount of power it can produce. The

civil works features, due to their high relative expense, MLISt

be kept to a minimum for a site to have a financial prayer.

The author has taken this a step further by analyzing
the possibility of diverting and combining river branches to
increase flow and thereby increase power potential. Several

river basins such as the Talyfac River, Cetti River and

Inarajan River have configurations similar to that shown in

figure 2-3 in two to four of their branches.

V-DRAINAGE AREA
BOUNDARY

Cl)

R.
@
Ey@
Ey@ I?

'100

)< cl, ve rs 161J J am 30 10

Figure 2-3

In each case calculations were made to estimate the cost of

constructing diversion dams at points A, B, C, and D to divert

the stream flow via flumes and penstocks to form one main body

of higher flow.

In every case the cost of combining the flows far

exceeded the benefit of increased power potential.

Environmental impact. The degree of environmental impact

caused by the construction of a hydro site is directly related

to its size. The construction of a small scale home or farm

plant would have no more negative impact than the installation

of a Public Utility Agency of Guam domestic water station.

Larger sites require more land to be razed and inundated.

Reservoirs and dams produce permanent alterations to the land

and stream. The effect is not as great in populated areas

that made the adjustment long ago. However, in pristine areas

on Guam (Ugum), specimens, of rare plants would be eliminated

due to the impacts of construction, although no species would
be totally eradicated. 14

Another major environmental impact would be the removal

of upstream breeding grounds for most diadromous fishes,

crustaceans, and limpets on Guam. This effect would be
gradual and subtle. 15

A typical dam construction would also create problems

of turbidity, erosion, and increased levels of airborn

hydrocarbons and dust. Clearing and grubbing of surface

vegitation in the construction process also increases the
likelihood of accidental fire and consequent air pollution. 16

Impounding the water creates its own problems.

Spawning-in-stream fauna is influenced by stream discharge

volume, flow duration, and seasonality, all of which would be

changed by the impoundment of water in a reservoir. The

release of the water will have different temperature, oxygen

content, pH and sediment content from the orginal
conditions. 17

A final impact is the potenti al distruction of

archeological sites or artifacts in the impoundment area-18

5. Small Scale Sites

In terms of hydro generation capacity a small scale

application is considered to be less than 10 M Since there

are no existing hydro sites of this size that may be

renovated, new sites at houses and farms would have to be

started without the cost benefits of an existing usable

structure. As indicated in the previous discussions, the

conditions have to be optimal for a new site to be cost

effective.

First, the home or farm owner must live adjacent to a

water body with the head/flow combination necessary to support
the installation. In the Chapter IV, The Rivers, many

stretches are mentioned that have the characteristics for this

size range.

Second, near to the prospective point of use, there

must be a suitable impoundment area. The area must be

examined by a soils expert, otherwise thousands of dollars

would be spent on a dam that leaks.

Third, the plant must be able to develop adequate head
with minimal lengths of penstock (generally less than 100 feet

in length).

Fourth, there must be a road in the immediate vicinity
of the site, to deliver the equipment and construction

materials.

In the case of a farm application, off season labor can
be used for the plant and dam construction, thus cutting costs.
In terms of power plant costs, a 5 kW self-contained
hydro plant costs about $23,000.00 to buy and ship to Guam,
and a 10 kW plant about $25,000.00. If an owner wishes to
have this system payback in 20 years at today's electrical
costs, he must be able to install the plant and pay for all of

the civil works for under $64,000.00., To be abl e to pay the

loan that would provide this amount, his plant must generate

43,800 kWh in a year for 20 years.

NOTES FOR CHAPTER II

1. Leslie M. Price, "Power From Water"S Power, April 1980
PP.S.5-S.11

2. Ibid.

3. Ibid.

4. Ibid.

5. Ibid.

6. Ibid.

7. Ibid.

8. Ibid.

9. Ibid.

10. Ibid.

11. Ibid.

12. Ibid.

13. Austin Smith & Associates, Inc., A Report Covering the
@urface Water Survey of the Island of
Public Utility Agency of Guam Report, T-g-ana, Guam,
June, 1968, pp. 49-51

14. U. S. Army Corps of Engineers, Ugum River Interim Report
and Environmental impact @;Taffement, Harbors and
Rivers, Territory of Guam
U. S. Army Corps of Engineers Report, Fort Shafter,
Hawaii, January 1979, pp.25-27

15. Ibid.

16. Ibid.

17. Ibid.

18. Ibid.

I
I
I
I
I
I
I
I
I Chapter III
I
I
I
I
I
I
I
I
I
I

III. DESCRIPTION OF THE STUDY AREA AND ITS RESOURCES

A. THE STUDY AREA

The following is a section from the Hydrology of Guam by
Porter E. Ward, Stuart H. Hoffard, and Dan A. Davis (1965), 1
which thoroughly describes the topography, climate, and geology
of Guam as it relates to hydrography.

1. TOPOGRAPHY

The northern half of Guam is a gently
undulating limestone plateau bordered by steep
wave-cut cliffs. The plateau slopes generally
southwestward from altitudes of approximately
600 feet in the north to less than 100 feet at
the narrow midsection of the island. The
generally uniform suface is interrupted by
three hills - Barrigada Hill (655 ft.), which
is a broad limestone dome, and Mont Santa Rosa
(858 ft.), and Mataguac Hill (630 ft.), which
are composed of volcanic rock.
No perrenial streams exist on the plateau
because of the high permeability of the
limestone. Water may flow in short channels in
the limestone during heavy rains, but it soon
disappears into numerous sink holes and
fissures. Local runoff has eroded gullies in
the volcanic rock of Mont Santa Rosa and
Mataguac Hill, but here also the water sinks
rapidly into the limestone that sorrounds the
hills.
The southern half of Guam is a rugged,
deeply dissected upland underlain chiefly by
volcanic rock. The surface is deeply channeled
by numerous streams and eroded into peaks,
knobs, ridges, and basins. A nearly continuous
mountain ridge, running from the highland south
of Piti to the southern tip of the island, lies
parallel with and 1-2 miles inland from the

western coast. Several peaks in the ridge are
1,000 feet or more! above sea level, the highest
of which is Mount Lamlam, 1,334 feet above sea
level. Along a part of the western coast an
emerged limestone plain 200-300 feet above sea
level and a little less than a mile wide lies
between the ridge and the shore. Two
projections of the limestone plain form Cabras
Island and Orote Point at Apra Harbor. The
relatively wide and gentle eastern slope of the
mountain ridge merges near -the coast with a
narrow emerged limestone plateau that stands
100-350 feet above sea level and extends from
Pago Bay south.

2. CLIMATE

The description of the climate of Guam is
based largely on a study made by Blumenstock
(1959).
Guam is warm and humid. The mean annual
temperature near sea level is about 81OF;
monthly means range from about 800 in January
to 82 1/20 in June, and recorded extremes
range from 640 in February to 1000, also in
February. The relative humidity ranges from 66
percent in the early afternoon to 89 percent in
the early morning.
Easterly trade winds are dominant throughout
the year, and they blow 90 percent of the time
from January through May. Calms are rare from
January through Play and are frequent from June
through October. Trade-wind speeds generally
are between 4 and 12 mph (miles per hour) and
rarely exceed 24 mph, but typhoons passing over
or near the island may bring winds having
speeds greater than 100 mph.
Guam has two distinct seasons - a dry season
from January through May and a wet season from
July through November. December and June are
transitional, or from year to year they may
fall in either the wet season or the dry
season. The mean annual rainfall ranges from
about 80 inches on the coastal lowlands in the
Apra Harbor areet to about '100 inches on the
uplands in southern Guam (fig. 2)[see fig.
3-11. The isohyetal lines in figure 2 [see
fig. 3-11 indicate somewhat 'less rainfall than
was estimated by Blumenstock (1959, p. 15, fig.
4)[see table 3-21 and reported by Tracey and
others (1964, p. A9). The difference is due to

TABLE 3-1. SUMMARY OF RAINFALL AT AGANA NAVAL AIR STATION, GUAM, 1952-62
JANUARY FEBRUARY IMARCH JAPRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER ANNUAL

AVERAGE 3.85 2.73 1.90 2.87 3.68 4.48 9.10 12.68 14.71 13.06 10.18 5.46 84.70

MAXIMUM 8.07 9.53 4.06 7.35 6.09 9.38 18.03 23.49 18.93 26.48 13.75 8.25 112.76 C\i

MINIMUM 1.34 .31 .58 .66 .66 1.20 4.74 7.37 9.82 9.36 6.78 2.14 63.57

MEDIAN 2.53 2.10 1.78 2.45 2.91 4.48 7.47 11.58 15.14 11.29 10.32 5.14 84.71

TABLE 3-2
PRECIPITATION STATIONS ON GUAM

COMPLETE
GEOGRAPHIC COORDINATES PERIOD OF RECORD YEARS OF MEAN ANNUAL
LATITUDE LONGITUDE RECORDING NON-RECORDING RECORD PRECIPITATION
(Degrees & (Degrees & (Inches)
Minutes) Minutes)

Andersen Air Force Base 13-34 144056 1947-77 27 90.51

Guam Naval Air Station 13-29 144-48 1956-77 19 88.19

U.S. Weather Station 13-33 144-50 1956-77 21 102.36

Mangilao 13-27 144-49 1973-77 4 101.03

Sumay 13-24 144-38 1905-40 33 88.45

Almagosa Springs 13-21 144-42 1952074 20 107.09

Fena Dam 13-22 144-42 1942-73 20 91.97

Fena Filter Plant 13-22 144-42 1954-76 22 96.11

Inarajan (NASA Dan Dan) 13-17 144-44 1952-71 15 93.40

ylig 13-24 144-45 1952-75 22 89.81

Imong 13-20 144-42 1963-73 7 81.05

= = M M = = M M M = M = M M = = M M =

periods of record longer than those available
at the time of Blumenstock's analysis. Of the
total rainfall, 15-20 percent falls during the
d ry season, 68-73 percent during the wet
season, and the remainder during the two
transitional months. Dry-season rainfall is
mostly from scattered light showers. During
the wet season, about a third of the rainy days
have prolongued and steady rain.

?_ ?MILES

EXPLANATION
_80-
90 Isohyet
P-;rV p@ ip4o6on, ;n ;mhes

100

Figure 3-1

The heaviest prolonged rainfall on Guam is
during the passing of typhoons. The greatest
rainfall recorded during a 24-hour period in
.postwar years occurred during Typhoon Alice on
October 14-15, 1953, when 24.90 inches fell at
Anderson Air Force Base and 15.80 inches at the
Agana Naval Air Station. The median of the
.rainfall at 12 widely scattered stations during
the 5-day period of rainfall associated with
I

the typhoon was about 24 inches.
Drought is common on Guam, and severe

drought is not unusual. A drought of several
weeks duration may occur at any time between
.the first of December and the end of May, but
the period of most frequent drought is February
through April. According to Ellumenstock (1959,
p. 29), any month with less than 4 inches of
rain may be cal 1 ed a drought month, and
February through April may be expected to be
drought months in all parts of the island in 3
out of 4 years. A summary of the rainfall at
Agana Naval Air Station (table 1)[see table
3-11 indicates the variation that occurred in
the period 1952-1962.

3. GEOLOGY

The stratigraphy, structure, and pertology
of Guam are described in detail by Tracey and
others (1963), Stark (1963) and Schlanger
(1964) and the summary given here is concerned
mainly with elements of the geology that affect
the hydrology of 'the island. The stratigraphic
units, their distribution, and water-bearing
properties are described briefly in table
2.[see table 3-31
The principal rock in the plateau of
northern Guam is -the Barrigada Limestone, which
lies unconformably on an irregular surface
eroded in volcanic rock of the Alutom Formation
and is overlain by a veneer of the Mariana
Limestone. The base of the Barrigada under
most of the plateau is below sea level. The
volcanic rock extends above sea level in an
area of several square miles near the northern
end of the island and projects through the
limestone at Mont Santa Rosa and Mataguac Hill
(pl. 1)[not shown]. Most of the limestone in
the plateau contains numerous caverns,
fissures, and other solution openings, which
give the rock a high overall permeability. The
volcanic rock has a low permeability.
The Agana Argillaceous Member of the Mariana
Limestone underlies an area of several square
miles in the southern part of the plateau at
the narrow part of the island. It extends
below sea level in the nay-row part of the
island and rests on a steep surface of volcanic
rock dipping northward near the southwestern
boundary of the outcrop, which runs from Pago
Bay to Adelupe Point. The argillaceous
limestone has moderate to high permeability.
The Barrigada Limestone and the

TABLE 3-3. ROCKS OF GUAM AND THEIR WATER-BEARING PROPERTIES

GEOLOGIC FORMATION GENERAL CHARACTER AND DISTRIBUTION WATER-BEARING PROPERTIES

Beach Unconsolidated calcareous sand and Sand and gravel have moderate to
Deposits gravel; consolidated beachrock in high permeability and, below sea
intertidal zone. Occurs irregularly level, are saturated, mostly with
along the shore, particularly in brackish water but locally with
beaches in embayments. small quantities of fresh water.
Pleistocene
and Recent
Alluvium Poorly sorted clay, silt, sand and Most of the material is saturated
small amounts of gravel occur chief- with water a few feet below the
ly in the bottoms of valleys, and ground service, but because of low
muck and cl.ay are in marshy estua- permeability it does not release
rine deposits along the west coast. water readily. Water is fresh ex-
Maximum thickness is about 100 ft. cept at the shore.

Piliocene Mariana A complex of reef and lagoonal lime- Permeability of nonargillaceous
and Limestone stone consisting of a forereef facies, limestone is generally very high
Pleistocene a reef facies, a detrital facies, a but irregular. Where the rock ex-
molluscan facies, and the Agana Argil- tends below sea level, it commonly
laceous Member. Underlies most of the contains relatively fresh basal
north half of Guam; forms a broad mar- ground water, but numerous solution
ginal apron along the east coast be- channels and fissures may promote
tween Pago Bay and Inarajan; and forms sea-water intrusion in some places,
Orote Peninsula. Agana Argillaceious especially in coastal areas.
Member underlies the narrow waist of Permeability of the argillaceous
the island and is dominant in theapron member is moderate to high.
along the east coast. Maximum thick-
ness is greater than 500 ft.

GEOLOGIC FORMATION GENERAL CHARACTER AND DISTRIBUTION WATER-BEARING PROPERTIES

Alifan Generally massive, poorly to well- Permeability is moderate to high.
Limestone consolidated detrital limestone, Contains perched ground water in
recrystallized in some places. Forms some places in southern Guam where
caps on Barrigada Hill, Nimitz Hill, it lies on less permeable volcanic
and the high ridge between Mount rock. Is the source of several
Alifan and Mount Lamlam, and crops perennial springs. Talisay Member
out in small patches along the coast has low permeability, but clayey
in the Apra Harbor area. Includes limestone yields water at small
Talisay Member, at base made up of and mostly intermittent springs.
volcanic conglomerate, bedded marine
clay, marl, and clayey limestone.
Maximum thickness of formation is
about 200 ft.

Janum Well bedded tuffaceous limestone. Permeability low to moderately high,
Late Miocene Formation Small lenticular deposits crop out but does not contain water.
and Pliocene in several localities along the north-
east coast between Lujuna Point and
Anao Point. Maximum thickness is
about 70 ft.

Barrigada Pure detrital limestone, fine grained Permeability of the rock is high.
Limestone and homogeneous, massive, and well Wherever it extends below sea level,
lithified to friable. Underlies most it contains fresh basal ground water
of north half of Guam and crops out as much as 7 ft. above sea level.
over a broad ring-shaped area innorth- This rock supplies numerous wells.
central part. Width of the outcrop
averages about 1 mile. A southern ex-
tension of the outcrop encircles Bar-
rigada Hill. Thickness probably is
greater than 540 ft.

GEOLOGIC FORMATION GENERAL CHARACTER AND DISTRIBUTION WATER-BEARING PROPERTIES

Bonya Friable to compact clayey medium- to Generally high permeability, but
Limestone thick-bedded jointed and fractured because of its small extent it con-
detrital limestone. Exposed princi- tains very little ground water.
pally in small outliers in the Fena-
Talofofo valley, in small patches on
southeast side of Ugum River, in the
Togcha River valley, and near Mount
Santa Rosa. Maximum thickness is
about 120 ft.

Umatac Predominantly a volcanic formation Largely saturated with water below
Formation made up of the following members: depths of a few tens of feet to a
Dandan Flow Member (basalt lava flows); few hundred feet beneath the surface,
Bolanos Pyroclastic Member (breccia, but the rocks are poor water-bearing
conglomerate, sandstone, and shale); materials because of low permeability.
Early Maemong Limestone Member (limestone A surficial mantle of granular wea-
Miocene and calcareous tuff); and Facpi Volca- thered material commonly contains thin 00
nic Member (basalt lava flows, shale, bodies of perched water that discharge
sandstone). Underlies most of Guam at seeps.
lying south of a line between Talofofo
Bay and Agat Bay. Total stratigraphic
thickness is greater than 2,000 ft.
Extends below sea level throughout
area.

GEOLOGIC FORMATION GENERAL CHARACTER AND DISTRIBUTION WATER-BEARING PROPERTIES
Late Alutom Fine- to course-grained well-bedded Permeability is moderate in a few
Eocene and Formation tuffaceous shale and sandstone, len- places but mostly is low. Saturated
Oligocene ses of tuffaceous limestone, and in- with water at variable depths below
terbedded lava flows. Includes the the surface, but yields water slowly
Mahlac Member consisting of thin- to wells. Surficial mantle of wea-
bedded to laminated friable calca- thered material contains small perched
reous shale. The rocks cover a large supplies in many places.
area in central Guam from the vicinity
of Asan and Piti villages to Mount Ju-
mullong Manglo and the northern envi-
rons of the Fena basin. Underlies
younger rock in north half of Guam and
crops out at Mount Santa Rosa and Ma-
taguac Hill. Stratigraphic thickness
greater than 2,000 ft. Extends below
sea level through area.

LEGEND:

FLAT-LYING PLATEAU OF NORTHERN
GUAM AND OROTE PENINSULA
w 4
uj
X -j D'ISSECTED PLATEAU UNDERLAIN BY
:3 CL ARGILLACEOUS LIMESTONE

STEEP DISSECTED SLOPES EAST AND
WEST OF CUESTA SUMMIT

GENTLY SLOPING FOOTHILLS CUT
BY MAJOR STREAMS
DISSECTED LIMESTONE CAP (KARST) 4
ON RIDGETOP IQ

INTERIOR BASIN:
ROLLING LOWLANDS AND KARST 4

COASTAL LOWLANDS AND
ALLUVIAL VALLEY FLOORS
REFERENCE: TRACEY ET AL. 4
GENERAL GEOLOGY OF GUAM

IQ
lb

20
Zl

lb
IQ

lb
IQ
4 2a 2b 1 0 1 2 3 4

MILES

4 IQ
4

FIGURE 3-2
50 PHYSIOGRAPHIC DIVISIONS OF GUAM

LEGEND

URBAN

RURAL

AGRICULTURAL

NAVCAMS WESTPAC
CONSERVATION FINEGAYAN
FAA
ANDERSEN
AF
s
MILITARY LANDS FINEGAYAN
)o

FEDERAL BOUNDARIES

ANDERSEN
SOURCE: LAND USE PLAN HARMON
ANNEX
GUAM 1977-2000, BUREAU
NIONG MONG
OF PLANNING
TOTO 10AITE

AGANA

AGA%A
PEI;@HTS
NATIONAL REGIONA ANDERSEN SOUTH
MEDICAL CENTER NAS AG' NA

NAVCAMS WESTPAC
BARRIGADA
CkN It
A
N1 nrz- NDERSEN BARRIGADA
ANNEX
HILL

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

)NA
APRA
HARBOR
COMPLEX

NAVMAG
AG

MILES

UMATAC
................

INARAJAN

M R:z

FIGURE 3-3

LAND USE MAP

RIIldlon Pt

A.A.F.B.
SOURCE: 208 PLAN FOR Urunc P1. Northwest Field Put I pl.
THE ISLAND OF GUAM

Anderson A.F.B.

Nigo
P H L P P N E S E A

Jonum P1.
Dodedo
7mmon
bo
Ypoo Pt. pagot pt.

Agano, ;
Bay Tomuning
Adelup Pt Ono 11ongrnon
T, 0 Borrigoda
0 Hts.
A in.a Ono maite
-Ij ongi
pitl Ordol holan Pago
-A,,o r
Harbor Zz .
'Pogo Bay
Noval Res.
Yana
P A C F C
Orate
0 C E A N
Yllg Bay
J-f

Agat Bay
. ......... . .
6nf a Rit@ :.7bgchv Bor
Ago
--'--.ITalofofo
Fena,
-:7alofo/o Bay

FOcpI Pt.,:@--.-

So//a oy
COW Bay 1 0 1 2 3 4
M ILES
Lknotac
Llmoloc Bay
n ra an --@norqjv,7 Bay
%

Agfo
TogU0.7 Boy yal) Boy
meri@o

C
oces
Logooly Ajo
ran Boy
/Ai,
FIGURE 3-4
coo Island VICINITY MAP
52

DEDEDO

APRA HARBOR

*AGANA
_@20
8650

PA GO BAY

AGAT SANTA 8580
BAY RITA FENA VALLEY
OAGAT ..8485 RESERVOIR
8083
8450
8481 8500

094
8470
8550
UMA TA C
8096
BAY
UMATAC 8160" 8400

MERIZO 0 8350
8210

L E G E N D

A USGS STREAM GAGING STATION TERRITORY OF GUAM
8550 AND NUMBER

STREAM GAGING STATION
LOCATIONS

nonargillaceous facies of the Mariana are
virtually pure limestone. They are overlain by
a thin friable red soil, which contains
considerable alumina and iron oxide and which
is probably derived from material transported
to the limestone surface. The Agana
Argillaceous Member of the Mariana contains as
much as 6 percent disseminated clay and locally
as much as 50 percent clay in cavities and
fissures. Much of the outcrop area of the
argillaceous limestone is covered by several
feet of clayey soil.
The rocks south of a line between Pago Bay
and Adelupe Point consists mainly of a complex
of pyroclastic rock and lava flows, clastic
sediments derived from the volcanic rock, and
small amount of interbedded limestone, which
make up the Alutom, Umatatac, and Bonya
Formations. Overlying parts of the complex are
beds of the Alifan Limestone forming caps on
peaks and ridges, and the Mariana Limestone
forms marginal aprons along the coast.
The volcanic rock and elastic sediments are
thoroughly weathered to depths of 50 feet or
more over much of the area of exposure. The
upper few feet of the weathered section is
commonly granular and friable. The
permeability of the fresh and weathered rock is
low; the friable mantle is generally a little
more permeable than the underlying material.
The limestone lying on the volcanic and elastic
rock has high permeability.
Unconsolidated deposits of alluvial clay
having some silt, sand, and gravel underlie the
floors of large valleys and form irregular
narrow bands in coastal lowlands along the west
coast. These deposits generally have low
permeability. Moderately to highly permeable
calcareous sand and gravel occur in
discontinuous beach deposits along the shore.

B. HYDROLOGY

Of the nearly billon gallons of water per day that
constitutes Guam's average rainfall, only a quarter flows to

the sea as rivers and streams. Part of the water is lost to

the atmosphere through the process of evaporation and

TABLE 3-5
RECORDING STREAM-GAGING STATIONS ON GUAM

USGS
STATION PERIOD OF DRAINAGE PEAK DISCHARGE OF RECORD
NUMBER STATION NAME LATITUDE LONGITUDE RECORD 1/ AREA DATE DISCHARGE
(Degrees & (Degrees & (Square 7cfs)
Minutes) Minutes) Miles)

8083 Finile Creek 13-23 144-39 1960,77 .28 21 May 76 326
8094 Cetti River 13-19 144-39 1960-67 .75 19 Oct 60 1,420
8096 La Sa Fua River 13-18 144-40 1953-50 1.06 15 Oct 53 1,030
1977
8160 Umatac River 13-18 144-40 1952-76 2.11 19 Oct 60 7,460
8210 Geus River 13-16 144-41 1953-75 .93 19 Oct 60 2,940
LO
8350 Inarajan River 13-17 144-44 1952-77 4.42 11 Oct 63 Not Determined Lo
8400 Tinaga River 13-17 144-45 1952-77 1.89 15 Oct 53 2,980
8450 Tolaeyuus River 13-22 144-43 1951-60 6.54 15 Oct 53 Not Determined
8470 Imong River 13-20 144-42 1960-77 1.95 19 Oct 60 3,370
8481 Almagosa River 13-21 144-42 1972-77 1.32 21 May 76 2,200
8485 Maulap River 13-21 144-42 1972-77 1.15 21 May 76 1,800
8490 Fena Dam Spillway 13-21 144-42 1951-88 5.88 15 Oct 53 Not Determined
8500 Talofofo River 13-21 144-44 1951-62 16.2 15 Oct 53 8,560
8550 Ugum River 13-20 144-45 1952-71 7.13 4Dec 63 7,660
8580 Ylig River 13-23 144-45 1952-77 6.48 9Sep 63 4,900
8620 Lonfit River 13-26 144-45 1951-60 3.11 15 Oct 53 Not Determined
8650 Pago River 13-26 144-45 1951-77 5.67 21 May 76 10,090

1/ Some records are not continuous.

= = M M = M = M M M M = M M M M M M M

TABLE 3- 6
SUMMARY OF STREAMFLOW STATISTICS

USGS DRAINAGE AVERAGE AVERAGE MINIMUM Q Q MAXIMUM
NO. STATION AREA FLOW FLOW FLOW 90 10 FLOW
sq. mi mgd mgd/sq. mi mgd mgd mgd mgd

8083 Finile Creek 0.28 0.92 3.29 0.03 0.13 1.9 211
8094 Cetti River 0.72 2.87 3.99 0.02 0.26 5.7 920
8096 La Sa Fua River 1.06 2.57 2.42 0.11 0.32 4.9 666
8160 Umatac River. 2.11 5.62 2.66 0.07 0.52 11.0 4,820
8210 Geus River 0.95 1.95 2.05 0.00 0.06 3.6 11900
8350 Inarajan River 4.42 11.2 2.53 0.27 1.29 20.0 Not Determined
8400 Tinaga River 1.89 3.68 1.95 0.10 0.26 6.5 1,930
8450 Tolaeyuus River 6.54 13.60 2.08 0.13 0.52 29.7 Not Determined
8470 Imong River 1.95 6.59 3.38 0.24 1.10 12.3 2,180
8500 Talofofo River 16.20 32.9 2.03 0.34 1.16 71.1 5,530
8550 Ugum River 7.13 19.0 2.66 0.71 3.30 40.0 4,950
8580 Ylig River 6.48 18.7 2.89 0.05 0.71 37.5 3,170
8650 Pago River 5.67 16.6 2.93 0.00 0.45 33.0 6,520

transpiration. The rest filters down through the soil and rock

where it accumulates in ground-water reservoirs later appearing

as springs and seeps that combine with streams or directly

discharge into the ocean.

As indicated earlier, there are no streams that flow to

the sea in the northern limestone plateau of Guam. There, the

rainfall is percolated down through the permeable limestone,
replenishing the aquafer and in cases flows to point of

discharge at the shore. In the southern portion, however, the

volcanic terrain does not readily absorb the water, and the

bulk of the rainfall quickly forms rivers and streams that

discharge into the ocean. This runoff averages 250 million
gallons per day (mgd) and comes mostly from streams flowing on
the eastern slope of the island. 2

Beginning in 1950, guaging stations were set up on the

16 major streams to record average and low flow cases.

Additionally, low flow measuring stations have been set up at

40 miscellaneous smaller streams and tributaries. Table

shows thirteen guaging stations, their locations and data

summaries. Individual flow duration curves based on guaging
station recordings accompany the discussion on the individual

streams where data permits.

Because the streamflow in the southern section is a

direct function of the amount of rainfall, the greatest flows
correspond to the wettest months, July to November. During the

transitional months, December and January, records show a
decline in flow, and in the dry months, February to April, the

average flow is only a fraction of that of the rainy months.

C. ENVIRONMENTAL RESOURCES

The environmental resources Df Guam show a range of

manis impact on the island from pristine savanna and ravine

forests to industrial developments. With respect to the

development of hydroelectrical generation plants, the target

area of the southern watersheds have environmental resources

considered to warrent protective planning. These resources

include scenic vistas, cultural resources and archeological

areas, as well as the remaining fragile ravine forests and

savanna ecosystems which are a part of the wetlands, streams

and the erosion-prone watershed 'lands discussed in this
study. 3

Decisions on the use of the land in the study area will

naturally effect trade-offs with the development of the 'land
and water resources on the natural environment. 4

Man's advent, introduction of non-indigenous species,

and habitat modification have altered the terrestrial fauna of
Gujam.5

The terrestrial wildlife presently includes mammmals,

amphibians, lizards, snakes, and crabs, as well as larger

mammals in the savanna and ravine forests, Guam Deer, Carabao,

and feral pig. Formerly plentiful, but now a rare dinner

treat, the Marianas Fruit Bats inhabited the Fena Reservoir
6
area.

In the 1 ocal streams and rivers aquatic wildlife

abounds, and although none are unique to Guam, they include

aholeholes, sleepers, gobies, freshwater shrimp, freshwater

prawns, snails, and freshwater eel. Catfish, tucunare,

mosquito fish, and tilapia are all fish that have been

introduced sucessfully to Guam's reservoirs and streams. A

variety of marine fishes travel well into the estuaries and

even into the freshwater during segments of their life cycle.
These include tarpon, mullet, and halfbeak. 7

NOTES FOR CHAPTER III

1. Porter E. Ward, Stuart H. Hoffard,, and Dan A. Davis, Geology
and Hydro ogy of Guam, Marianas Islands
Te-oTo-gl'cal Survey Profess'10nal Paper . 403-H
United States Government Printing Office, Washing-ton
D.C.,1965 pp. H346

2. Ibid., p. H6

3. U. S. Amy Corps of Engineers, Ugum River Interim Report and
Environmental Impact Statement, Stag -M!@Eo:rt
U. S. Army Enc Honolulu,
gineers District Report,
Hawaii, August, 1975 pp. 11-12

4. Ibid.

5. Ibid.

6. Ibid.

7. Ibid.

I
I
I
I
I
I
I
I
I
Chapter IV
I
I
I
I
I
I
I
I
I
I

-----------------
43.000 50,coo 65,000 60,000 6 a, 70.000

-yopoo
T0,000 -

x
I--
cc

93poo
aspoo -

64poo

.33.000 55,D10 -

MATGUE

-sopoo TATGUA
60,000-
APRA HARBOR 4 ASAN FONTE AGANA I(.
-IT4 4
.45.000 A UADA PAGO
PAULANA 45POO
GAUTA LI
APLACHA

YLIG

AYUGA
40POO ci 40,000 -
I

FINILC
TOGCHA
TALOFOFO 14
SAGU %.
.000 ci 35,000
MADOFAN 11
53

ASMAFIN

PAULILUC
UMATAG
30poo
3OdDOO
TOGUAN INARAJAN
19 1@4 A GP4 1, 10,000 0 10,000 20,000 30.000
r r-v-

SCALE IN FEET
NOTE:
23.000 1 MAPGRI ISSASEDON
ISLAND OF GUAM
GOVERNO ENT OF GUAM PLANE
M 0
CCORDINA7E SYSTEM RIGIN KEY T& DRAINAGE
iL AT AGANA MONUMENT
50,000 METERS NORTH AREA MAPS
50,000 METERS EAST

62
4OA00 4 5,MO 80@00 53.000 60.000

IV. THE RIVERS

Thirty-two major drainage basins have been studied in
this hydroelectric generation feasibility study. Thirty-one
drainage area maps are included in this report. The Agana
Swamp drainage area was omitted because the basin is
predominantly limestone, and the water produced there is
considered ground water. The Agana Springs are discussed, and
are the only water source in this drainage area worthy of
discussion relative to hydro development. I
The tabulation order begins at Orote Point going
northward, through the central area of Guam, southward along
the east coastline, around the southern tip and then northward
again to Orote Point. 2

Of the thirty-one drainage areas addressed, two have
been studied for major impoundment projects. Although all the
drainage areas will be discussed, attention will be focussed
on those areas considered to be developable as surface water
resources. This decision is based on the fact that the major
expense in. hydro development are the civil works - roads,
dams, piping, etc. With the exception of the Fena dam, no
existing impoundment area holds enough water too last through
any significant dry period while discharging water to hydro
applications. Consequently, any new development other than
for individual or small farm use should marry the hydro plant
to the fresh water production plant.

Ten drainage basins have been studied for surface water

supply and these will be the first priority group to be

addressed for hydro applications. Those that remain are

characterized as being either too small, too inaccessable, or

are normally dry during low rainfall months.

The ten major drainage basins are accompanied by

duration-discharge curves which show "normal" and dry

cu rves. The "normal" curve is based on the full record of the

stream, while the "dry" curve shows the daily flow for only

the year during which the stream flows were shown to be the
lowest.3

6.4

A. Pago River
Drainage area = 9.0 sq.mi
Located in the northeastern
section of the study area,
the Pago River drainage area
is comprised of the main Pago
River and its two principal
branches, the Lonfit and
Sigua Rivers. The confluence
of the two rivers is located
about 2.5 miles upstream of
the mouth of Pago Bay, and
join to form the PaTo River
at that intersection.

THE
STUDY
AREA
Gut
AA7' G U A

ASAM OMTE
APRA MARB-OR
S430 Geo-physical Notes for Pago
AGUADA River Basin
I-AGO. - mountainous to
PAULAwA Upper reaches
r CN& IqPMPP rolling terrain under-
"UT ALI
APLA -W,
lain by deeply weather
YLIG ed volcanic rock.
North slope - comprised of
ATUGA permeable limestone.
South slope - lies in volcanic
rock.Below the conflu-
IOGCMA ence of the Sigua and
7ALOFOFO Lonf i t, the stream
"A channel is in a valley
SAGU
9% flat which is underlain
by alluvium.
...... 14 Point of discharge: Pago BaY,
C. east coast of Guam-5

PAULILUC

INAMAJAN
JOCUAM

600

IX-

DRAINAGE
AREA BOUNDARY

3@0O

-----------

400

DURATION DISCHARGE CURVE

PAGO RIVEER NEAR ORDOT

Record 15 Years
1951 1967

Peziod oi Reco Di--ch--rec Equz! to or Exceeding - in M. G. D.
rd
5756 Days Z5 151 101 1 51 31 21 1. 51 1. 01 0. 61 0. 41 0. 2: 0. 11 0. 0
(Partial Years Included) 733 1 1?031 17101 ?2061 27391 34231 38241 408-51 4419 48501 52091 55461 .56301 -5756
No. of davs in Dr,,, Yr.* 1 37 571 731 931 1121 1-60 1731 180] 1921 2201 2471 2681 2901 365
Perccntace of time 110. 1 1 15. 61 20. 01 25. 51 30. 71 40.51 -47. 41 49. 31 5 2. 61 6 0. 3 167. 71 713. 4 1 79. 41 100
No. of davs in Av. Yr. 146.5 1 76. 3 110S. 1@1139. 91173. 7 1?17. ) ;242. 51259. 01 30. 3 1361. 7 1 357.
1 280. 21307. 613 01 365
PCrce,-.ta--:!e of t;mc 112.7 1 20. 9 1 29. 71 38. 31 47. 6 1 59. 51 66. 41 71. 01 7 6. 81 84. 3 1 90. 51 96. 3 1 97. 8 1 100
'Fiscal Year 65-66

Daysin Year

20 40 60 80 100 120 140 !60 180 200 220 240 260 280 300 320 340 36C

FLOW IN M. G. D.
20 Stream Max. Min.

P
go 3430 0
a.

FT
10-1 1 1 1 1 1 \1 I I NS I I I i i I I I I I I I I I I I

T7-T-
5 1 I-FF I -F-17-
k I NORMAL CURVE
r) 7 yC -L: R V F, I
Jz@
U

T-

F-171- -1-F F
T-T-F -i
r1i Ell :III
S

-17@

0 10 20 70 40 -0 bo 70 so go I C
USCS Sta. 80,50 Percc-ntage of Time -FI G U R IE
Elevation 251+ 67

DURATION DISCHARGE CURVE

LONFIT RIVER NEAR ORDOT

Record -8 Years
1951 - 1960

Discontinued Mar. 31, 1960

Period of Record Discharge Equal to or Exceeding - in M.G. D.
3110 Days 25 15 10 7 5 31 2 1. 5 1. 0 0.'6 '0. 4 0. 21 0. 1 1 0. 0
(Partial Years Included) 163 264 407 580 761 1 1104 1383 1554 1783 2089 21,09 2767 30191 3110
No. of davs in Drv Yr.* 15 26 42 57 78 105 1 8 152 202 236 258 294 3431 365
5 21. 3
Porcentage of timc 1 4. 1 7.1 11. 15. 6 4 28. 8 37.8 41.6 55. 64.7 70. 7 80. 5 94. 0 100
3 013Z4. 8
No. of days in A Yr. 19. 1 31.j 47. 8 68. 1 89. 31129. 5 162.. 3 182.4 209. 245. 2 365
Po_rcer,1,,'Qc o@ time 1* 2 1 8. 5F 18.6 ___ ____ _L_' 5 @73 67. 2 1 74. 21 89. 0,
13. 1 3 5. 5] 44, 5
*Fiscal Year 57-58 24. 51 ]50, 0

Daysin Year
20 40 60 so 100 120 140 160 180 200 220 240 260 280 300 320 340 69

FLOW INT M. G. D.
7.0 Stream Max. mi..

Not
Lonfit Deter- 0
mined

5. 0
-TI I I -I

3. 0
I N NORMAL C R E
1 -1 1 1 1 1 1 1
II I IJ
01. 0
DRY CURVE

N I

o.6

IF-I
_T_T
0', -F I
11* 2 T_ F_T_

o -T-T-
0 10 20 30 40 50 60 70 so 90 100
USGS Sta. 8620 Percentage of Time FIGURE
Elevation 301+ 68

Measurements. The flow duration curves and data are shown on

figures 4-3 and 4-4. These measurement records show that the

flows vary from 3,430 mgd to 0, for a period of record of
5,756 days.6

The average flow recorded at guaging station #8560 is
16.6 mgd. 90% of the time the flow is .45 mgd. This is
measured at guaging station #8650, which is 3.22 miles from

the estuary. There are two head waters located 5.65 miles
inland on the Lonfit River and 5.8 miles inland on the Sigua

River.

For 75 days, during the drought year of 1965 to 1966,
the Pago River flowed less than .1 mgd. For 49 days in this
period, 45 of which were continuous, there was no flow at
all.8

Power/head characteristics. Approximately 60% of the main
bodies of the Pago River flow is at an elevation of less than

100 feet. The remaining sections climb to an altitude of 800+

feet where the streams originate.

The elevation at guaging station #8560 is 25 feet.
This section of the River continues downstream at a gradual
fall. Consequently, any head that could be developed over,
say, 10 feet, would have to be created artificially by
dammi ng. The most promising head/flow combinations are found

from .5 miles upstream of the headwater locations on both the

Sigua and Lonfit down to the gauging station. On both rivers
the headwater location lies approximately halfway between the

200' and 100' contours.

The theoretical instantaneous power potential at the

headwater location, assuming a 25 foot head, a plant

efficiency of 80%, and flow by the headwater definition (5

CFS) is 11.34 M

The theoretical instantaneous power potential at the

guaging station, assuming the same plant efficiency, head of

10 ft and the average flow of the river (25.69 CFS) is 23.3 M

Assuming the same efficiency and head and assumin g flow

to be equal to the 90% case (.7 CFS), the instananeous

theoretical power potential is 630 watts. This disparity

shows the impact of the low flow and no flow periods. Because

of these periods, installations of around 10 kW would have to

be tied into the Guam Power Authority electrical system to

assure year-round power. This is, incidentally, the usual

case on Guam. Records indicate that all of the guaged rivers

have 90% cases which are quantitatively a fraction of the

average flow cases.

B . Ylig River

Drainage Area = 11.6 sq mi

The Ylig basin is located
just south of the Pago River
basin and is formed by
numerous tributaries includ-
ing the Tarzan River and the
Manengon River. The Ylig
River basin, approx. 5 miles
long and 3 miles wide at its
broadest point, is the main
source of water for the vil-
lage of Yona, which collects
the water from below the
gauging station.9

THE
STUDY
wATGUE AREA

rATCUA

ASAN rOMT1
APRA HARSO 41 4,J0
J4J

AGUADA
PAGO

PAULA "A
C A UT AL
@I
APLACK&

YLIG Geo-physical notes for the
AYUGA Yl i g Ri ver-Fa-si n

Upper reaches, main stream
and several tributaries -
70GCHI, flows on highly weathered
TALOPOF rock at steep gradient.
'U Lower reaches - deep valley
cut across narrow limestone
plateau.
Point of discharge - Y ig Bay,
ASUAFINES ov "00%, east coast of Guam.10
rAULILUC
UU&JAt

JWAIqAJAM
TOCUAM

VA,,

DRAINAGE
AREA BOUNDARY
L

'4001.-

300
200

300

-600

cz@
'300
so 0.)
cfl.

500
vo
100
ER

100
To

Soo

400 ,Po

DURATION DISCHARGE CURVE

YLIG RIVER NEAR YONA

Record 15 Years
195Z 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
5492 Days 25 15 10 7 5 3 2 1. 5 1.0 0.6 0.4 0. 2 0. 1 0. 0
(Partial Years Included) 810 1469 2183 2777 3194 1 3710 1 4038 4293 4643 4973 5205 5396 5451 5492
No. of davs in Drv Yr.* 37 58 89 118 1521 1741 192 ?051 Z27 254 271 299 3Z4 3651
Percentage of time 10. 1 15.9 24.4 32.3 41.61 47. 71 52.. 6 56. 2 6 .2 69.6 74.2 81.9 88.8 100
7\o. of days in Av. Y r. 53.8 97.67145.1 184.6 21 Z. 3 1 ?46. 6 JZ68. 4 285. 31308. 6 330.5 34 5. 91358. 6 362.3 36.5
Percentzge of time - 14.7 1 26. 71 39.71 50.61 58. 21 67. 51 7 3. 5 78. 21. 84. 5, 90. 5 1 94. 81 98. 2, 99. 2. 100
*Fiscal Year 65-66

Days in Year
20 40 60 80 1 0 lp 140 160 180 200 220 240 260 280* 300 320 340 36C

FLOW IN M. 0. D.
20 Stream Max. Min.

Ylig Z910 0.06

10 NORMAL CURVE

0 5

I IDRY CURVE

2 F-

0 10 20 30 40 so 60 70 so 90 10
USGS Sta. 8580 Percentage of Time FIGURE
Elevation 601+ 73

Measurements. The flow duration curves and data are shown on

figure 4-6. These measurements show that the flows vary from

a maximum of 2,910 mgd to a minimum of .06 mgd, for a period
of record of 5,492 days from 1952 to 1967. The average flow

of the Ylig River, measured at guaging station #8580, is 18.7
mgd. 90% of the time, the flow on the river is .71 mgd. 11

The Ylig has three head water locations: one on the

Ylig, 7.45 miles upstream, one on the Tarzan River 5.16 miles

upstream, and one on the Manengon River, 3.94 miles upstream

from Ylig Bay.

For 18.1% of the drought year of 1965-1966, the stream

flow was less than .2 mgd. The flow on the Ylig falls below
.4 mgd more often than 25% of the time during drought
12
years.

Power/head characteristics. Roughly half of the main bodies

of the Ylig River flow at of elevations less than 100 feet.

The remaining sections flow at elevations up to 300 to 400
feet for the bulk of the drainage area. The Ylig mainstream

extends well up into the highlands in one section to

elevations of 900+ feet where it originates.

The elevation at guaging station #8580 is 60 ft.
Located on the this lower reach, the section from the guaging
station to the estuary, has a low gradient. Consequently, any
head that could be developed over 20 feet would have to be
artifically created by a dam. This could prove impractical
because this section of the river runs across a highly
permeable limestone plateau and the leakage would be high.

In the upper reaches where the dense underground rock

would. permit damming, 'the steep gradients prohibit large

impoundments. The head/flow combinations are adequate to

support a smaller scale hydro, site (10 kW) for agricultural

puposes, provided the farm owner could locate a suitable
impoundment area. It should be noted 'that the bulk of the

Ylig is zoned conservation and only a small section of the

Central Ylig is zoned agricultural.

As in the Pago case, the Ylig has periods in excess of

two months that yield inadequate amounts of water for

substantial hydro, generation. At the guaging stations,

assuming a head of 15 feet, a plant. efficiency of 80%, and

using the.90% flow case (.71 CFS) the intantaneous theoretical

power potential would be .91 kW. At the same site, with the

same head and efficiency assumptions, the flow-duration curves

indicate that 15 kW of power could be available about 50% of

the time in the "normal year". With the same assumptions, the

average flow would yield a bout 39.37 kW, which corresponds to

the 22% case.

At the headwater locations, particularly the Ylig

mainstream headwater, much higher heads (50-70 ft.) are

available, but access and impoundment potential are more

limited. Although 20 - 35 kW could theoretically be

developed, using hardware such as a "Pelton" plant, that could

utilize 50 to 75 feet of head at low average flows (5 CFS) to

develop that amount of power.

C Talafofo River

Drainage area = 20.8 sq mi

The Talofofo River basin
lies south of the Ylig River
basin and is the largest
river basin on Guam. The
Talofofo River is that
stretch below the confluence
of the Maagas and Mahlac
Rivers, two of the many
tributaries that feet the
Talofofo including the
Talisay, Bonya, -Maemong,
Talifac, Maulap, Almagosa,
Imong, Tinechong, Sagge, and
Sarasa Rivers. A dam
contructed across the val 1 ey
above the confluence of the
Maaga and Tolaeyuus (Lost
River) forms the Fena Valley THE
Reservoir which su plies the STUDY
Navy water system.lT
TGUE AREA

'ATGUA

ASAX FOXTE

APRA HARBOR
4
AGUADA Geo-physical notes for the
PA60 Talofofo River basin.

PAULA"A
.. UT,I
AP LACHA General - The main Talofofo
River valley floor and the
YLIG larger tributaries a re
underlaid by alluvium.
AYUGA
River basin - underlain
A largely by volcanic rocks
and noncalcareous sediments
FIRM TorCHA which are deeply weathered.
TALOfOfO Northern side - Upper
S & Clu tributaries, the Talisay,
Bonya, Maemong, and
Tolaeyuus Rivers, flow
across limestone terrain.
ASUAFINES -0 SO Sections of the Maemong and
Tolaeyuus flow underground
PAULILUC in a limestone cavern.
West side - Limestone caps
114AMAJAN occur on hills on west side
TOGUAN of basin f ormi ng numerous
A0, springs. The Almagosa
14 Spring is one which is of
major importance.
Point of drainage - Talofofo
Bay, east coast of Guam.14

DURATION DISCHARGE CURVE

FENA DAM SPILLWAY NEAR AGAT

Record 15 Years
1951 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
5651 Days Z5 15 10 7 5 3 2 1. 5 ). 0 0.6 0.41 0.2 0.
(Partial Years Included) 637 1052 1420 1718 1976 2084 2175 2269 2273 2352 2::3:5@8] ?429 2434 5651
No. of davs in Dry Yr.* 11 16 30 38 50 54 56 61 61 69 691 70 70 366
Percentage of time 3. 0 4.4 8. 2 10. 4 13. 7 14.8 15. 3 16. 7 16. 7 18. 9 18-91 19. 1 19. 1 100
'No. ef davs in Av. Y r. 41 68 -92 111 128 135 141 1 1471 147 152 152 157 15L 365-
Percenta-ge of time 3 4 35 4 4 61 41.
11.1 18. 6 25. 2.1 0. 1 37. 0 38. 6 1 0. 31 0. 3 41. A I.4A 0 43. 0 100
*Fiscal Year 59-60

Days in Year
20 40 60 80 1 '0 120 140 160 180 200 220 240 260 280 300 320 340 36(

FLOW INT M. G. D.
-_ T_
7. 0-1 1 1. Stream T-Ma.. Mi..
I X I I Not
Fena Spillway Deter- 0
mined
5. 0

I I I I I -T I
I I 1--F-

3. 0

-a--,9N0RMAL CURVE

1.0

FF
U
IDP Y CURVE

0. 6

0.4

0. 2
M-F
0
0 10 20 30 40 50 bo 70 8u 90 loc
USGS Sta. 8490 Percentage of Time FIGURE
Elevation 1111 81

L-4=

0 AMAGE
A
AREA SOUNOARY

-7k
RlION
@CMIVJA RESE
-F ......
r\

6-
r
f kk@
7>\1
FENA
Y
0 VALLEY
R
E OR

R
A

POIN
4 1

M
Li
E

-All

.1 Y R
ILI AT!P

zz 7
1@7 TALOFOFO DRAINA
J,

DURATION DISCHARGE CURVE

TALOFOFC, (MAAGAS)

Record - 10 Years
1951 - 1962
Discontinued June 30, 196Z

Poriod of Record Discharge Fqtial to or Exceeding - in M. G. D.
3SSI Days 75 501 25 151 10 71 5 31 1. 01 0. 61 0.41 0. 2
-(Partial Yoars Included) 326 5541 1023 14871 180Z 2014 22651 Z703 3048 3Z901 36841 38321 3879 3881
": 0, 0, C, avs in Drv Yr.* 17 31 84 153 234 2551 3061 3481 366 366
Perccnta-_@c of time 4.6 S. 5 22. 9 30. 31 34. 1 41.8 4 5. 9 1 5?. 5 63.91 69.71 83.61 95. 1 1 100 100
No. of days in Av. Y r. 30.7 52. 1 96. 2 139. 81169. 51 189. 4 1286. 6 1309. 41346. 5 1360. 4 1364. 8 365
Perconta-le of tin-ic 8.4 14.3 26. 3 1 38. 1 46. 41 5 1. 91 58. 31 69. 61-78. 51 84. 81 94. 91 98. 7 1 91). 91 100
*Fiscal Year 59-60

Days in Year

20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 36C
25
+

F LOW L-11 M. G. D.
20 St rcam Ma.7FMin.

Talofofo 2310 .34

1%
. . ....... ... .... . ....

NORMAL CURVE

Cz DRY CUR \'E

lit
168 192

213. 0 254. 2

:::F:f I I J 1=1 I =7 I-T-FT-1 -11-F-F-F
0
6 10 ?0 30 40 50 60 70 so 90
USGS Sta. 8500 Percentage of Time FIGUR E
Elevation 201+ 78

DURATION DISCHARGE CURVE

TOL.AEYUUS RIVER NE AR AGAT

Record -8 Years
1951 - 1960
Discontinued July 18, 1960

Period of Record Discharge Equal to or Exceeding - in M. G. D.
3217 Days 25 15 1-0 - 71 51 31 2 0.61 0. 4j 0. 2 1 0. 1 0.0
(Partial Years Included) 374 664 9511 )2191 14491 1-7931 7025 21851 ?4821 28241 3058 3199 1 3217 3? 17
No. of davs in Dry Yr.* 39 62 871 1241 1541 1791 196 214 255 304 334 357 366 366
Percentace of time 10.7 16.9 23* 81 33. 91 4?.11 49.01 53. T- 58. 5 69. 7 83. 1 91. 21 97. 5 100 100
No. of davs in Av. Yr. 42.4 75. 3 1107. 9 1 138. 31164. ; 1203. 4 1?29 8 247. 9 281. 613?0. 4 347.OF 363 365 .365
Percenta-pe of tirne 11. 6 20. 6 1 29. 61 37. 91 4 5. 01 5 5. 7 1 6 2. 9 1 6 7. 9 95. 1199. 4 100 100
*Fiscal Year 59-60

Daysin Year
20 40 60 80 100 120 140 16o 180 200 220 240 260 280 300 320 340 69

FLOW IN M. G. D.
9. Sirearn Max. Min.
Un-
Tolaeyuus known 0.13

6. c

@INIORMAL CURVE

3. C

DRY CURVE'

L) 7.

1.5

1. C

0. E

__F_F 1 1 1 1 1 1 -1"S, 7S
IN

I I I I I I I I I I I I
o L-I I T_ I I I I I I I I I I I@-l I I I 1 3
o 10 20 30 40 50 60 70 so 90 100

USGS Sta. 8450 Percentage of Time FIGURE
Elevation 901+ 79

DURATION DISCHARGE CURVE

IMONG RIVER NEAR AGAT

Record 6 Years
1960 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
2306 Days 25 15 101 71 51 31 2 1. 51 1. 0 0. 61 0.41 0. 21 0. 1 1 0. 0
(Partial Years Included) 99 187 2831 446 70S IZ511 1612 1818 2082 22531 22811 ?3061 2306 23106
238 365
-X0. of d:ws in Drv Yr.* 6 12 21 35 581 1171 171 192 312 3401 3651 365
11crcentace of time 1.6 3. 3 5. 7 9. 6 15. 9] 32. 0] 46.8 52. 6 65. 2 85.51 93.1 1001 100 100
Nr- o"' davs in Av. Yr. 15 7T29 5. 9 1447. 8 705. 71 1 1Z. 11 197. 91255. 1 28 7. 6 13 2 9. 4 13 5 6. 5 13 60. 9 365. 0 1365. 0 136.5. 0
Pcrcenta@gc of time 1 4. 3 1 8. 1 1 12. 3 19. 31 30. 71 54, 2T69, 91 78. 8 1 90. 21 97. 7 1 98. 9 1001 1001 100
*Fiscal Year 65-66

Daysin Year
20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 6q

FLOW IN M. G. D.
9. 0 Stream FIV, Min.

Imong 2180 0. 24

6*0

3. 0

NORMAL CUR N'E

DR CURVE.
Q

2
0
.

1. 5

FF FTF T-FL
0. 5
NH

-H
@IsEj-]
IN
0-TI I I I I -H I I j.. 1 1 1 H-1- I I--1-j 1' i,ll@Ni
0 10 zo 30 40 50 bo 70 80 90 100
USGS Sta. 8470 Percentage of Time FIGURE
Elevation 1201+ 80

DURATION DISCHARGE CURVE

FENA DAM SPILLWAY NEAR AGAT

Record 15 Years
1951 1967

Period of Record - Discharge Equal to or Exceeding - in M.G. D.
5651 Days Z5 151 10 7 1 5 1 3 2 1.5 1. 0 0. 6 0.41- 0.2 0. 1 1 0.0
(Partial Years Included) 637 1052 1420 1718 1976 2084 2175 2269 2273 2352 2358 2429 2434 5651
7 11 30 38 50 56 61 61 69 69 70 70 366
No. of davs in Drv Yr.M' 16 54
Percentage of time .0 4.4 8.2 10.4 13. 7 14.8 15.3 16.7 16. 7 18.9 18.9 19.1 1 19. 1 100
7 ef davs in Av. Yr. 41 68 92 Ill
Xo. 128 135 1 141 1471 147 152 1521 157 LuIT_365 -
Perccnta7gr of time 11.2 1 18. 6 1 25. 2 30.4 35. 1 1 37.0 1 38.6 1 40.31 40.3 ..41. 61 41. 61 43. 0 1 43.-0 100
*Fiscal Year 59-60

Days in Year
20 40 60 80 1'0 120 140 160 180 200 220 240 260 280 300 320 40 6q

FLOW INI M. G. D.
7.0 Stream Max. mi..

N
I IF,n e 0'
a Spillway@D t"'- 0
rniried
5.0

I F

3*0

w-wNORM L CUR VE
01.0

DRY CURVE
-77-7 1

0. 6

0. 4

0. 2
H-41

@#D

I I I U11
0 10 zo 30 40 5u bo 70 so 90 loc
0 .
USGS Sta. 8490 Percentage of Time FIGURE
Elevation 1111 81

DURATION DISCHARGE CURVE

ALMAGOSA SPRINGS NEAR AGAT

Record- 15 Years
1951- 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
575.1 Days 25 15 10 7 5 3 2 1. 5 1.0 0.61 0.4 0. Z 0. 1 0. 0
(Partial Years Included) 56 149 311 507 760 1186 1549 1787 211.1 25341 2838 3251 3801 5754
of davs in Drv Yr.* z 7 10 1z 16 27 44 56 65 74 85 130 181 365
Pcrccnta.@c of time 0. 5 1.9 2. 7 3. 3 4.4 7.4 1Z. 0 15.3 17.8 20. 3 23. 3 35. 6 49. 6 100
3. 5 9.4 19.7 113. 3 134. 11160. 7118 0. 012 0 6. L24 1.
No. of days in Av. Y r. 32. 2 48. 2 75. 2 98. 3 2 1 365
e 0.9 8. 81 13. 2 1 -F .0 100
Perccntxgc of tim ?-- 6 5- 4 20. 61 26.9 31. 01 36.71_44.01 4973 56. fl 66. 0
:,Fiscal Year 65-66

Days in Year
20 0 60 8 100 120 140 1.60 180 200 220 Z40 260 280 300 320 340 36(

FLOW D@: M. G. D.
7.0 Stream Max. Min.-

Alma.uosa 497 0

5. 0

3. 0

1.0

Lj I
00.8 NORIMAL C17RN'E
u

o. 6
DRY CURVE

0. 4

0. 2 FF
-LL

0
0 10 20 30 40 50 60 70 80 90 0
USGS Sta. 8480 Pcrccnt.Ngc of Time C, T-T R F."
T-, I (,'V,.L t i on 640' 1 82

Measurements. There are five major guaging stations in the

Talofofo River basin. The flow duration curves and data from
these stations are shown in figures 4-8, 4-9, 4-10, 4-11, and

4-12.
The Talofofo River is guaged at #8500 and recorded from
1951 through 1962. This gauging station is located on the
Talofofo just below the intersection of the Maagas and Mahlac
Rivers. The average flow at this station is 32.9 mgd and is
the largest annual flow recorded on Guam.. In the lower
reaches, the bulk of this flow results from precipitation
runoff, not spring activity, so although the Talofofo River
has the highest recorded average flow, it is only third in
terms of the 90% case. Ninety percent of the time, the flow
15
is 1.16 mgd, about half that of the Ugum River.

The Talofofo River has four headwater locations. One
is on the Tinechong River, 3.41 miles upstream; one on the
Mahlac River, 4.22 miles upstream; one on the Bonya River,
6.25 miles upstream, and one on the Maemong River, 8.84 miles
upstream from the ocean point of discharge, Talofofo Bay.

Note that both the Mae mong and Bonya Rivers flow
through underground limestone caverns and disappear as surface
flow streams near their confluences. The Maemong disapppears
for less than 1,000 feet prior to its confluence with the
lower Bonya River (Tolaeyuus) and the Tolaeyuus River
disappears as surface flow for less than 2,000 feet above its
confluence with the Maagas River. The distance to the
headwater locations was calculated as though the rivers were

bodies of continuous surface flow.

Guaging station #8450 recorded the flow of th e

Tolaeyuus River (.05) near Agat (Drainage area = 6.54 sq. mi.)

for the period 1951 to 1960. The maximum flow of this river

during this period is unknown and -the minimum flow is .13

mgd. The average flow at this station is 13.6 mgd. 90% of

the time the flow at this station is .52 mgd. The flow

duration curves for this station are shown in figure 4-9.

The Imong River near Agat is guaged at station #8470

for a period from 1960 to 1967, during which period a maximum

flow of 2180 mgd and a minimum of .214 mgd was recorded. The

average flow of the Imong River, which has a drainage area of

1.95 sq. mi., is 6.59 mgd. 90% of the time the flow at this

station equals 1.10 mgd.

There are two other major guaging stations in this

basin, one for the Fena Dam spillway, #8490, and one for the

Almagosa Springs, #8480. The flow duration curves for the

Fena station, shown in figure 4-10, has a unique, nearly

vertical c urve. This curve indicates that the discharge at

the spillway is 0 for 56% of the time, but a rather high 10

mgd about 25% of the time.

The Almagosa Springs guaging station lies at an

elevation of 640 ft at what is the very origin of the Almagosa

River. The maximum flow recorded at this station is 497 mgd,

the minimum flow is 0. The elevation, and consequently the

potential head of this source, makes it noteworthy. However,

the flow is usually rather small at about 3 mgd for 20% of the

time, tapering to .1 mgd 6% of the time.

811

The fact that the military already pumps from the

Almagosa Springs, coupled with the required long reaches of

expensive penstock, diminishes the impact of this hydro

resource.

Power/head characteristics. The majority of the drainage area

of the Talofofo River basin lies at elevations greater than

100 feet. The northern tributaries of the Talofofo which

include the Talisay, Maemong, Bonya and Talaeyuus, and Mahlac

Rivers, all lie on the interior basin, a section of rolling

lowlands and karst. Heads of 20 to 25 feet may be created

with a minimum of civil works. The elevation of guaging

station #8450 is shown to be 90 feet while contour maps show

the upper Maagas which is less than 3,500 feet away at an

elevation between 20 to 40 feet. This means that there is

between 50 to 70 feet of head potential in that section

alone. Based on this, it is safe to assume sections with the.

heads of 30 to 40 feet are available with limited civil works

construction such as large impoundment areas or extended

penstocks.

This section of the river, however, is the section that

flows through underground caverns of limestone, where

impoundment leakage could be a problem. Assuming a good
impoundment area could be targetted and constructed, power in
the order of 57 kW to 75 kW could theoretically be generated
beased on the average flow of station #8450 (13.6 mgd) which

corresponds to the 23% case. This is based on 30 to 40 foot

head, and plant efficiency of 80%. With the same assumptions

and using the 50% flow case the instantaneous theoretical

potential, is between 16.,8 kW and 22.5 M There are many
sections that could support a small farm application of 3 to

10 kW of hydrogenerated power, providing an acceptable

potential impoundment area and construction access road are

already available.

The Fena dam, which presently impounds about 2.3

billion gallons, could bE, augmented with a 135 kW power plant

that could produce 327,069 kWh per year at a plant factor of

32%. This was calculated assuming 75 feet of head, plant

efficiency of 80%, and a flow range of 30 to 110% of the

des ign case for the turbine (3 mgd to 15 mgd) based on the

amount of water that is presently diverted over the spillway

at the dam. This power also could be used right at the dam

which has four 3,500 gpm, 300 horsepower pumps installed to

deliver the water three miles to the Fena Water Treatment

Plant.

The lower reaches of the Talofofo flows across the

alluvial valley floor. This final section of the river has a

low gradient which would require the'artificial head of a

dam. The permeability of the ground would vary, depending on

the type of soil deposits found in a particular area. This

makes it particularly important to have any potential damsite

thoroughly investigated by a professional who could target an

area and design a long-lasting, tight dam that would endure.

D. Ugum River

Drainage area = 7.3 sq. mi

Lying immediately south
of the Talofofo River basin,
the Ugum River drainage area
is comprised of the main Ugum
River and its major
tributary, the Bubualao
River. The Ugum River joins
the Talafofo about a half
mile from its discharge
point, Talofofo . Bay *
Dividing the upper and lower
reaches bf the river is
Talofofo Falls a scenic
tourist attraction.16 THE
STUDY
WiIGUE AREA

TATCUA

ASAM FONTE

APRA HARBOR
34

AGUADA
PAGO. Geo-physical notes for the
P A UL ANA Uquam River basin
r A UTALI.
LA MA
General - mostly underlain
YLIG with deeply weathered,
AYUGA consolidated, non-cal-
careous sediments derived
from volcanic rock.
ToGCNA Upper reaches - soils composed
FINILE 7.1.0roro of Atate-Agat clays.
Lower reaches - valley flats
JAGU underlain by alluvium and
soils composed of
moderatedly well-drained
'0 Pago clays.
A S U A, F I N E S Talofofo Falls - dense
basaltic rock outcropping
rAULILUC dividing the upper and
A, C lower river reaches.
INAMAJAN Point of discharge - Talofofo
TOGUAM River.17

NtoporC
DRAINAGE POINT OF DEVELOPMENT
AREA BOUNDARY (COORO ih METERS)
N 3 3,299
E 48,445

"- 11-0

S,-

00
00

...........i

J-?
V

oo::

DURATION DISCHARGE CURVE

UGUM RIVERNEAR TALOFOFO

2,0 40 60 sp Igo ip 1@0 1�0 ISO 200 220 240 260 280 300 320 340 36(
30

22
I
-lid 1-1 1 1
7- 1 1 1 1 1 1 11 1 1 1 1 1 1T- 1-1 TI I I I
II I I I I LJ= I I I I I
I II I I I I I JI I - III I I
1 NORMAL CURVE - UGUM RIVER
ON
AT GAGING STAT1
14 -T-

''0

t
6 1 FT
i I I
u
CURVE AT UGUM RIVER ABOVE
F 5 TALOFOFO FALLS - FROM
U. S. G. S. MISCELLANEOUS -F--1 T
MEASUREMENTS

L FT 1
-T- I i I I I I I I I I I II I II I I I II I I I 11 1 i I 'r- I I I I
3 1 1 -4+1-1 1 11 1 1 1 -1 1 -171 1 1 1 111 "1

I -T- I -T -1

---------------

I FFT
=F4

L+ @11

I LI
=R1

r
J-
0 10 20 30 40 50 60 70 so 90
R7.
USGS Sta. 8550 Percentage of Time
Misc. Measurements 89

DURATION DISCHARGE CURVE

UGUM RIVER NEAR TALOFOFO

Record 15 Years
1952 1967

Period of Record Discharge Eaual to or Exceedin@ - in M. G. D.
5491 Days 75 50 1 25 1 15 1 10 7 5 3 1 Z 1 1. 5 1 1. 0 0.6 0.4 F0. ?
(Partial Years Included) 177 1 319 1962 11983 1?895 13563 4086 1 5072 1 5461 15491 15491 5491 5491 15491
rv Yr.* 7 12 1 32 1 69 1 139 1 174 1 365
No. of days in D 199 T 269 335 1 365 1 365 365 365
Percentage of time 1. 9 3. 3 8. 8 118. 9, 138. 1 147. 7 154. 5 173. 7 191. 8 100 100 100 100 F1 -00
No. of davs in All. Y =r I z 21 64 1 - 132 119? 1 237 1 ?72 365 365 365 365 1 365
Percentage of time 3. ? 5. 8 17.-5 136. 1 15 ?. 7 164.9 174.4 192. 4 199. 5 100 100 100 100 F 10-0

*Fiscal Year 65-66

Days in Year
20 40 60 80 100 1@0 140 160 180 200 220 240 260 280 300 320 340 69

FLOW r'Z M. G. D.
40 -TT Stream M. -.x - TM, i
-T-
-T
ug"", 41-10 1, 61

'0 FF f,44-- I I I I 1 1 1 1 1 1 1
N R-VE
'ORMAL CU
?

r- r j I
6 10 1 TJ

DRY CURVE
iNL 1

1 1 1 N1 I I 1 7
6

?
-17 1 1
- 4111,11,

0
0 10 20 30 40 50 60 70 so 90 loc
USGS Sta. 8550 Percentage of Time
El evation 3. 231 90 F IGU R E

Measurements. The flow duration curves and data for the Ugum
are shown in.figures 4-14 and 4-15. These measurement records
show that the flows vary from a maximum of 4$950 mgd to a
minimum of 1.68 mgd, for a period of record of 5,491 days.
The Ugum is guaged near its confluence with the
Talofofo River. The average flow at this station, #8550, is
19.0 mgd. 90% of the time the flow equaled or exceeded 3.30
mgd, the highest 90% case on Guam. The Ugum has two headwater
locations, one on the main Ugum River at a point 6.05 miles
upstream from its confluence with the Talofofo, and one on the
Bubualao River, 2.78 miles upstream from its confluence with

the Ugum River.

Other measurements were taken during the low flow years
from 1961 to 1966 at a guaging station located about 3,000
feet upstream from Talofofo Falls. The measurements from this
station revealed that at a guaged flow of less than 3.76 mgd,
the flow upstream was greater than the flow at the downstream
guaging station. This happens due to the discharge of the
numerous small seeps and springs in the upper reaches of the
Ugum River basin which contribute significantly to the stream
flow during low flow periods. The tight clay formations
underlaying the upper reaches prevent seepage. Consequently,
the river flow increases until it hits those downstream
sections underlain by the porous or less saturated soils which
soak up the streamflow before it reaches the *downstream
guaging station. 18
The effect is dramatic. On April 4, 1968, the Ugum

flow was measured immediately above the Talofofo Falls showing

a flow of 9 mgd while the guaging station downstream measured

only 5.2 mgd. It is thought that the dense basaltic rock

barrier of the Falls fon:es the seepage flows to the surface

in order for it to pass over the Falls. Once over and past

the falls, the water slowly seeps back into the more porous

soil of the alluvium, at a rate dependent on the ground water
level within the soil and the gradient of the stream. 19

In the Geological Survey Professional Paper 403-H,

entitled Hydrology of Guam by Ward, Hoffard and Davis,
1965, 20 this Ugum Ri ver phenomenon is discussed with

reference to the Inarajan, Pago and Ylig River basins.
Sections of this report ire reproduced below for reference:

... the Ugum River has the lowest rate of
recession of base flow among the major streams
on Guam. The stream basin is mainly in hilly
upland underlain by conglomerate, breccia, and
sandstone and shale beds. Diffuse ground-water
discharge from the fragmental rock maintains
the low flow of the stream. The lowest daily
discharge during 'the period of record was 3.4
cfs (cubic feet per second).

The low flows in the Inarajan and Umatac
Rivers are smaller and somewhat less sustained
than the low flow of the Ugum. The geol ogy of
the basin of the Inarajan is similar to that of
the Ugum basin and the low flow in the stream
is maintained by diffuse ground-water discharge
and by small springs at the heads of gulleys in
the mountainous part of the basin. Small
springs in lavas and limestone lenses within
the lavas supply the low flow of the Umatac
River.

The rock in the basins of -the Ylig and Pago
Rivers above the guaging points is mostly
fine-grained tuff grading to fine sandstone.
This terra apparently absorbs less rainfall and

has less ground-water storage than the rock in
the basin of the Ugum River, which has a
comparable size. Consequently, the low flow in
the Ylig and Pago Rivers may drop to or near
zero during droughts.

The variability of low flow among the
streams of Guam is shown also in the low-flow
frequency curves for the Ugum River and the
Pago River. In the Ugum River, the lowest
1-day mean discharge at a recurrence interval
of 10 years is 3.4 cfs. This same flow in the
Pago River is the lowest 60-day mean discharge
likely to occur every 1.1 years. The lowest
60-day mean discharge having a 1.1 year
recurrence interval in the Ugum River is about
12 cfs. This spread in low-flow magnitudes and
frequencies is large in view of the fact that
the average discharge in the Ugum River is only
about 20 percent greater than that of the Pago
River.

Power/head combinations. The bulk of the Ugum River flows at

an elevation higher than 100 feet. Over 80% of the basin is

above the 200 foot contour. In terms of potential head, this

drainage area is among the best, with numerous sections having

25 to 50 head available with low civil works requirements.

The premium sections are those in the vicinity of the

confluence of the Ugum and Bubulao River, but a small (2-10

W hydro plant location could theoretically be targetted

anywhere on the main Ugum River from the headwater location on

down to the valley flats provided a suitable impoundment area

and access road were available. The head/flow combinations

required to support a 10 kW plant are found beginning at the

-headwater locations of the Ugum and Bubulao extending

downstream to just below Talofofo Falls.

The site of the proposed Ugum River dam is by the far

the best site for a hydro installation on Guam. The

plan for the proposed dam is to impound 12 mgd of water, 9 mgd

of which would be retained for irrigation and agricultural

uses while maintaining the streamflow with a 3 mgd discharge.

With just the addition of a power pliant at the proposed dam,

over 400,000 kWh of power could be generated in a year using

the daily 3 mgd discharge. This translates into 33,333 kWh
per month, which would power a sizable single 'facility or

about 50 homes. This calculation is based on a head of 110

feet and a plant efficiency of 85%.

If the daily discharge were doubled then 800,000 kWh

could be generated in a year or 100 homes could be.provided

with electrical power.

Furthermore, if the power plant were placed at the

proposed dam, then the discharge could be reused downstream as
the head permits. Theoretically, as the river flows from the
dam power plant (elevation 190 ft.) to the Talofofo River

(elevation 20 ft.), seventeen 100 foot dams could be built to

use the 3 mgd discharge, producing over 4 kW each, for a total

of over 71 kW of additional power.

As mentioned earlier, professional soil expertise would
be particulary necessary in targetting impoundment areas in

the Ugum lower alluvial reaches.

E. Pauliluc River

Drainage area = 3.5 sq mi
Located in the
southeastern section of the
study area and sorrounded by
the Ugum, Asalonso, and
Inarajan River basins, the
Pauliluc drainage area is
comprised of the main
Pauliluc River and its two
major tri butari es, the
Aslinget and Tinaga Rivers
The confluence of these tw;
rivers is located about two
thousand feet upstream of the
Pauliluc Bay where they join
to form the Pauliluc
River.21 THE
STUDY
WATGUE AREA

TATGUA

A SAN FONTE

APRA HARBOR
4 Geo-physical notes for the
AGUADA PASO Pauliluc River basin.

PAVLANA
GAuT AL' General - rolling terrain,
L
APLAI.A mostly underlain by
deposits of breccia,
YL14 conglomerates, sandstone
AYUGA and shale derived from
volcanic rock.
Upper reaches - region of
TOGCMA gently rolling areas
Stream and tributaries
'FALVFOFO have low gradient.
S A Lower reaches - approximately
C.
one mile upstream from its
A..IA mouth, the stream gradient
steepens through narrow
ASWAFINES walled valley producing
several small waterfalls.
rAULILUC Sediment - the water has a
high sediment content.
INAA&JAX The suspended material in
70GUAN the water, which
U A CPA r4" discharges from the marshy
'4 area in the upper reaches
during low flow periods,
gives it a red color.
Point of discharge - Pauliluc
Bay, southeastern coast of
Guam.22

DRAINAGE
AREA BOUND

Ic,

"00

.100
0%

N%.

PAUULUC BAY

DURATION DISCHARGE CURVE

PAULILUC RIVER NEAR INARAJAN

Record- 14 Years
1952 - 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
5383 Days 25 101 7 51 3 ?1 1. 5 1. 01 - 0. 61 0. 41 0. 2 0. 1 0. 0,
(Pa'rtial Years Included) 132 345 497 741 1309 1 1973 1 2439 3160 1 37801 4262 5 19? 5383 53831
No. of davs in Drv Yr.
Perccritage of time
Nla. of davs in Av. Y r. 8.9 15. 8 23.4 33. 7 50. 2 88.7 1133. 8 165. 4,214. 3 256. 3 289. 01352. 0 1 3651 365
Perccrita-pe of time ?. 4 4. 3 6. 4 9. 21 13. 8 1_24. 3 1 36.6 70. 21 79. 21 96. 4 1 1001 10

Days in Year
20 40 60 80 100 120 140 160 180 200 2ZO 240 260 280 300 320 340 36C

FLOW 17,@ M. G. D.
7. 0- Stream Max. Min.

Pauliluc 1930 0. 10

5.0

3.0
'NORMAL CURVE
I FFTT I I

01.0

0. 8 -
U

F
47' 1
0. 6

IIL-
0.4

0.2 'r-77 I
-H-L4
UU-1 I I
0
0 10 20 30 40 50 60 70 so 90 10C
USGS Sta. 8400 Percentage of Time FIGURE
Elevation 201+ 97

Measurements. The flow duration curves and data are shown in

figure 4-17 for a period of record from 1952 to 1967. This
guaging station #8400 is located above the confluence of the
Tianaga and Aslinget Rivers and measures only the flow of the
Tinaga River which has a drainage area of 1.89 sq. mi. (54% of
the total Pauliluc River drainage area). Since the Aslinget
River is not guaged, the flow can only be estimated based on
the proportional size of its drainage area relative to the
Tinaga drainage area. Based on this method of estimation,
Aslinget River flow could be assumed to be roughly 85% of the
flow for the Tinaga River.
The average flow of the Tinaga River is 3.68 mgd, and
the 90% flow case is .26 mgd. The highest streamflow recorded
for the Tinaga is 1930 mgd, while the minimum flow was
recorded at .1 mgd. The Tinaga headwater location is .97
miles upstream from the Pauliluc discharge point, Pauliluc Bay.
The average flow of the Aslinget is estimated to be
3.13 mgd. The headwater location for the Aslinget is .83 mles
upstream from its confluence with the Tinaga.

Power/head characteristics. Approximately 80% of the Pauliluc
drainage area is at an elevation above 200 feet. The majority
of this area is rolling hills at elevations between 200 and

300 feet.

There is a section on both the Tinaga and Aslinget
Rivers that falls from the 200 foot contour to the 100 foot

contour in less than 2,000 feet. Provided that an impoundment

area could be located nea,r this section, a 50 foot head could

reasonably be projected. The most attractive head/flow

combinations are located from just above the 200 foot contour

down to immediately below the guaging station.

Unfortunately, there are specific limiting factors to

hydro development on the Pauliluc basin. First, the flows are

small when compared to its neighbor river basins, the Ugum and

the Inarajan Rivers. Second, the upper reaches of the

Pauliluc are inhabited and the rolling hills are used for

pasture land. Consequently, control of bacterial pollution

and chemical contamination would be extremely difficult,

eliminating any attactive water sales to the Public Utilities

Agency of Guam. Finally, the high sediment content of the

river could be a potential maintenance problem to the turbine
blades in the form of pitting. 23

Assuming the pitting problem could be addressed, a
plant on the Tinaga designed to use 3 mgd (30-110% of the

design case) at 50' head, could generate 87,000 kWh a year

from a 20 kW plant.

F. Inarajan River

Drainage area = 5.0 sq mi

The Inarajan River basin is
located in the southern
section of the study area,
just South and' adjacent to
the Ugum and Pauliluc
drainage areas. the river
basin is comprised of two
main tributaries, the
Pasamano and Laolao Rivers
and the main Inarajan River
which is formed at the
confluence of the tributaries
at a point .8 miles upstream
from the ocean discharge THE
point, Inarajan Bay.24 STUDY
.AYGUE AREA

TATGUA

ASAM ONTE
4,
APRA HARBO 0
34
#fUADA PA 6 0 Geophysical notes for the
Inarajan River-@a'sin
PAUL AWA
C A-TALI
APLACKA General - approximate basin
YLIO dimensions, 3.5 miles long,
2 miles wide.
AYUGA Two main branches - flow in
A small gorges over much of
their stream length.
TOGCMA Upper reaches - numerous small
JALOFOfO seeps and spri ngs at the
heads of the gorges i n
ZAGU mountainous portions of the
basin which contribute to
OOF AN the base flow of the
ASUAFINES -60 drainage.
East fork of the North Branch
PAULILUC supplies the village of
Inarajan with average of
50,000 gpd for domestic
UAN INARAJAN water supply.
Lower reaches - coastal
@4 lowlands and alluvial
valley floors.
Point of drainage - Inarajan
Bay, southern coast of
Guam.25

100

too
POIN
ORAINAGE
.7N
AREA BOUNDAF"

d p

.w.
............ ......
wd'
0, ...
p
.14:
...........
OOW
............
.........
.. .... .. . .. .
300 ...4
0.
...... .. .....
a
....... ..
. . ........ ..
. . .........
. ......... ..
. . .......
. ......... . .
x

.i6@
............
-Z7

INAftA.1
M.

'o.

elN. /
4 . . . . . . . . . .

DURATION DISCHARGE CURVE

INARAJAN RIVER NEAR INARAJAN

Record 14 Years
195Z 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
5404 Days 50 251 15 10 71 51 3 2 1. 5 1. 01 0.6 0. 41 0. z 1 0. 1
(Partial Years Included) 197 398 676 1136 1791 2462 3414 4042 4517 52451 5404 5404 5404 540-1
No. of days in Dry Yr.* 7 11 23 38 80 124 169 197 222 289 365 365 3(5 365
Percentage of time 1.9 3. 0 6.3 10.4 21. 9 34.0 46. 3 54. 0 60.8 79.?l 100, 300 1 C 0 100
No. of davs in Av. Y r. 13 * 31 26.9 45.7 76.7 1121. 01166. 3 305.1 1 3 -5 4=3 365. 01 365. 01365. 0 1 365. 0
Percenta-cc of time 3.6 1 7.4 1 12. 5 21. 0 1 33, 1T4 5. 6] 63.1 1 74. 81 8 3., 6 1 97. 11 1001 1001 1001 100
*Fiscal Year 65-66

Days in Year
20 40 60 8 lbo 120 140 160 180 200 220 240 260 280 300 320 340 36(
I t

FLOW 11@@ M. G. D.

0 Stream Max. Min*

Inarajan 1100 .64

-NORMAL CUR E
.0017-

DRY CURVE

0 10 20 30 40 50 bo 70 so 90 Ic

USGS Sta. 8350 Percentage of Time FIGURE
Elevation 251+ 102

Measurements. The flow duration curves and data are shown in
figure 4-19., These measurement records show that the flows
vary from a maximum of 1100 mgd to a minimum of .64 mgd for a
period of record of 14 years. The Inarajan is. measured at
guaging station #8350, located approximately a halfmile above
its mouth. The average flow is 11.2 mgd. The headwater
locations for the Inarajan River fall on two major
tributaries. The first is located 2.7 miles upstream from
Inarajan Bay on the Pasamano River. The other is located .4
miles upstream from the confluence of the Laolao and the
Inarajan. 26

Power/head characteristics. The majority of the Inarajan
drainage area lies at elevations above 100 feet. The
configuration of the tributaries, however, is such that the
stretches of high flow have a low gradient. There are three
major tributaries which join the network about a mile apart
from each other. The first joins the network at the headwater
location on the Pasamano River, very near to the 200 foot
contour and is the farthest upstream tributary. The other two
tributaries join the Inarajan network inside the 60 foot and
40 foot contours. As a result, where there is higher head
potential (25 to 50 feet) there is the smallest flow, and
where there is high flow, there is little potential to develop
heads over 2 to 30 feet. If a penstock were dropped down far
enough at the Pasamano headwater to develop 160 feet of head,
then the instantaneous theoretical power potential would be 73

103

kW (assuming q = 5 cfs; e = 80%). This would require over a
mile o f penstock at a cost of about $40.00 per running foot,
or a cost of approximately $211,000.013 for penstock alone. If
the Pasamano and Yledigao, the next.tributary, where joined by
diverting one of them then approximately 123 kW could be
generated (based on the same efficiency, head, and
approximating the flow to be *8.5 cfs based on the combined
drainage 'areas). This kydro strategy, which i .sdiscussed in
Chapter II.C..4, is only applicable in special cases and is the
worst strategy in terms of economic and. environmental

considerations. . Should the cost of oil continue to escalate,

however, many such alternatives will emerge as viable due to

the inflationary oil costs.

The U. S. Army Corps of Engineers have targetted a

potential impoundment area on the Inarajan River at its

confluence with the LaoLao River. Based on Army data, the

maximum theoretical instantaneous power generation at the

proposed am woul d be 76 M This is calculated based on a

head of 102 feet, a flow of 5.17 mgd and an efficiency of

85%. Assuming the power plant would use only the water
discharged to maintain streamflow, 0.3 mgd), the generation

potential drops to 19 M

As is the case with most of Guam's streams, there are

many locations in the drainage system which could support a

small farm or home generation plant in sizes of 2 to 10 kW,

providing a suitable impoundment area could be located with

access. The best head/flow combinations for this would be on

104

I
I sections on both the Pasamano and Yledigao Rivers from the
I headwater locations down to the proposed dam on the Inarajan
main body.
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1 105

G. Geus River

Drainage area = 1.5 sq mi

The Geus River basin is N
located on the southwestern
tip of the study area and is
comprised of a single main
body fed by several springs
which maintain the flow in
the dry season. The village
of Merizo is supplied its
present water supply from
this river, just below
Siligin Springs, the largest
group in the supply
system.27 THE
STUDY
WAYGUE AREA

TATCUA

ASAW rON TE

APRA HARBO
J43
34

AGUADA
PAGO Geo-phyisical notes for the
PAVLAWA Gues River Fa@sin.
cAvTALI
APLA C. MA
General - mountainous land
YLIG underlain by lava flows,
breccia, and conglomerate.
AYUG& Upper reaches - steep gradient
flowing through narrow,
steep walled valley.
I'M ILI TOGCNA Lower reaches - gentle
TALOPOPO gradient flowing through a
%A U narrow flat valley
underlain by alluvium.
Point of discharge - Cocos
..."FAN 0, Lagoon southern tip of
28
Guam.

rAuLILUC
%IUAI&C

INARAJAN
JOGUAN

%t 14
'4"

-N.

106

DRAINAGE
AREA BOUNDARY
i uk--Zf@

00\1 300 50

v ao
"'-GE6S A,-
-100
0

'00
%,j

'000

\JV

DURATION DISCHARGE CURVE

Gr-us RIVER 11"EAR MERIZO

Record 14 Years
1952 1967

Period of Record D;schar.gc Equal to or -Excccding - in Mi. G. D.
518S Days 25 1 15 10 7 5 " I z 1 1.-5- 1 1. 01 0. 61 0. 41 0. 2 1 0. 11 0. 0
(Partial Years Included), 56 1 116 202 281 396 650 1 95@ 11242 18 -@, 1 26691 3Z?31 41201 47851 51U;
No. of davs in Drv Yr.x,l 3 1 5 1 10 101 15 22 32 41 59F 106F 1521 1921 2?8 1 365
Percentacc of time 0. 8 1- 174-1 2. 7 2.7 4. 1 6. 0 8. 8 13- 1 it, 2 29. ()1 41. 61 5-1. 6 1 62. 551 100
No. of davs in Av. Yr. 3. 9 8. 2 1 14. 8 7. 8 44' 5. 7 167. 0 S 7. 4 1 1. 2 9. 7 1 P, 7. E; 12 2 (,. 7 12 8 9. 8 11,1,6. 6. 6 5. 0
xgc of time 1.
9. 8 2
19
2. 2 1 3. (HI 6' 12. 5 18. 4 23. 9 1 3 5. 5 1 51. 1 1 62. 1 F17 9. 4@ 9?. 2 100
Percent. 5. 1 7 6 F I ', 5 8.
*Fiscal Year 65-66 Days in Year
20 40 60 80 100 120 140 160 180 200 220 240 260 260 300 320 340 11 61(

T N/. G. D.
@@ -- x - I :M i
7. 0 St r eLrn T

Geus i900 0

-4

'\'OR'.\4.-^. L C U, R VE

0. 8

0. 6

I i0o, I I NJ I 1 1
1DRY CURVE:06--@,, I F

0. 2
;;Z4

0 i F -I I I I I I I I i I I I i I I I I I
io 20 30 40 z C) 00 70 0 36 1
USGS Sta. 8210 Percentage of Time -,7 C! Tr R E
Elevation 851+ 108

Measurements. The flow duration curves and data for the Geus

River area are shown in figure 4-21. These measurement
records show that the flows vary from 1900 mgd to 0 for a
period of record from 1952 to 1967. This data was recorded
at guaging station #8210, located about one mile upstream from
its mouth. In a normal year the river basin produces less
than .25 mgd for 25% of the year, compared with a drought year
during which it is dry for 23% of the year. The average flow
at station #8210 is 1.95 mgd. The headwater location is set
by the Army Corps of Engineers at a point .32 miles downstream
of the guaging station. 29

Siligan Springs produces .030 to .020 mgd, and supplies
Merizo with part of its domestic water supply.
Power/head characteristics. Due to the low flow ratio for
this system combined with the fact that it has already been
developed as a water supply source for Merizo, it is a low
priority candidate for hydro generation. There are sections
of the river beginning at the 200 foot contour down to the
headwater location that could yield heads from 30 to 50 feet,
but the power generation potential is limited to small
applications of less than 12 M -This is an upper limit
estimate considering the fact that as Merizo's water demand
increases the downstream hydro potential decreases.

109

H. Umatac River

Drainage area 2.1 sq mi

Located in the southwestern
section of the study area
the Umatac River drainag;
area is composed of the main
Umatac River and its two
major tributaries, the Laelae
and Madog River. These
rivers join to form the
Umatac River .24 miles
upstream from its mouth at
Umatac Bay.30

THE
STUDY
ATGUE AREA

TATGUA
APRA HARBOR ASAM FONTE

ArUAOA
PAGO.

PAUtANA
GAUTALI Geo-physical notes for Umatac
APLACHA River basin.

YLIG General - mountainous lands
AYUGA underlain mostly by lava
flows and assorted
limestone beds.
y0GCMA Upper reaches - steep gradient
with stream fed by small
JALOFOFO
seeps and springs issuing
3kGU from lava flows.
Lower reaches - gentle
IIADOFAN gradient in a valley flat
ASUAFINES underlain by alluvium.
Point of discharge - Umatac
Bay southwestern coast of
PAULILUC GuaL31

INAMAJAN
JOCUAM

4 A CPA rA
It 14

110

DRAINAGE
AREA BOUNDARY
.-71@@ .. ... ... ...

300
.. .. ........
2OG

0
UMATAC
B Ay

Q.
........ ..

.... ..... ...
...... ... . ..........
@7

..........
'o

0
cl

. ... ......
0 0
0 . ......
0
r ?0.
rN
30 Moor,
80
0

Z 0
POINT OF DEVELOPMENT .00, 0
(COORD. IN METERS) .000
N 30. 911
E 41.488 N-401@>

UMATA

DURATION DISCHARGE CURVE

UMATAC RIVER NEAR UMATAC

Record 14 Years
1952 1967

Period of Record Discharge Equal to or Exceeding - in G. D.
5406 Days 25 15 lof- 71 51 31 21 1.51 1. 0 0.6 0. -;1 0. ?1 0. 1 1 o. 0
(Partial Years Included) 217 379 591 923 11339 ?2251 290-;j 34101 3966 48001 52891 53851 r.;061 54o6
No. of davs in Dry Yr.* 8 12 25 38 52 F-901 1361 3681 188 2,141 32d 1481 ,651 ' 365
Pcrccntape of time Z. 2 3. 3 6. 8 10.4 14. 2 1 74.71 37. 31 46. 01 51. 5 69. 61 87. 91 95. 3 1001 10 G
No. of davs in Av. Y r. 14.7 25.6 39. 9 1 6Z. 3 90.4 1150. 21196. 11?30. 2 1267. 81324. 1 1357. 111,63. 613,65. 01365. 0
Percenta-.Qc of tir-ne 4. 0 7.0 10. 91 17. 0 124.8 1 41. ZF5-3. 71 63. 11 73. 4 1 88. 81 97-91 99. 61 1 00T 100
*Fiscal Year 65-66

Daysin Year
20 40 60 80 100 120 10 .160 180 200 220 240 260 280 300 320 340 3 6

Lo W 2@ M. G. D.
9. 0-1 -1 1 T7 SI ream M'. M in.
4+
U rnatac 48zo .13
TT
6. o

3, 0 -F I I I i

Z. 5- T T T
INORMAL CURV---
T
ALj

T DRY CURVE
14
1. 5 N-11,

1. 0

i 1 11 i I I-T F, Fi@
0.57 1 J I I I I I I I I I I I I i -I I I I I I

.1 1 1 1 FT I I
@7'

.J-0
0 1 1 11
10 20 30 40 zo 00 70 90 16
USGS Sta. 8160 Percentape of Tirn 0
Elevation 12'+ 112

Measurements. The flow duration curves and data for the

Umatac River are shown in Figure 4-23. The measurement
records show that the flows vary from 4830 mgd to .13 mgd for
a period of record of fourteen years from 1952 to 1967. The
average flow measured at guaging station #8160, is 5.62 mgd.
The Umatac has one headwater location on the Madog River, a
major tributary. This is located .38 miles upstream from
Umatac Bay- 32

The bulk of the low flows come from the right branch
based on miscellaneous measurements of this stream. Even in
three low flow periods the base flow in the Umatac and its
tributaries is maintained by the numerous small springs and
seeps in the upper reaches of the river basin. The largest,
Piga Spring, supplies the village of Umatac with part of its
domestic water supply. 33

Power/head characteristics. Over a third of the river bodies
in this basin lie at elevations of less than 100 feet. The
remaining sections climb to an elevation of 300+ feet where

the streams originate.

The elevation at the guaging station is about 12 feet.
This section of the river continues downstream at a gradual
fall. As in the case of the Pago River, any head over 5 to 10
feet would have to be developed artificially at the dam.
Above the guaging station where the river tributaries
branch apart, the average flow is divided and there is
inadequate flow to support any sizable hydro installation.
The head/flow combinations are adequate to support a 5 kW

113

plant about 10% of the time, but the cost feasibility is bleak

except in special farm cases where off-season labor might be
used to deter the substantial cost of' civil works requirements

using farm resources. These factors combined with the fact

that the water is already being diverted to supply Umatac
makes this a low priority basin in terms of hydroelectric

development.

1. La Sa Fua River.

Drainage area = 1.2 sq mi

Located in the western
section of the study area,
the La Sa Fua drainage area
is composed of the main river
body and several high
elevation tributaries.
Although this drainage area
is small it is noteworthy due
to its consistently steep
gradient which allows
substantial natural heads.34

THE
STUDY
u&TCUE AREA

7ATGVA

ASAM F ONTE

APRA HARBOR JIT,
4J4

AGUADA
FAULANA PAGO, Geo-physical notes for La Sa
rA UTALI
APLACHA Fua River basin.

YLSO General - flows in a rugged
AYUCA narrow gorge of eroded
volcanic rock consisting
mainly of lava flows. The
TOGCNA River base flow is
maintained by numerous
7ALOFOFO smal 1 seeps and springs,
S.ru the largest of which, the
Alatgue Spring, discharges
normally 40,000 gallons per
SO day.
Fouha
Point of discharge
Bay southwestern coast of
PAVLOLUC GuaL35
%)U A-T&C
JOGUAN INARAJAN

U it 14

115

X.
66 '190

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

... .......

X
00 ... ... ...
9...
1100
X. 66

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

x..

DRAINAGE
AREA BOUNDARY

70
0
60Q :-..Q

..........
'to

500
..........
X.

'.00
100

POINT OF DEVELOPMENT
CT@. too (COORD. IN METERS
200 300 N 3 1, 914
FOUHA BAY 00 E 41,482

1000

300

LA SA FU

DURATION DISCHARGE CURVE

LA SA FUA RIVER NEAR UMATAC

Record 7 Years
19.52 1961
Discontinued July 7. 1961

Period of Record Discharge Equal to or Exceeding - in M. G. D.
2645 Days 25 is 10 71 51 3 2 - 1. 5 1. 0 0.61 0.41 0.2 0. 11 0. 0
(Partial Years Included) 34 83 129 187 7-73 447 667 874 1214 16201 2054 2608 2645 2645
,NO. of days in Drv Yr.* 2 11 18 27 39 57 87 118 168 2061 239 3491 366 366.
Percentage of time o. 6 3. 0 4.9 7.4 10. 7 15. 6 23.8 32.2 45.9 56.31 65. 3 95-41 100 100
No. of days in Av. Y r. 4. 7@ 1=1 . 5 17.8 25.8 37.7 61. 7 92.1 120.6 167.5 2 2 3. 6 12 8 3. 5 13 5 9. 9 1 3 6 5. 01 3 6 5. 0
Percentwge of time 1. 3 3. 1 4.9 7. 1 1 10. 3 16. 9 Z5.? 33. 01 45. 91 61. 21 77. 71 98. 61 1001 100
*Fiscal Year 59-60

Days in Year
20 40 60 80 1 0 120 110 160 180 200 220 240 260 280 300 320 340 6C

FLOW LNT M. G. D.
7.0 Strearn. Max. Min,

La Sa Fua 600 .11

5.0-

3, 0
01. 0 +71- --'F+ji'i W

tw)
I
0.8
u

NORMAL CURVE

o.6

D Y CURVE

0.4-

Li --- Ii-SA
0',

0
0 10 20 30 40 50 60 70 bo 90 ic
USGS Sta. 8010 Percentage of Time Tj
Elevation 1301+ 117

Measurements. The flow duration curves and data for the La Sa

Fua are shown in Figure 4-25. These measurement records show

that the flows vary from 600 mgd to .11 mgd for a period of

record of 2,645 days from 1952 to 1961. The average flow

recorded at guaging station #8096 is 2.57 mgd. One headwater
location is targetting on the Army Corps of Engineers map,

just downstream from the guaging station and .5 miles from the

mouth of the river. Because the stream has sustained base

flows in excess of .25 mgd for 95% of the time it has been

recommended as a site to augment the Umatac treatment plant
during the dry season. 36

Power/head characteristics. Approximately 94% of the La Sa

Fua drainage are is at an elevation in excess of 100 feet.

The river basin lies in a steep gradient with the upper

reaches of the stream originating at elevations of 900+ feet.

Since the river has relatively low average flows, it
could not be developed for large hydro applications. Also,

the development of the stream to augment the Umatac treatment

plant as mentioned above would further diminish the hydro

potential.

The stream does have a steep gradient, and falls from

the prospective point of development at an elevation of over

300 feet to sea level in less than 2.5 miles. From the 200

foot contour a straight line to the intersection of the river

and the 100 foot contour is less than .3 miles distant. This

means that heads of 50 to 75 feet are available with a minimal

penstock requirement, making this section particularly

attractive for a small, 5 to 7 kW plant, provided a suitable

impoundment area could be located.

The last two major drainage areas are mentioned not

because of their size but because they have sustained flovis

during low flow periods. For this reason they have been
considered for domestic water sources. Also, they have
stretches with steep enough gradients to allow enough natural

head to support small scale hydro plants.

119

J. Cetti River

Drainage area = 1.8 sq mi

Located in the western
section of the study area
the Cetti River drainage area'
lies immediately north of the
La Sa Fua drainage area. It
is a small drainage area
composed of two main branches
which intersect less than
1,000 feet upstream from the
point of discharge, Cetti
Bay.37

THE
STUDY
MATruE AREA

7ATGUA

---1 ASA 14 FONTE
APRA HARBOR 'T4 .7
44

AGUAVA
PASO

rAULANA
CAUTALf Geo-physical notes for Cetti
APL& C: KA
River Basin

YLIG General - similar in
AYUGA topography and geologic
features to those of its
neighbor, the La Sa Fua
'WLE ToGCMA drainage area.
Point of discharge - Cetti
TALDFOPO
U Bay 3ruthwestern coast of
GuaL

A00FAN
ASMArimE$ IS

PAULILUC

INAMAJAM
70GUAW

14
-14

120

X
0

120

110

DRAINAGE 0
AREA BOUNDARY

500
40
30
20
too,'*-\.,

800

2oo

A, too 1110

00
50
CETTI 001
BAY

1000 0 1000 2000

SCAU IN FEET
CON-TOURS IN FEET
"00 @l

CETTI RIVER DRAINAGE AREA

121

DURATION DISCHARGE CURVE

CETTI RIVER NEAR UMATAC

Record 7 Years
1959 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
2696 Days 25 15 10 7 5 3 1 2 1.5 1. 01 0. 61 0. 4 0.21 0. 1 0. 0
(Partial Years Included) 48 88 141 207 281 485 695 909 13111 17051 21091 251381 2660 2696
No. of davs in Dry Yr.* 4 7 8 14 19 42 55 72 961 1?91 1811 2871 362 365
Percentare of time 1. 1 1.9 2. Z 3. 8 5. _2 1 11. 5 15. 0 19.7 26. 31 35. 31 41). 6 78.61 99.21 100
No. of davs in Av. Y r. 6. 5 11.9 19. 1 28. 0 38. 0 1 65. 7 1 94.1 1123. 1 17 7. 5 12 30. 9 1 2 8 5. 51 34 3. 6 13 6 0. 1 13 6 5. 0
Percentape of time 1. 8 3. 3 5. 2 7.7 1 10. 4'1 100
*Fiscal Year 65-66

Days in Year

20 40 60 80 @l 0 120 140 160 180 200 220 240 260 280 300 320 340 116(

F LOW rN M. G. D.
7.0 Stream Miax. I Min.

Cetti 914 .02

5. 0

3.6 F FF -j -T--]- I I I I I
1.0 +4 H1 +

NORMAL CUR VE

o. 6

DRY CUR E

0.4

I I TIN"

-4
0
?-I-T-I T I I

0
1- Ll I I I I I I I I 1 -1 1 1
0 10 20 30 40 50 bo 70 so go I

USGS Sta. 8094 Percentage of Time
Elevation 101+ 122

Measurements. The flow duration curves and data for the Cetti

area are shown in Figure 4-27. These measurement records show

that the flows vary from 914 mgd to 0 for a period of record

of 2,696 days from 1959 to 1964. The average flow recorded at

guaging statin #8094 is 2.87 mgd. Ninety percent of the time

the flow of this river is .26 mgd. There is no headwater
location targetted by the U. S. Army Corps of Engineers. 39

Power/head characteristics. Due to the low average
streamflow, the Cetti River has very limited hydro potential.

The north branch of the river occupies about half of the

drainage area and consequently the flow is estimated to be

approximately 1.4 mgd at its intersection with the south

branch. This flow is coupled with heads in the order of 20 to
25 feet which could produce 4 to 5 kW of power, enough for a

small farm application.

Unfortunately, the sections of maximum flow lie on the

bottom, low gradient sections. In the upper reaches, the high

gradient sections, the river falls from the 600 foot contour

in the North branch to the 100 foot contour within 1,400
feet. In this section low flows could combine with these high
heads using impulse wheels of Pelton turbines to generate

between 4 to 6 kW provided a suitable impoundment area could

be located.

Because of the low generation potential, the Cetti is
still a low priority area for development. Contributing to

123

I
the negative argument is the fact that the Cetti River lies I
far from centers of population and -the storage capabilities I
are small.
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1
124 1

K. Finile Stream

Drainage area = .3 sq mi

Located in the western
section of the study area,
the Finile River drainage
area lies just south of the
village of Agat. This small
drainage basin is mentioned
because its gradient it is
quite steep and is near a
point of use.40

THE
STUDY
AREA

'FATCUA
APRA HARBO *3A FONTE
3434

ACUAV&
PAGO

I AUL A W A
C; A" 'AL
AILA N A

TLIG

AY U G A,

70(;CMA

7ALOPOfO

IAIU

WADOFAN

AS.AFIMfS
C.

C P A U L I L U C

J A x
TOGUAN AC FA),,

125

4U
co
4v LEGEND

'T OWNERSHIP
RECOMMENDED GOV
DRAINAGE FOR DEVELOPMENT
AREA BOUNDARY
RECOMMENDEDGOV'T. CONTROLLED AREA
WITH RESTRICTED RIGHT OF ENTRY

FIN
IL

. . . . . . . . . I

POINT OF DEVELOPMENT
(COORD. IN METERS)
N 3 9, 518
E 40,098

1000 0 1000 2000

SCALE IN FEET
CONT OuRs IN FEEr
'0000

FINILE RIVER DRAINAGE AREA

126

DURATION DISCHARGE CURVE

FIINILE STREAM AT AGAT

Record 7 Years
1959 1967

Period of Record Discharge Equal to or Exceeding - in M. G. D.
2647 Days 25 15 10 7 5 31 2 1. 5 1.0 1 0. 61 0. 41 0. 2 0. 1 1 0. r,
(Partial Years Included) I Z 9 24 41 118 z ?-- 81 36' 711 14?8 1831 2296 2595 2647
davs in Dry Yr.* 0 0 0 1 1 6 -F- 106 i49 2451 336 365
X - 11 20 38
Percentage of time 0 0 0 0. 3 0. 3 1. 6 3. O-F 5. 5 10.4 29.01 40.81 A7 1 1 Q?- 0 100
, 0, o'

No. of davs in Av. Y r. 0 1 0. 3 1.2 3. 3 5.7 16. 3 M.4 50. 2 198.0 1196. 9 1752. 41316. 6 357. 8 365.0
Percenta@@ze of time V
*Fiscal Year 65-66 0. 0 0. 1 0.3 0. 9 1 . 4. 5 8. 6 13.7 126.9 1 53. 91 69. 21 86. 71 98. 01 100

Days in Year
20 40 60 8 1.00 120 140 160 180 ZOO 220 Z40 260 280 300 320 340 36C

F LOW INT M. G. D.
Stream M;i-- Min.
7.

Finile 205 o6

5. C

3. 0

1. 0

I J

NORMAL CURVE

DRY CURVE

0. 4

0. 2
FFL,

0 1 1 -FT7 -i 1 1
0 10 zo 30 40 50 60
70 60 90

USGS Sta. 8083 Percentage of Time FIGU RE:
Elevation 201+ 127

Measurements. The average flow of the Finile creek is .92

mgd- Ninety percent of the time the flow is .13 mgd. This is
measured at gauging station #8083 (fig. 4-29). The record for
this station shows that the flows vary from 205 mgd to .06 mgd
for a period of record of 2,647 days from 1959 to 1967. Based
on this record, a flow of .2 mgd can be expected 65% of the
time, even during drought years such as 1965 to 1966. 41

Power/head characteristics. Like the Cetti, the Finile has
low flow and consequently low hydro power potential. Also,
like the Cetti, the Finile is a relatively sure source of
water and in a normal year could be expected to deliver .3 mgd

roughly 75% of the time. This means that a small installation

say, 2 W, could be developed and generate power most of the
year. Heads from 25 to 40 feet could be developed just
upstream from the guaging station as the station elevation is
about 20 feet and the 100 foot contour is within 1,000 feet.
On the negative side, the Finile basin has been described in
technical surface water studies as being too steep for
practical ponding or storing stream water.

L. Other Drainage Areas and Springs

Eleven drainage areas have been thoroughly described
above. These were described first because they are al I the
major candidates for development of surface water for domestic
use. Consequently, these water bodies have the most complete

128

data base, and have been studied for potential impoundment

areas and water sales. Recommendation!; of land mass purchase

necessary to development have been made and are shown as the

shade d areas in the drainage area maps. As a resul t, they are

considered to be the most developable basins.

There are many other spots on Guam's rivers which could

support a small farm or home hydro application in sizes Up tD

10 M Small hydro installation are futher addressed in

Chapter II.C.5, Hydro Strategies, under "Small Scale

Applications".

M. Springs

In the study area there are numerous springs and seeps

which help maintain the base flow of the various streams.

Many have been addressed within the discussion of the drainage

area of which they are a part. The more productive springs

such as the Alamagosa, Bona, Alatgue, Fliga, Siligin, and Santa

Rita are currently being tapped for military or local domestic

water, and have been already addressed in this report. There

are also two other springs, Asan and Agana. Springs, that are

located within the study area.

Asan Springs provides domestic water for the village of

Asan at the average rate of about .3 mcid. The overall average

production of this spring is .5 mgd at an elevation of 140

feet. The flow of this spring varies seasonally from a low of

.1 mgd to a wet weather high of 1 mgd. Although approximately

129

7 to 10 kW of power could be generated from this source if a

penstock were run down to sea level, it is unlikely that it

would be developed as the Government of Guam is already using

the spring water.

The Agana Springs are located on the edge of the Agana

swamp and have been a source of domestic water since before

World War II. The springs have a wide seasonal fluctuation in

flow and lacks any developable head required for hydro

development, but has yielded an average of 1.5 mgd as a

domestic water source.

130

NOTES FOR CHAPTER IV

I. Austin, Smith & Associates, Inc., A Report Covering the
Surface Water Survey of th land ot Guam
Public Utility Agency of Guam Report, Agana, Guam
June 1968, pp. 11-12

2. Ibid.

3. Ibid.

4. Ibid., pp. 14-15

5. Ibid.

6. Ibid.

7. Ibid.

8. Ibid.

9. Ibid., p.17

10. Ibid., p. 17

11. Ibid.

12. Ibid.

13. Ibid., pp. 17-25

14. Ibid.

15. Ibid.

131

16. Ibid., pp. 25-27

17. Ibid.

18. Ibid.

19. Ibid.

20. Porter E. Ward, Stuart H. Hoffard, and Dan A. Davis,
Geology and Hydrology of Guam, Marianas Islands
Geological Survey Professional Paper No. 403-H
United States Government Printing Office,
Washington, D. C. 1965

21. Austin, Smith, & Associates, Inc., A Report Covering the,
Surface Water Survey of the island of Guam
Public Utility Agency of Guam Report,Agana Guam
June 19 68, p. 31

22. Ibid.

23. Ibid.

24. Ibid., pp. 31-33

25. Ibid.

26. Ibid.

27. Ibid., pp. 33-35

28. Ibid.

29. Ibid.

30. Ibid., pp. 35-38

31. Ibid.

132

I
1 32. Ibid.
I .33. Ibid.
1 34. Ibid., p. 38
1 35. Ibid.

36. Ibid.
I
1 37. Ibid.
38. Ibid.
1
39. Ibid.
1 40. Ibid.
1 41. Ibid.
I
I
I
I
I
I
I
I
1 133

I
I
I
I
I
I
I
I
I Chapter V
I
I
I
I
I
I
I
I
I
I

V. EXISTING WATER FACILITIES

It has already been mentioned that the amount. of

hydroelectric energy that may be generated depends on the
quantity of water available, the vertical distance the water

falls, and the ability of the power plant to use the flow.
Consequently, this study initially addressed the questions:
"How much head is potentially available?" and "How much water
is available in a source?" The next step is to discuss the

power plant itself and its ability to use Guam's available

water resources.

Hydraulic plants may be classified by the degree of

water-flow regulation they can exert. A run-of-the-river
plant has no control over the flow of the river, and uses it
just as it comes. The other extreme is a hydraulic plant with

water storage that allows it to compensate for high and low
flow periods by accumulating and discharging the stream
water. In either case, there are basic component requirements
that must be met for electrical power to be generated. These
are basic civilworks fundamental to any hydro plant liscussed
in detail in Chapter II, Hydro Strategies, and are as

follows:

1. A dam. Even in a run-of-river application a small
dam must be constructed to maintain the upstream.

water level and divert the water to the

135

powerhouse.2

2. A spillway. This is an important requ irement on

Guam where torrential rains create flow levels many

magnitudes above the average fl ow. The spi 114 ay

allows the floods or excess flows to pass around or
safely over the dam. 3

3. Outlet works. This is the part of the dam that

passes water to the downstream si.de from the reser-

voir and includes: an entrance channel; trashracks;

intake structure; waterway; water-control system;

bypass valves; access shafts, and bridges or tunnels
necessary for operation and maintenance. 4

4. Powerhouse. This contains the hydraulic

turbine/generator and a foundation for the
powerhouse. 5

5. Bypass works. These divert the water directly
downstream in case the turbine is not functioning. (5

6. A switchyard and transformer. This allows the

generator to be connected to the transmI ssion
7
line.

7. Environmental structures, such as fish ladders. 8

136

8. Temporary civil structures. UsLally if a dam is

constructed, a temporary or coffer dam is built to
divert the river during construction. 9

In terms of cost payback, it makes good economic sense
to utilize any existing structure that could provide the
function of, or defray the cost of, those basic civil

components of the hydro installation listed above. Since
there is no existing hydro installation that may be renovated
or reactivated, the next target to consider is Guam's existing
water facilities. Consequently, this section of the study
will discuss the potential of using any existing water
facility, particularly existing impoundme nt areas, as a

starting point for a hydraulic plant.

A. IMPOUNDMENT AREAS

There are four major impoundment areas in the study
area. These are the Asan Springs Storage Basin, the Santa
Rita Springs Sorage Basins, the Geus River Dam, and the Fena

Reservoir.

1. Asan Springs

Originally constructed by the U. S. Navy in 1929, the
Asan Springs Storage Basin initially included an uncovered

137

storage basin, a perforated conduit with gravity discharge

penetrating into the hillside, and an overflow spillway. Th e

basin itself has a storage capacity of about 30,000 gallons

resting in two storage compartments, ten feet deep. Si nce Its

installation, additions have been made, including a concrete

roof covering two vertical turbine booster pumps designed to

operate one at a time and to pump against the head suppli! d by
the Piti Reservoir. 10

Hydro power potential. The estimated discharge of this Asan

facility is 120 gallons per minute or .17 mgd. As this figure
indicates, only minimal theoretical power potential exists at

this source, about 170 watts, and certainly not enough to

economically justify diverting this source of water from the
Piti Reservoir. 11

2. Santa Rita Springs

Also constructed by the U. S. Navy in 1929, the Santa

Rita Springs facility is similar in construction to the Asan

Springs facility. It has two storage basins with a combined
capacity of 105,000 gallons. Water from the storage basins

flows by gravity to its point of use, the old Agat and Hyundai
subdivision area. 12

Hydro power potential. The estimated discharge of the Santa
Rita Springs is 50 gpm or .07 mgd. The springs are located at

138

the foot of a hill allowing little potential to develop head
immediately at the site. Like the Asan Springs facility, the
Santa Rita Springs and its impoundment area are used to supply
domestic water. The Asan facility uses the available head at
the site on the suction side of the pump which delivers the
water. Any available head at the Santa Rita facility is used
to provide the gravity flow to the domestic water point of use.
The minim al hydro potential at the Santa Rita facility
is-not economically developable.

3. Geus Dam

Approx imately 100,000 gallons are impounded behind the
Geus Dam, and old concrete dam and diversion structure. The

stored water is sand filtered and delivered to the
transmission main and then to the Pigua Booster Pump Station.
The dam is a small structure, less than ten feet high, and is
considered to be a marginally reliable source of water due to
13
dry periods.

Hydro power potential. The estimated capacity of the Geus
River Dam as a water supply is 70 gpm or .1 mgd. As in the
Asan and Santa Rita Springs cases, the combination of low
flow, low head potential at the immediate site, and existing
domestic water distribution systems which use available head,
make this site economically undevelopable as a hydro plant.

139

4. Fena Reservoir

Constructed in 1951 by the U. S. Navy for military use,

the Fena Reservoir is located in the Talofofo River Drainage

Area, and more specifically, in the Na.val Magazine. Fena Dam

is about 85 feet high, 1,050 feet -in 1ength and is stocked

from a six-square-mile watershed giving it a capacity of

approximately 2.3 billon gallons. The Fena Dam has been

addressed as a potential hydro site in Chapter III D under -the

Talofofo River Basin. That section includes a flow duration

curve. based on data accumulated at guaging station #8490,

which measures the water discharged over the Fena Dam

spillway That section also shows that the Fena Dam could be

augmented with a 135 kW power plant that would produce about

@27,000 kWh in a normal year. At $0.10 per killowatt, this

amount of energy would cost $32,700.00 per year. If that

amount was paid as a yearly payment to amortize a 20 year loan

at equal annual payments at 10% interest, it would support a

loan of $278,393.50 which would cover the power pl ant

installation cost (provided there was no excessive cost in (Jam

modification). As mentioned earlier, the power generated

could be used at the dam to help power the four 3,500 gpm, .300

horsepower pumps which are presently used at the reservoir to

deliver the water from the dam to the Fena water treatment
plant, three miles away. 14

The Fena reservoir has existing access roads which

140

could accomodate equipment necessary for construction and

refit. It also has existing electrical hookups on site which

facilitate generation.

There are other impoundment areas and clearwells in the

study area, such as the Ylig, but none with storage capacities

great en ough to be useful for hydro power generation, and none

as large as those discussed above.

B. WATER DISTRIBUTION FACILITIES

Once the domestic water supply has been treated it is

distributed by a system of the following components:

1. Booster pumps.

2. Pipelines.

3. Control valves.

4. Hydrants.

5. Storage reservoirs.

6. Service connections.

7. Meters.

This system provides the water at a usable pressure for
home and commercial use. This pressure range is normally
between 40 to 80 psi. In many cases the water must be
supplied to higher elevations to provide adequate service.
Guam's water distribution system was not designed and

141

built in one phase. It has evolved since pre-war periods,

adjusting to. new water demands. When originally designed,

energy was much cheaper and*no real design constraint. As a

result, investigation into the system design reveals energy

inefficiencies that are not cost effectively changed. For

instance, water is pumped from sources to high elevation

storage. Then the water flows from these high elevation

storage points, by gravity, to use points, frequently miles

away, at much lower elevations. The high head in these

situations effect pressure increases, that are alleviated by

pressure release valves.

An example of this scenario is the case of the

Barrigada Reservoir which supplies part of the Tumon Area. On

San Vitorius Road about 800 feet from Marine Drive, the

pressure release valves are located. They bleed the excess

pressure caused by the difference in elevation of Barrigada

Reservoir and the beach r0ad.

In the aggregate, these inefficiencie s sum up

substantially, but on a case by case basis are uneconomical to

remedy. It is unlikely that the entire water system will be

redesigned in the near future, and there is little

administrative emphasis on correcting minor energy losses

compared to the numerous water leaks in the system.

142

NOTES FOR CHAPTER V

1. Leslie M. Price, "Power From Water", Power, April 1980
pp. S.8-S.12

2. Ibid.

3. Ibid.

4. Ibid.

5. Ibid.

6. Ibid.

7. Ibid.

8. Ibid.

9. Ibid.

10. Barret, Harris & Associates, Inc., Water Facilities Master
Plan
NuUic Utility Agency and Environmental Protection
Agency Report, Agana, Guam, August 1979
pp. 4.18-4.35

11. Ibid.

12. Ibid.

13. Ibid.

14. Ibid.

143

I
I
I
I
I
I
I
I
I Chapter VI
I
I
I
I
I
I
I
I
I
I

VI. FURTHER ECONOMIC CONSIDERATIONS

A. WATER SALES

The study area, as a result of its geophysical

structure and population, is not self-sufficient in terms of

water supply and demand. It uses more water than it presently

produces, and consequently was the topic of study to see what

surface water systems could be developed to provide for the

present and future water needs.

At the time of this study, Public Utility Agency of

Guam customers spend $1.17 per thousand gallons of domestic

water. For a home, the total bill is usually under $15-00 a

month and represents no serious financial burden.

For a farmer who pays to irrigate, it is a different

matter, and his bill is many times the average home bill. For

this reason, a hydro installation may provide more than one

benefit. In addition to providing power, the system may

easily be designed to provide all of the farm water needs.

The yearly water bill may then be applied toward the yearly

hydro payments as a further cost hedge.

On a large scale, the Public Utility Agency of Guam

presently pays about $0.11 per 1,000 gallons to companies that

develop large water sources refered to in this study. This

figure follows a general inflation curve to accomodate for

increase in cost due to maintenance and operations and

provides the incentive to develop new water sources as demand

145

dictates.

To indicate the impact of this incentive, contrast the

water sales to hydroelectric development. First, consider -the

case of the developer w1ho owns a water-shed producing I mgd

90% of the time. The point of development chosen lies at '100

feet elevation in an average gradient section. At $0.11 per

1,000 gallons, the Public Utility Agency of Guam will pay -the

developer $36,135.00 the first year. If this amount is used

as an equal annual payment in a 20 year loan at 10% interest,

the developer can borrow $307,637.63 to develop the source.

Now, consider the same site but developed to produce

hydroelectric power. Assume his plant uses a steady 1 mgd.

This flow of water is available 90% of the time, and his plant

develops 20 feet of head at a plant efficiency of 80%. His

plant would produce a relatively constant 2.8 kW of power for

a yearly production of 24,589 kWh. To buy this power at $0.10

per killowatt would cost him $2,459.00 the first year.

Applying that as a payment in the above loan wou ld allow -the

developer to borrow $44,372.14 or a difference of

$263,265.49. Furthermore, the developer does not have to pay

for water treatment and pumping costs.

.This is the reason why existing sites that appear to be

good hydro prospects are not cost effective to change if thay

are being used as a source of domestic water.

Similarly, proposed sites at high elevations gain more

by using the existing head potential to deliver the water than

by generating electricit,v, particularly if the electricity is

146

to be used to deliver the water.

COST OF ENERGY

All of the calculations in this study are based on a
flat cost of electricity at ten cents per killowatt hour. It

is obviously inaccurate to insert this cost in a loan

amortization of 20 to 30 years at no projected increase$ b ut
since no one knows what will happen to the cost of electricity

on Guam, there is no alternative.

Historically, the unit cost of electricity doubled

between 1978 and 1980. If this rate of increase is used as a

basis for a life cycle cost analysis, the equation quickly
becomes distorted, particularly in view of the fact that this
cost is based on a fossil fuel generation plant. Alternatives
such as the Ocean Thermal Energy Conversion (OTEC) generation
scheme project unit costs of electricity of between $0.15 and

$0.20.

Anyone viewing a graph depicting the local rise of

electrical cost over the past five years (1975 to 1980) would
have to agree that the curve cannot realistically continue to
steepen, but that it must level off at some point. Unfortu-
nately, not everyone can agree on this point.

The Guam Power Authority projects an increase of around
10% to 15% per year. Obviously, this has not proven to be
historically accurate. One can safely assume that over the

near term, say the next five years, the unit cost of

147

electricity will increase between 10 to 20% per year.

This means that any potential hydro installation that

is within 10 to 15% of being cost effective based on an

electrical unit cost of $0.10 will surely be c ost effective in

the long term as the rising local cost of electricity steadily

enhances alternate energy prospects.

C. TAX INCENTIVES

The Crude Oil Windfall Profits Tax Act (COWPTA) of 1980

enacted other hydro incentives. One incentive is a Business

Energy Investment Credits provision., This allows credits of

11% for investments in projects at existing dams up to 25 MW

in size. Property that is eligible for the tax credit

includes all hydroelectric related equipment up to the

transmission stage. Included in this are generators,

turbines, powerhouses, and the rehab i 1 i tati on of dam

structures, plus fish ladders or passageways. The credit is

available through the end of 1985, with an extension through

the end of 1988 in the case of a lisence application docketed

by the FERC before 1986. This credit augments the existing
10% tax credit for alternate energy systems. 1

The COWPTA also makes fish passageways eligible for the

10% tax credit, and increases the use of the tax-exempt

industrial development bond as a financial mechanism for

hydroelectric projects. This tax exemption now extends to

those industrial development bonds where proceeds are used to

148

finance small-scale projects located at existing dams and

natural water features currently owned by the local
government. 2

D. LONG RANGE IMPACT OF HYDROELECTRICAL DEVELOPMENT

As a present alternative to fossil fuels, hydro

electric plants are more cost effective than OTEC, solar, wind

or biomass. Additionally, this technology has been proven for

centuries as a reliable, low maintanence form of generation,

with plant lifetimes of up to 50 years and longer.

Corresponding costs of generated electricity are,

consequently, almost static and provide the plant owner with a

real hedge against runaway inflation compared to commercial

utility costs that have doubled in the past two years (1978 to

1980).

149

No'rES FOR CHAPTER VI

1. IDAHO National Engineering Laboratory, Small Hydro Bulletin
U. S. Department of Energy, ReporY,-761. 2, No. T--
December 1980, p. 4

2. Ibid.

150

I
I
I
I
I
I
I
I
I Chapter VII
I
I
I
I
I
I
I
I
I
i

VII. CONCLUSIONS AND RECOMMENDATIONS

1. Hydroelectric generation is presently cost effective

at the best local sites. Those sites that are close but not

presently cost effective will become so within the next five

years.

2. Hydroel ectri c sites are attractive long-term
investments. Relative to the future cost benefits of a hydro
installation, history has proven this system repeatedly. The
author cannot predict the exact future cost of energy, however,
based on the current state of alternate energy research and
development in conjunction with the characteristic
administrative and industrial lags, energy costs will probably
rise in the next five years to a unit cost of between $0.15 to
$0.20 per killowatt. At this point several alternate system
and cogeneration possibilities could conceivably stabilize the
unit cost. There are always possibilities of technical
breakthroughs as happened at the turn of the 20th Century with
petroleum development which provided a brief respite from
escalating energy costs, but again hydroelectric projects were
proven economical even during this period and continue to
develop electricity.

3. There is an acute need for local i nf ormati on
generation and dissemination designed to promote the

152

development of small scale hydro systems in the range of 2 to

10 kW, As a followup on 'this and other studies.

4. There is a need for establishing recording guaging

stations at potential hydro sites., in order to accumulate

accurate design data. The lack of specific data restricts the

number of sites that may be evaluated. For instance, one h.ydro

scenario of very low-head hydrogeneration could not be

accurately addressed in this report. To d evelop any sizable

power using very low heads, large flow volumes are necessary.

On Guam, the downstream stretch of 'the Talafofo River, beyond

its confluence with the Ugum River, is such a location. This

section was investigated assuming an average combined flow of

50 mgd, and was determined not cost effective at current

electrical rates (SO.101kWh). Should the cost of electricity

increase over, say, 30%, then this site may be economically

developed.

Without accurately guaged data, however, it is

impossible to make any precise calculation, particularly when
the downstre am reaches of the Talafofo flow over permeable

alluvial soil which affects the ultimate discharge.

6. There is a need for the development of information

on related systems, specifically, hydraulic rams for pumping.

7. There is much that should be done to insure the

licensing process and other legal and environmental problems

153

are minimized for the prospective hydro installer. Federal

efforts are headed in that direction and the Guam local

government should definitely take a similar stance. As
mentioned in Chapter I, Legal Issues, the Federal Energy
Regulatory Commission (FERC) has freed projects with a capacity
of less than 5 MW that use existing dams or natural water
features from the Federal Power Act licensing requirements.
FERC was given the authority to exempt small hydroelectric
projects from licensing requirements by the Energy Security Act
of 1980. This legislation grants exemptions which free
developers from annual fees, inspections, and the threat of
Federal takeover. Furthermore, exemption applications are
automatically granted if FERC fails to act on them within 120
days.I

154

NOTES FOR CHAPTER VII

1. IDAHO National Engineering Laboratory, Small Hydro Bulletin

U. S. Department of Energy Report, Vol. 2, No. 4

December, 1980 p. 4

155

I
I
i
I
I
I
I
I
I Bibliography
I
I
I
I
I
I
I
I
I
i

BIBLIOGRAPHY

Austin, Smith & Associates, Inc., Master Plan Report: Guam
Water System Imerovements, Fiscal Year 1972 to 198T.-
Public Utility Agency of Guam Report, Agana, Guam,
May 31, 1971

Austin, Smith & Associates, Inc., Conservation Requirements for
the Preservation of Guam Water Resources
Public Utility Agency of Guam Report, Aga-na, Guam,
August 31, 1970

Austin, Smith & Associates, Inc., A Report Covering the Surface
Water Survey of the Island of
Public Utility Agency of Guam Me-port, Agana, Guam
June, 1968

Barret, Harris & Associates, Inc., Water Facilities Master Plan
Public Utility Agency and Environmental Protecti-o-n -Agency
Report, Agana, Guam, August 1979

IOAHO National Engineering Laboratory, Small Hydro Bulletin
U. S. Department of Energy Report, Vol. 2, No. 4
December, 1980

Morse, Fredrick T., Power Plant Engineering and Design
D. Van Nostrand Company, Inc., New York, New York,
May, 1948

Price, Leslie M., "Power From Water", Power, April 1980

R. M. Towill Corporation, Determination Headwaters of Streams
U. S. Army Corps of Engineers Report, Honolulu, Hawaii
September, 1978

Skrotzki, Bernhardt G. A., and William A. Vopat, Power Station
Engineering and Economy
McGraw Hill, New York,-New York, 1960

157

"Harnessing Energy in the Amazon", Engineering
News-Record, July 10, 1980, pp. 24-26
"Units May Slash Small Hydro Costs", Engineering News-
Record, January 25, 1979, pp. 21

Sunn, Low, Tom, & Hara, Inc.,Hydrological Study for Potential
Water Supply Reservoir, Ugum River,Territory of Guam
vironmental Protection Agency Report, Agana, Guam
March, 1977

U. S. Army Corps of Engineers, Ugum River Interim Report and
Environmental Impact Statement, Harbors and Rivers,
Territory of Guam
U. S. Army Corps of Engineers Report, Fort Shafter,
Hawaii; June, 1980

U. S. Army Corps of Engineers, Water Resources Development
U. S. Amy Corps of Engineers Report, Fort Shafter,
Hawaii; January, 1979

U. S. Army Corps of Engineers, Guam Comprehensive Study, Water
and Related Land Resources, Stage I Report
U. S. Army Corps of Engineers Report, Fort Shafter,
Hawaii; August, 1979

U. S. Army Corps of Engineers, Harbors and Rivers in the
Territory of Guam, Interim Report on Flood Control
U.S. Army Engineers District Report, Honolulu, Hawaii
August, 1975

U. S. Department of the Interior, Water Resources Data for
Hawaii and Other Pacific Areas
U. S. Geologic Survey Water-Data Reports HI-70-1
through HI-78-1

Ward, E. Porter, Stuart H. Hoffard, and Dan A. Davis, Geology
and Hydrology of Guam, Marianas Islands
Geological Survey Professional Paper No. 403-H
United States Government Printing Office, Washington,
D.C. 1965

158

I
I
i
i
i
i
i
i
i
. i
I
i
i
i
i
i
I
--- I
3 6668 1-4109 446E - 11 @
A&