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This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library.
For additional information about this document and the document conversion process, please contact WRDS at [email protected] and include the phrase
“Digital Documents” in your subject heading.
To view other documents please visit the WRDS Library online at: http://library.wrds.uwyo.edu
Mailing Address: Water Resources Data System
University of Wyoming, Dept 3943 1000 E University Avenue
Laramie, WY 82071
Physical Address: Wyoming Hall, Room 249 University of Wyoming
Laramie, WY 82071
Phone: (307) 766-6651 Fax: (307) 766-3785
Funding for WRDS and the creation of this electronic document was provided by the Wyoming Water Development Commission
(http://wwdc.state.wy.us)
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
EXECUTIVE SUMMARY
Prepared for
WYOMING WATER DEVELOPMENT COMMISSION
November 1984
.&-Stone & Webster Engineering Corporation
Approved:
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
EXECUTIVE SUMMARY
Prepared for WYOMING WATER DEVELOPMENT COMMISSION
November 1984
tOt.
14980.07 - H(D)-l
Project Engineer Division Head
ering Management
Copyright 1984 Stone & Webster Engineering Corporation
Denver, Colorado STONE Be WEBSTER A
No. of Copies
1
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INTERNAL DISTRIBUTION
Recipient
Director of Engineering, Boston - Philip A. Wild
Engineering Manager, DOC - R. J. Conlon
Hydraulic Division Manager - D. L. Matchett
Geotechnical Division Manager - D. L. Matchett
Technical Information Center, Boston
Technical Information Center, DOC
D. H. Rutherford
G. C. K. Grinnell
R. Mascolo
R. D. Reynolds
M. L. Barningham
Western Water Consultants, Laramie Wyoming
Western Research Corp., Laramie, Wyoming
Robert Jack Smith and Associates, Rawlins, Wyoming
W. W. Reedy, Denver, Colorado
Dr. R. B. Peck, Albuqurque, New Mexico
STONE Be WEBSTER A
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
EXECUTIVE SUMMARY
PREPARED FOR
WYOMING WATER DEVELOPMENT COMMISSION CHEYENNE, WYOMING
WALTER J. PILCH Chairman
JAMES NOBLE Vice Chairman
WILLIAM J. KIRVEN, JR. Secretary
LEWIS FREUDENTHAL
KENNETH KENNEDY
J.W. WES' MYERS
WILLARD C. RHOADS
MERL RISSLER
NELSON E. WREN, JR.
MICHAEL K. PURCELL
Administrator
PREPARED BY
.&. Stone & Webster 'JI"i Engineering Corporation
DENVER, COLORADO
NOVEMBER 1984
STONE Be WEBSTER A
INTRODUCTION
This document provides a Summary of the study results on the Little
Snake River Water Management Project (LSRWMP) located in South Central
Wyoming as conducted by Stone & Webster Engineering Corporation (SWEC)
under the direction of the Wyoming Water Development Commission (WWDC).
More detailed information on the study can be found in the Technical
Summary Report dated November 1984.
The Wyoming Legislature by W.S. 41-2-121 authorized the WWDC to
prepare a report recommending a project configuration, providing a schedule
for implementing the project and project components, and furnishing an
estimate of construction cost for development of the LSRWMP. SWEC was
commissioned to examine project alternatives which best satisfy the
conditions set forth in legislation, comply with criteria established by
the Commission, and best conform with sound engineering and economic
considerations. Three major development alternatives were to be considered:
• Alternative C A gravity collection system extending the
Cheyenne Stage III collector across the Continental Divide into a
regulating reservoir on Sage Creek with a transmission pipeline
to the North Platte River.
• Alternative D - A storage reservoir(s) in the Little Snake River
Basin and a trans-basin pipeline with pumping stations to deliver
water from a diversion point near Baggs to the North Platte River
near Sinclair.
• Fish Creek Alternative - A collection system as in Alternative C
but storing the water in Fish Creek Reservoir located on the west
side of the Continental Divide and transporting the water by
tunnel or pumping into the North Platte River Basin.
The firms of Western Water Consultants, Inc. of Laramie and Sheridan
Wyoming, Western Research Corporation of Laramie, Wyoming, and Robert Jack
Smith and Associates, Inc. of Rawlins, Wyoming were a part of the study
team. Dr. Ralph B. Peck and W. W. Reedy served in an advisory capacity.
-1-STONE Be WEBSTER ..
LEGISLATIVE REQUIREMENTS
The major requirements and considerations which were set down in
legis lation regarding the development of the LSRWMP, located as shown on
Figure 1, are summarized as follows:
1. Storage of at least 10,000 acre-feet on Savery Creek.
2. Storage of at least 50,000 acre-feet for use in the Little Snake River Basin.
3. A collection and the North Platte purposes.
conveyance system for transporting water into River Basin for municipal and industrial
4. Groundwater should not be considered to be an alternative to the Stage III water supply. There should be no condemnation of agricultural water rights.
5. Enlargement of Seminoe Reservoir or alternative North Platte River storage should be considered.
6. The first phase of the study should recommend one of the two basic Alternatives, C or D.
In that Alternative C when originally conceived did not provide any
storage on Savery Creek or in the Little Snake Basin, the most recent
legislation required that in-basin storage be added to this scheme of
development.
EVALUATION OF PROJECT COMPONENTS
At the beginning of the study, SWEC examined the major alternative
development plans to identify the basic components. These components are
shown on Figure 2 and described as follows.
Two collector systems constructed so as to gather and convey water
from melting snow fields high on the western s lope of the Continental
Divide were considered. 'They are:
1. The Sage Creek Collector which runs from the Stage III collection area in a northwest direction until its gravity pipeline crosses the Continental Divide and into the Sage Creek Reservoir.
-2-STONE 8: WEBSTER A
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LOCATION MAP
" •• w
N
o I Z S 4 5 MILEI , , , • I I
ICALE
LITTLE SNAKE RIVER
STUDY AREA
FIGURE
STONE Be WEBSTER A
GREAT DIVlDE BASiN
,~~
~ SAGECREEV GRAVITY LIN
-/ f \
/
\ STAGE III '/7""'~"" COLLECTION IAREA
I
( ~r~ ...
U'PPER SAVERY RESERVOIR~~ '-l.. ~.. . 1
I
o 5 ----- 10
SCALE IN MILES
15
HOUTT NATIONAl
20
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
LOCATION OF PROJECT COMPONENTS FOR ALTERNATIVE PLANS
FOREST
OREST
FIGURE 2
~ Stone & Webster Engineering Corporation
2. The Fish Creek Collector - which has an alignment slightly lower
vertically than the Sage Creek System and flows by gravity into
the Fish Creek Reservoir on the west side of the Continental
Divide.
Six storage sites which are capable of providing annual storage of
spring snow melt runoff were considered. Five are located in the Little
Snake Bas in. They are:
1. Fish Creek Dam on Savery Creek
2. Upper Savery Dam on Savery Creek
3. Sandstone Dam on Savery Creek
4. Pot Hook Dam on Slater Creek
5. Three Forks Dam on Little Snake River
6. Sage Creek Dam on Sage Creek, tributary to North Platte River
Transportation systems associated with the LSRWMP are the features
which convey water by gravity flow or by pumping from storage or diversion
points to delivery points in the North Platte River Basin.
Four general transportation routes were considered. They are:
1. Fish Creek to Sage Creek
2. Sage Creek to North Platte River at Overland Crossing
3. Sage Creek to Rawlins to North Platte River at Sugar Creek
4. Baggs to Rawlins to North Platte River at Sugar Creek
The feasibility of incorporating hydrogeneration to benefit the
project was considered. Since flood control and recreational development
were outside the responsibilities of the WWDC, they were not included in
the studies.
By evaluating each of the project components on a comparable basis,
the relative effectiveness of separate components were assessed.
Combinations of project components were assembled to provide various plans
that supply water to both the Little Snake River and the North Platte River
basins.
Some of the project components were judged to be mutually exclusive,
that is, construction of one would eliminate the need for the other. These
were:
Fish Creek Dam and Sage Creek Dam
Tunnel and pipeline from Fish Creek to Sage Creek
-5-STONE Be WEBSTER ..
Pipeline from Sage Creek to North Platte River at Overland Crossing and pipeline from Sage Creek to North Platte River via Rawlins and Sugar Creek
Upper Savery Dam and Sandstone Dam
Although the Baggs Diversion/Pipeline is an alternate to the
trans-basin collection systems, it can also provide water to other areas in
south central Wyoming if additional storage in the Little Snake River Basin
is provided.
Hydrology
The major portion of the flow in the Little Snake River and its
tributaries comes from snowmelt runoff in the months of May and June each
year. Those tributaries with headwaters near the Wyoming-Colorado border
in the Sierra Madre mountains contribute significantly more flow to the
Little Snake River than do those in the northern area near the Great Divide
Basin. For institutional and other reasons water could be passed through
or over the Continental Divide only at the north end of the proposed
collector system. Therefore, it was concluded that staged development of a
collector system would be neither practical nor economical and it would be
necess'ary to construct a collector system from the Stage III collection
area, carrying water northward into the North Platte Basin as a single
project. The Fish Creek Dam as a storage site for in-basin use was not
feasible without the added water produced by a collector system.
Construction of a collector system for in-basin use alone was not cost
effective.
The Sage Creek Collection System would develop an average yield of
38,300 acre-feet while the Fish Creek Collection System being slightly
lower with a larger drainage area could develop 47,600 acre-feet.
Simulated Operations Studies were conducted to determine the most
effective size of the various reservoirs, and to assess the effect of
storage on yields. The selected reservoir capacities and average yields,
taking into account the Stage III Fish Creek Collection system depletions,
are tabulated below. Firm yields shown are computed on the basis of using
a 50 percent agricultural demand, which is one-half cfs per 70 acres of
water right acreage (approximately one cfs per 70 acres of presently
irrigated acreage).
-6- STONE Be WEBSTER ..
Upper Savery
Sandstone
Pot Hook
Three Forks
Hydraulics
Reservoir Capacity
(acre-feet)
40,000
52,000
61,500
100,000
Average Firm Yield Yield
(acre-feet/yr.) (acre-feet/yr)
23,500 16,000
38,500 25,900
33,500 32,300
84,500 73,500
Project components governed by hydraulic design considerations were
sized for comparable operation criteria wherever possible. For water
exported via the Fish Creek and Sage Creek Collection Systems it was
considered that all available water could be used in the North Platte River
basin, since export capability appeared to be in the range of the
preliminary forecasted needs in the year 2030. The smaller yield of the
Sage Creek System would be totally utilized sooner than the Fish Creek
System.
While the addition of hydrogeneration to the project looked
potentially feasible at Three Forks, Sandstone and Sage Creek Dams, the
benefits from hydro installations, were not large enough to change the
general ranking of the preferred plan of development.
Geotechnical Aspects
Geotechnical evaluation of the six damsites, two collectors, and four
pipeline/tunnel conveyance systems was based on available information from
previous studies and field reconnaissance. Subsurface information was
available for four of the six damsites, Fish Creek, Upper Savery, Sandstone
and Pot Hook. With only one boring at each site, Three Forks and Sage
Creek sites were evaluated primarily from surface geologic information.
Resul ts of the geotechnical evaluation were incorporated into the
design concepts for the various features and are reflected in the
comparative cost estimates for each.
Review of the geotechnical aspects of the dams was provided by
Dr. Ralph Peck, an internationally recognized expert in the area of
embankment dams and geotechnical engineering.
-7- STONE Be WEBSTER A.
Environmental Considerations
Environmental studies were limited to the identification of possible
environmental problems of a magnitude and/or complexity that would severely
impair or prohibit the development of the proposed LSRWMP. Such problems
are not evident at this time. Necessary coordination with appropriate
agencies regarding the preparation of an Environmental Impact Statement
eElS) is recommended as a part of the WWDC Level III Phase II project
work. The EIS process will require the evaluation of project alternatives,
including the consideration of no action and utilization of ground water.
PLAN COMPARISONS
Near the beginning of the study, a methodology was developed that
would provide a framework for making comparisons in a thorough and
systematic manner. A progressive evaluation and screening process was
used, first to compare the various components and alternatives, and then to
eliminate those that appeared less attractive. Comparisons were subjective
with respect to environmental and institutional factors. Engineering
features of the components were developed to approximately the same
standards of constructability and safety. Costs then become the
determining factor in selecting between components that would serve the
same function, and ultimately in selecting the preferred plan.
Based upon evaluation of the Legislative, Environmental,
Hydrological, Geotechnical and Institutional considerations, the following
conclusions were reached:
• Fish Creek Reservoir is not a practical site considering
in-basin storage only.
• Pot Hook and Three Forks damsites are wholly or partially in
Colorado. Because of the significant additional legal and
administrative activities considered necessary to construct
either of these storage facilities, it is believed prudent not
to utilize them as near term project developments.
• Upper Savery damsite requires special design criteria to
accommodate the poor foundation conditions at that site.
-8- STONE Be WEBSTER A
COST ESTIMATES
Comparative cost estimates were developed for the various project
components which were identified in the study. They are summarized on
Table 1.
The least cost in-basin storage facility, Pot Hook, is located in
Colorado. Sandstone is the least costly site in Wyoming.
The Fish Creek Collection System is the most economical trans-basin
diversion system, due to its greater yield and lower cost. The free flow
or tunnel alternative from Fish Creek reservoir through the Continental
Divide, although slightly more costly, is preferred over the pumping
alternative primarily due to its increased reliability and flexibility.
The Baggs Diversion alternative when considered along with the least
costly in-basin Reservoir (Pot Hook) is not cost competitive with the Fish
Creek Collection System.
A summary of the estimated costs of six plans developed by selecting
various components of in-basin and trans-basin diversion facilities is
shown on Figure 3. The least costly plan, Plan 2, combines the Fish Creek
Collection System with Pot Hook Reservoir. Plan 2 requires dedication of a
portion of the collector system water to in-basin needs to satisfy
legis lative requirements and therefore, reduces water yield to the North
Platte River basin. It also requires the involvement of Colorado interests
to develop the in-basin Pot Hook reservoir.
Plan 1, which combines the Fish Creek Collection System with
Sandstone Dam and Reservoir becomes, therefore, the preferred plan for
development of the Little Snake River water resource.
-9 - STONE Be WEBSTER A
TABLE 1
Project Component Cost Summary
In-Basin Storage
Upper Savery Sandstone Pot Hook Three Forks
Trans-basin Diversion (45,000 acre-feet/yr.)
Fish Creek Collector Fish Creek Dam & Reservoir Tunnel & Pipeline to N. Platte River
Fish Creek Collection System
Unit Cost of Water = $3800/acre-foot
Pumps & Pipeline Pot Hook Dam
Baggs Diversion Pumping Scheme
Unit Cost of Water = $4245/acre-foot
Trans-basin Diversion (33,300 acre-feet/yr.)
Sage Creek Collector Sage Creek Dam & Reservoir Pipeline to North Platte River
Sage Creek Collection System
Unit Cost of Water = $7070/acre-foot
Pumps·& Pipeline Pot Hook Dam
Baggs Diversion Pumping Scheme
Unit Cost of Water = $5070/acre-foot
-10-
Estimated Cost ($ X 1000)
$ 65,400 61,300 26,300 73,900
94,300 26,400 50,200
$170,900
165,700 26,300
$191,000
183,500 24,600 27,400
$235,500
142,600 26,300
$168,900
STONE 8: WEBSTER A
IN BASIN STORAGE
THREE FORKS POTHOOK SANDSTONE
DAM AND DAM AND DAM AND RESERVOIR RESERVOIR RESERVOIR
COMPONENT ESTIMATED COSTS 73,900 26,300 61,300
($ x 1000)
PLAN t 61,300
PLAN 2 26,300
PLAN 3 26,300
PLAN 4 73,900
PLAN S 61,300
PLAN 6 73,900 61,300
TRANS - BASIN DIVERS 10 N
PUMPING COLLECTION SYSTEMS PIPELINES
IAGa CONYEYANCE PLAN
DIYERSIOtI TO COLLECTORS RESERYOIRS PIPELINES ESTIMATE
N. P\.ATTE R. ilATTL! CREEK COSTS
45.000 A/ft. 'ISH CREEK 'ISH CREEK
($ X 1000) -,tsH CREEK -N. Pt.ATTE R.
I6S,700 94,300 26,400 50,200
94,300 26,400 50,200 232,200
94,300 26,400 50,200 197,200
16S,700 94,300 26,400 312,700
16S,700 94,300 26,400 360,300
16S,700 2S3,300
16S,700 300,900
[J PREFERRE 0 PLAN
FIGURE 3
STONE Be WEBSTER ..
• o o .. • N -C
RECOMMENDED PLAN OF DEVELOPMENT
The preferred plan of development for the Little Snake River Water
Management Project consists of three prime components as shown on Figure
4. The plan provides for:
1. Sandstone Dam & Reservoir - In-basin storage for the Savery Creek and Little Snake River drainages.
2. Fish Creek Collection System - Out-of-basin transfer of water to the North Platte River drainage.
3. Baggs Diversion Pipeline with Pot Hook and/or Three Forks Reservoir - Future expansion facilities that provide flexibility to use the full allotment of Wyoming Compact water as a long-range plan for ultimate development of the Little Snake River basin waters.
SCHEDULE
The recommended LSRWMP schedule of development as shown on Figure 5
is to proceed immediately with the in-basin storage facility Sandstone Dam
and Reservoir. It is estimated that water storage could be achieved in the
spring of 1990.
Evaluation of the results of the WWDC work in progress that will
impact the Fish Creek Collection System should be continued. Preparation
of a conceptual design layout for the collector system with possible
alternatives should be undertaken. Pipeline routing to the North Platte
using the stream bed of Sage Creek for portions of the conveyed water as
well as a joint pipeline with the city of Rawlins should be investigated.
Such studies will provide the necessary data with which to evaluate the
environmental concerns and define field data collection to comply with
permitting requirements.
The ultimate plan of development should be pursued as necessary to
provide continuing dialog and cooperation with Colorado that will be
beneficial to the future development of Wyoming Compact water.
-12-STONE Be WEBSTER A
BUDGET
The budget for the recommended plan of development should anticipate
the permitting and design efforts for Sandstone Dam and Reservoir in 1985
and 1986, with construction expenditures beginning in 1987. Funding for
the further definition of the Fish Creek Collection System impacts and
utilization should be considered during the period 1985-1990.
-13- STONE Be WEBSTER A
"
GREAT
\
BAGGS TO NORTH PLA TTE PIPELINE
D!VIDE BASIN
\
\.._~C: N TIN £ N TAL l.._./\ .... //",;
c,... ..
SANDSTONE RESERVOIR
_ INITIAL DEVELOPMENT
_ ULTIMATE DEVELOPMENT
o 5 ----- 10 15
SCALE IN MILES
ROUTT
20 !
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
RECOMMENDED PLAN OF DEVELOPMENT
F 0 I, .E S T
NATIONAL FOREST
FIGURE 4
~ Stone & Webster Engineering Corporation
APPENDIX SUMMARY
NORTH PLATTE RIVER SUPPLEMENT
The North Platte River Management Model (NPRMM) is a computer program
which simulates the river operations which are coordinated by the U. S.
Bureau of Reclamation using the six storage reservoirs on the North Platte
River in Wyoming. Figure 6 shows the location of these six reservoirs
along the North Platte River.
As a portion of the LSRWMP Phase I work, a study of the currently
available NPRMM revealed that the model was incapable of accounting for
imported water from the Little Snake River Basin or quantifying possible
additional existing water resources in the North Platte River. A new
algorithm was developed to establish an additional ownership account
(Excess-to-Ownership). Several studies were performed using the revised
model and discharge records for the period 1940 to 1982.
The term "excess-to-ownership" refers to the amount of North Platte
River water that is available after all present ownerships are satisfied
or, simply, unappropriated water. By accounting for the "excess-to
ownership" water in the North Platte River, a firm annual yield of about
8,400 acre-feet can be obtained from an enlarged Seminoe Reservoir. A
yield of 9,600 acre-feet per year was found with only two out of 56 years
experiencing shortage.
There is sufficient remaining capacity in the existing Seminoe,
Pathfinder, and Glendo Reservoirs to regulate imported water from the Fish
Creek Collector system. An enlargement of Seminoe Reservoir is not
necessary to regulate the imported water, but it would make possible the
maximum utilization of the total water resources of the system.
The NPRMM has been a useful tool for evaluating the impacts of
importing water into the North Platte River Basin from the Little Snake
River. For future detailed planning, the model should include options of
where, when, and how much water will be imported. The quantity, timing and
diversion points for utilizing the imported water should be modeled as well
as the necessary conveyance loss estimates. The calculation of conveyance
losses below Guernsey Dam and the demands of private ditches below Whalen
-16- STONE Be WEBSTER A
LITTLE SNAKE RIVER LEVEL III PHASE I - SELECT PLAN
IN BASIN DEVELOPMENT
SANDSTONE DAM
ENVIRONMENTAL IMPACT STATEMENT
CONCEPTUALIZE
DESIGN
CONSTRUCTION
TRANS BASIN DEVELOPMENT
COLLECTOR SYSTEM AND FISH CREEK DAM
ENVIRONMENTAL IMPACT STATEMENT
DESIGN
CONSTRUCTION
ULTIMATE DEVELOPMENT
POT HOOK/THREE FORKS DAMS AND BAGGS PIPE LINE
RESOLVE COLO. INTEREST
DESIGN
CONSTRUCTION
0 1 2 3 198- 199-456 7 8 9 0 1 2 345 6 7 8 9
-
---
...... -~
-----~--------
200-0 1 2 3 4 5 6 789 0
-
20'1- 202-1 2 3 4 5 6 7 E 9 o 1 2 3 4 5 6 7 8 9
LITTLE SNAKE RIVER WATER MANAGEMENT PROJECT
PREFERRED DEVELOPMENT PLAN YEARS 1984 THROUGH 2029
FIGURE 5
co o
~ • o -ID
Diversion Dam should be revised. The model has been separately modified by
Western Water Consultants and Boyle Engineering in 1984. These two
modifications plus the proposed exchange of water between the Casper Alcova
Irrigation District and the City of Casper should be incorporated into a
single model.
Since Wyoming
utilization of North
has a
Platte
major
River
interest
waters
in the present and future
and the WWDC is involved in
planning and development of projects such as the LSRWMP which need a
computer model to evaluate .the impacts and benefits of imported water, it
is recommended that the WWDC initiate this effort to insure the model's
reliability as a planning tool.
-17- STONE 8c WEBSTER A
--------------------------------------------------------------------------~ .
Douglas
" ( '-~, "~ s.eetwO
\ ( J KORTES~~~
/ RE& (SEMINOE : l----, RES. J
" • 0,. ~ ~~~ \ 01'1);, C -, ~'\ .&.~. °"PI
,~ont;nental I! ~~ ~
LITTLE SNAKE R:;;~ c.'" tl ~ WATER DEVELOPMENT " Laramie,..,---------- (Q PROJECT \ C. ,.- --- <t IMPORTED WATER '\~ \ 0 .: ffi
----1-_ .• ---....-__ ,,/ £.HEYENJ~EI z
'" I J 0 I /. ~ J I I \ ) COLORADO \ '--.. / .....,.,.--
NORTH PLATTE RIVER BASIN
FIGURE 6
STONE Be WEBSTER A
... o • • -c