WATER
QUALITY
EVALUATION
SAVERY-POT HOOK PROJECT
COLORADO.WYOMING
ENVIRONMENTAL PROTECTION AGENCY
REGION
DENVER. COLORADO
JUNE 1971
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WATER QUALITY EVALUATION
OF THE
SAVERY-POT HOOK PROJECT
COLORADO, WYOMING
An evaluation of the Bureau of Reclamation's pro-
posed Savery-Pot Hook Project reveals that with
adequate treatment municipal and other minor waste
loadings will not significantly affect water quality
for present and projected water uses in the Project
area. Therefore, no storage in Savery and Pot Hook
Reservoirs is needed to provide flow regulation for
maintaining satisfactory organic water quality in
the Colorado River. The use of Project water for
irrigation purposes will result in a 2.5 mg/1 in-
crease annually in the total dissolved solids con-
centration of the Colorado River at Lake Mead. The
economic impact of this salinity increase upon water
users below Lake Mead is estimated to be $165,600
annually, based on 1970 economic conditions. This
appraisal provides an estimate of the effect of
salinity increases resulting from the Project and
will be useful in evaluating and justifying control
measures for water quality improvement. Control
measures are recommended for incorporation into the
construction and development of the Project to mini-
mize the adverse effects of salinity.
Environmental Protection Agency
Region VIII
Denver, Colorado
June 1971
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TABLE OF CONTENTS
Page
Introduction 1
Water Quality in the Project Area 2
Project Impact on Water Quality 4
Storage for Streamflow Regulation 6
Waste Source Control 7
Conclusions 10
Recommendations 10
References Cited 12
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SUPPLEMENTAL WATER QUALITY
EVALUATION REPORT
on the
SAVERY-POT HOOK PROJECT
June 1971
Introduction
This report on the Definite Plan of the Bureau of Reclamation's
(USBR) Savery-Pot Hook Project supplements the Public Health Service
report entitled, "Public Health Aspects of the Savery-Pot Hook Project,"
dated December 1957 and revised in April 1960. The previous report
pertained to the USBR feasibility studies for this Project.
A supplemental report was considered necessary because the
following events have occurred since April 1960:
(1) The enactment of the Water Pollution Control Act, as amended
(33 U.S.C. 466 et seq.) and issuance of Executive Order 11507,
dated February 5, 1970; transfer of the Federal Water
Quality Administration (FWQA) to the Department of the
Interior; and subsequent transfer of the Federal Water Quality
Administration to the Environmental Protection Agency
on December 2, 1970;
(2) The USBR requested an updated water quality report;
(3) Changes have been made by the USBR in the proposed
Project plan; and
(4) The Environmental Protection Agency has completed a study
of the economic impact of salinity in Colorado River water.
The Savery-Pot Hook Project will provide water for irrigation,
recreational, and fishery purposes. Principal Project features in-
clude two reservoirs; Savery Reservoir on Savery Creek in Wyoming
and Pot-Hook Reservoir on Slater Creek in Colorado. Both creeks
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are tributaries of the Little Snake River, an interstate stream.
The Project reservoirs will supply 66/000 acre-feet of irrigation
water for full service to 17,920 acres and supplemental service to
14,330 acres, in both Colorado and Wyoming.
Water Quality in the Project Area
A limited water quality survey was conducted by FWQA in
July 1970 along the Little Snake River from Slater, Colorado to
Baggs, Wyoming to check reported low dissolved oxygen concentrations
and high pH values. The survey revealed dissolved oxygen concen-
trations ranging between 6.5 mg/1 and 7.7 mg/1 and pH values ranging
between 7.5 and 8.0. The discharge ranged between 37 cubic feet per
second and 42 cubic feet per second. It can be observed from the
tabulation shown below that the values for these parameters meet the
water quality standards criteria of the States of Colorado and
Wyoming for this reach of the Little Snake River. Water quality
standards criteria for other parameters are also being met in the
Project area.
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Water Quality Standards for the Little Snake River
Standards of Quality I/
Designated Water Bacteria Dissolved Dissolved
Use for the (Count/ Oxygen Temp. Solids
Little Snake River2/ 100 ml) (mg/1) oF pH (mg/1)
State of Colorado
Public Water Supply < 1,000* >4 6.0-9.0 500
Cold Water Fishery <1,000 >6 < 70 6.5-8.5
State of Wyoming
No use designated <2,000** >6 <78 6.5-8.5
Basic standards
apply
I/ Adapted from State Water Quality Standards documents; refer to state
standards for specific language and additional criteria.
2/ Little Snake River - from the source to intersection with county roads
east of Powder Wash, Colorado (About 3 miles south of the Wyoming-
Colorado stateline).
*Fecal coliforms (log mean value).
**Fecal coliforms (mean value).
The minimum flow through the Baggs-Dixon area required to assimilate
domestic wastes and maintain a minimum dissolved oxygen content of 6.0
mg/1 is 1.0 cubic feet per second (cfs). The assumptions used in cal-
culating the minimum flow requirements are as follows:
1. The Dixon and Baggs, Wyoming populations in 2010 will be
200 and 400, respectively.
2. Each population equivalent contributes 0.17 pounds of five-
day 20°C biochemical oxygen demand (BOD5).
3. Waste treatment facilities in the Project area will remove 85
percent of the BODg contributed by the entire population.
There are no industrial wastes in the area. Examination of the U.S.
Geological Survey flow records for a 37-year period at a station near
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Dixon indicates that the streamflow is greater than 1 cfs over 95 per-
cent of the time. Generally, the low-flow periods occur during August
and September.
The Project will cause a change in the low-flow pattern. Presently
the irrigators divert most of the seasonal irrigation supply during the
spring runoff period because storage is not available. During the latter
part of the irrigation season the irrigators divert most of the available
streamflow. After the Project is built/ a fairly constant supply of
water will be available throughout the growing season. Because of the
complex pattern of water rights, diversions, and return flows in the
Baggs-Dixon area, it is difficult to determine the precise flow of the
Little Snake River in that area during the irrigation season. However,
since high priority water rights downstream from Dixon will be met after
the Project is built, it is anticipated that the minimum flows during
August and September will exceed those occurring before the Project is
built. Therefore, these flows will be more than adequate to meet the
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minimum flow required to assimilate domestic wastes. A discussion of
the mineral quality of water in the Project area is included in the
following sections.
Project Impact on Water Quality
The major impact of the proposed Project on water quality will re-
sult from increases in salinity (total dissolved solids) concentrations
of the Colorado River. A comparison of the average annual pre-project
and post-project flows and total dissolved solids (TDS) concentrations
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at three locations downstream from the Project area is shown in the
tabulation below.
Pre-Project
River Location
Flow
(A.F.)
TDS
Cone.
(mg/1)
Post-Project
Flow
(A.F.)
TDS
Cone.
(mg/1)
Change
in TDS
Cone.
(mg/1)
Little Near Lily, 451,000 196 424,400 224 + 28
Snake Colorado
Green Ouray, 4,505,500 382 4,478,900 386 + 4
Utah
Colorado Lake Mead 10,288,500 729.5 10,261,900 732 +2.5
Post-project TDS concentrations are based on an annual Project depletion
of 26,600 acre-feet from the Little Snake River and its tributaries and
an estimated annual Project salt load contribution of 8,960 tons from
irrigation water use. This amounts to 0.5 tons of salt per acre from
the new lands. The annual increase in TDS concentrations of 28 mg/1
and 4 mg/1 near Lily, Colorado and Ouray, Utah, respectively, will have
no significant economic impact within and between the Project area and
Lake Mead because: (1) the quantity of water used in these reaches
is small, and (2) the magnitude of the salinity increase in the range
of mineral quality existing in these reaches of the rivers will have
very little effect on beneficial uses.
The estimated 2.5 mg/1 increase in the TDS concentration at Lake
Mead resulting from use of Project water will have a detrimental effect
on all Colorado River waterusers below that point. Data developed by
FWQA's Colorado River Basin Water Quality Control Project indicate
that a 2.5 mg/1 annual increase in the TDS concentration at Lake Mead
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will result in an average annual direct equivalent penalty cost— of
about $109,000 and an average annual indirect equivalent penalty cost
of about $56,600. These figures are based on a 100-year period of
analysis, beginning in 1970, at 3-1/8 percent interest rate and include
the direct and indirect effects upon agricultural, municipal, and
industrial water users below Hoover Dam.
Storage for Streamflow Regulation
Mineral water quality will be degraded as a consequence of irri-
gation on the Savery-Pot Hook Project. This degradation will have no
significant economic impact in the Project area or between the Project
area and Lake Mead. Therefore, no flow regulation for mineral quality
control to protect water uses above Lake Mead is necessary.
Below Lake Mead, mineral quality deterioration will cause down-
stream water users to suffer an annual economic loss estimated at
$165,600, which clearly indicates the need to incorporate all possible
water quality controls in the Project area or any other area in the
Colorado River Basin. The large volumes of water stored in both Lakes
Powell and Mead result in the releases from Lake Mead being fairly
I/ A penalty cost is defined as the difference between the detriments
associated with the use of two different levels of water quality;
thus, it is based on similar economic conditions which permits the
cost effect of water quality to be isolated. Detriments are user
costs incurred when a specific quality of water is used.
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uniform in mineral quality regardless of any seasonal or annual fluc-
tuations in flow and quality of the Colorado River and its tributaries
above the reservoirs. Therefore, any regulation of flow achieved by
storage of presently available water in the Project's two reservoirs
(Savery and Pot-Hook) would not change the quality of water discharged
from Hoover Dam.
In lieu of providing storage in the Project reservoirs for mineral
quality control, salinity control features should be included as part
of the proposed project to mitigate the expected adverse effect of the
project on mineral quality. These salinity control features should
be installed and operated in the Project area or any other area in
the Colorado River Basin where they are found to be effective and
efficient.
Present and projected municipal, industrial and rural organic
waste loads within and below the Project area can be controlled with
adequate treatment at the source. Therefore, inclusion of separable
storage in Project reservoirs for regulation of streamflow for the pur-
pose of water quality control is not needed.
Waste Source Control
Potential salinity control measures may be divided into two
categories: water-phase and salt-phase. The former comprises possi-
bilities for improving water quality by augmenting the water supply,
while the latter includes prospects for improving water quality by
reducing the salt input.
Several water-phase control measures described below appear to
have some technical merit and should be incorporated in the Project.
CD Phreatophyte eradication on Project lands and along canals
and drains could prevent loss of water and make more water
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available for dilution. It should be recognized, however,
that phreatophyte eradication may result in loss of wild-
life habitat and winter protection for cattle and sheep.
(2) Better control of the quality of water applied through
conservation irrigation; the use of irrigation and crop-
ping methods that best fit a particular soil, slope, crop and
water supply also offer possibilities for controlling
mineral quality.
(3) Installing closed conveyance systems or lining canals and
major laterals can result in higher delivery efficiencies
and consequently improved water quality. The reduction in
water loss would prevent unnecessary leaching of salts from
non-project soils. Proper land preparation by grading and
leveling also conserves water.
Potential salt-phase control measures include the careful
selection of land to be irrigated and the provision of better land
drainage. Because of the high water table in the Project area, improved
land drainage is especially needed. Those lands naturally high in
alkaline or sodic salts should be eliminated from consideration in
favor of soils having low natural salt content. The leaching of
irrigated lands can be assisted by installing subsurface drainage
systems for lands to be newly irrigated on terraces or mesas and
alluvial fans above the river flood plains. Also protective or cut-
off drains could be provided at the base of the escarpments to prevent
return flows from these higher lands from encroaching on lower flood
plain lands. With installation of such a drainage system, the salt
load over a number of years may be reduced. Other measures could in-
clude sealing of saline wells and springs, interception and transport
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of highly saline waters to impervious evaporation ponds, and desalting.
Some of these measures are included in the project plan. Lands naturally
high in alkaline or sodic salts were eliminated from consideration during
normal land classification procedures. The project plan provides for
the inclusion of drains and the lining of canals and major laterals.
In order to minimize water quality problems associated with
Project construction activities, the Project contract documents should
contain clauses making it the responsibility of the contractor to comply
with all applicable Federal, state, county and local laws concerning
pollution of rivers and streams. This would require the contractor to
give careful attention to pollution problems such as disposal of sani-
tary wastes and production of sediment during construction.
It is anticipated that both Project Reservoirs will provide diversi-
fied recreational opportunities, such as picnicking, camping, fishing
and boating. Recreational uses expected at the reservoirs are potential
sources of pollution that, if not properly controlled, could create local
water quality problems both in the reservoir and in downstream reaches
of the Little Snake River. Sanitary waste disposal systems with no
surface effluent discharges will be required at all recreation areas.
In addition, facilities to 'receive and treat the contents of boat waste
holding tanks and containers should be provided at appropriate locations.
Provisions should also be made to require that fuel dispensing equipment
on docks be provided with safety features that will prevent the acci-
dental discharge of petroleum products to the reservoirs. The essential
features of waste disposal facilities for recreational areas should be
submitted to the Environmental Protection Agency during the early stages
of planning.
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Conclusions
1. Releases and bypasses from Project reservoirs to serve project and
non-project lands below the Baggs-Dixon area in addition to natural
flows of the Little Snake River will be adequate to assimilate
tributary wastes after adequate treatment. Therefore, inclusion
of separable storage in the Project reservoirs for regulation of
stream flow for the purpose of water quality control is not needed.
2. Irrigation by Project developed water will increase the salinity
(total dissolved solids) concentration in the Colorado River at
Lake Mead by 2.5 mg/1. This increase in salinity will result in
an estimated average annual total equivalent penalty cost of
$165,600.
3. Regulation of flow achieved by storage of presently available water
in Savery and Pot-Hook Reservoirs would not change the mineral
quality of water discharged from Hoover Dam.
4. Project construction activities and wastes generated by recreational
activities may cause water quality degradation in the Project
reservoirs and the Little Snake River unless adequate water pollution
control measures are provided.
Recommendations
To mitigate the potential losses to downstream water users resulting
from the proposed Project, it is recommended that:
1. The proposed Project be operated in coordination with all other
Federally-funded water resources projects in the Colorado River
Basin to meet State-Federal water quality standards.
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2. Additional salinity control features be included as a part of the
proposed project to mitigate the expected adverse effects of the
project on water quality. Some salinity control features are in-
cluded in the project plan. Other measures that should be con-
sidered are the sealing of saline wells and springs, interception
and transport of highly saline waters to impervious evaporation
ponds, desalting, and phreatophyte control. The Project Definite
Plan should provide for installation and operation of salinity
control measures in the Project area or any other area in the
Colorado River Basin where they are found to be effective and
efficient.
3. Provisions be included in Project construction specifications to
assure that appropriate steps are taken by the contractor during
Project construction to protect the quality of the Little Snake
River; and
4. The wastes associated with recreational activities at the proposed
Savery and Pot-Hook Reservoirs be adequately treated in systems
that will not discharge treated effluent to the reservoirs.
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References Cited
1. U.S. Department of the Interior, "Quality of Water,
Colorado River Basin," Progress Report No. 4,
January, 1969.
2. W. V. lorns, C. H. Hembree, and G. L. Oakland, "Water
Resources of the Upper Colorado River Basin - Technical
Report," Geological Survey Professional Paper 441, 1965.
3. W. V. lorns, C. H. Hembree, D. A. Phoenix, and G. L.
Oakland, "Water Resources of the Upper Colorado River
Basin-Basic Data," Geological Survey Professional
Paper 442, 1964.
GPO 836-687
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