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River Basin Plans
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Bear River Basin Water Plan
Prepared for the
Executive Summary, Bear River Basin Water Plan
Basin Planning Process
Wyoming is undertaking pro-active statewide basin planning activities to represent changing
conditions since the planning efforts in the late 1960s and early 1970's resulted in the publication
of the Wyoming Framework Water Plan. The Framework Water Plan consisted of summaries of
current water conditions and planning projections for six of the seven major river basins in
Wyoming; the Bear River basin was not included in the Framework Plan. Due to technology
constraints in the early 1970's, the data, mapping, and analyses tools used in developing the
Framework Plan could not be easily updated to reflect changing conditions or new data.
The 1996 legislature directed the Wyoming Water Development Commission (WWDC) and the
State Engineer's Office (SEO) to prepare a recommendation for updating the 1973 Framework
Water Plan. The recommendation concluded that the planning process should accomplish the
following three main objectives:
- Develop basin plans with the participation of local interest groups.
- Provide decision makers with current, defensible data to allow them to manage water
resources for the benefit of all the state's citizens. Provide access to the progress, data, and
results of the basin plans in a variety of formats for use by state agencies and Wyoming
citizens, including access via the Internet.
- Develop basin plans, using contemporary water resources data and tools, that quantify
existing surface and ground water uses and identify potential future uses.
This Bear River Basin Water Plan Report, summarized in this document, is one of the results of
the application of these objectives to the Bear River Basin. The Bear River Basin Water Plan
and supporting documents, data, and models are available from the Wyoming State Water Plan
Web Site (http://waterplan.state.wy.us/), or directly from the WWDC.
The Bear River headwaters are in the Uinta Mountains in Utah. The Bear River enters Wyoming
flowing north through Evanston and into Woodruff Narrows Reservoir. Just downstream of
Woodruff Narrows it flows into Utah and then re-enters Wyoming south of Cokeville. The flow
is increased greatly by the Smith's Fork River before it enters Idaho, flowing west near the town
of Border. As shown in Figure 1, the Bear River then heads north through Idaho, loops back
south, re-enters Utah, and discharges into the Great Salt Lake. The flow in the Bear River is
allocated between Wyoming, Utah, and Idaho based on diversions and storage defined in the
Bear River Compact. Agriculture accounts for the largest water use in the Wyoming portion of
the basin. Surface and ground water are used to irrigate over 60,000 acres of crop land.
Bear River Basin
The Bear River Compact divides the Bear River Basin into three main divisions. Two of these
divisions are partially within Wyoming. The Upper Division includes portions of Wyoming and
Utah that are upstream of Pixley Dam, located in Wyoming south of the town of Cokeville. The
Central Division includes portions of Wyoming and Idaho between Pixley Dam and Stewart
Dam in Idaho. Much of the information provided in this document is organized by these
The Bear River Basin planning effort met the following four major objectives, which are each
summarized in separate subsequent sections:
The Basin Water Use Profile task determined and quantified the current surface and
ground water uses within the basin (Section 3).
The Basin Water Quality Profile task determined the current surface and ground water
quality within the basin (Section 4).
The Available Water Determination task identified surface and ground water available
for future basin water development (Section 5).
The Demand Projections and Future Water Use Opportunities task identified likely
uses, quantities, and opportunities to meet future water demands in the basin. (Section 6)
Basin Water Use Profile
The total basin water consumed in Wyoming due to human influence include the following
- Agriculture. Agricultural use includes both surface water diverted or ground water
pumped for use in irrigating crops, and water used by cattle and sheep. There are 40,400
and 23,500 irrigated acres in the Upper and Central Divisions of Wyoming respectively.
In the Upper Division, approximately 99 percent of the irrigated acreage is meadow
grass. Only about 1 percent is planted in alfalfa. In the Central Division, about 86
percent is meadow grass, with the remaining planted in alfalfa and small grains.
- Municipal and Domestic. Municipal and domestic use includes surface water diverted or
ground water pumped for distribution by the City of Evanston and the Town of
Cokeville. In addition, it includes domestic ground water use by individual households
not connected to public water systems.
- Industrial. Industrial use includes commercial or industrial water use by entities not
connected to public water systems.
- Environmental. Environmental use includes water used to create and maintain wetlands
and wildlife habitat, water used to maintain minimum fishery pools in reservoirs, and
water designated to maintain minimum flows for fisheries in streams.
- Recreational. Recreational use includes water used to maintain minimum recreation
pools in reservoirs and water designated to maintain minimum flows in streams for
boating or aesthetic purposes.
- Reservoir Evaporation. Reservoir evaporation is a water "loss" that would not occur in
the absence of reservoirs, therefore is considered a consumptive use of water due to the
influence of humans.
The current total basin consumptive use in Wyoming is approximately 102,000 acre-feet per
year. Figure 1 shows the total basin consumptive use by type. It should be noted that although
water is diverted to Cokeville Meadows National Wildlife Refuge (environmental use), it is used
to irrigate crops historically grown in the area. Therefore, that consumptive use is included in
the agricultural category. Water is used for recreational purposes in the basin both to maintain
minimum reservoir pools and to maintain minimum streamflows. However, this use is non-
Figure 2 shows the average annual basin consumptive use by supply source.
Basin Water Quality Profile
Total Dissolved Solids (TDS) is a measure of the total amount of dissolved salts in water.
Although TDS does not provide the entire picture on water quality, it is easily measured and is,
therefore, frequently used as an indicator of overall water quality. The following summarizes the
surface water quality analysis for the Bear River Basin:
- The primary use of water in this basin is for agricultural purposes, and when the data
available for Total Dissolved Solids (TDS) and other parameters are compared to
standards set for agricultural use, concentrations are consistently below the water quality
- With the exception of Twin Creek, all the gages have TDS concentrations consistently
below the TDS standards set for drinking water limits.
- Concentrations of TDS vary with flow. During low flow seasons, such as late summer
months and non-irrigation seasons, the concentration of TDS increases, likely because a
larger percent of the flow is agricultural and municipal return flows. During high flow
seasons, such as late spring and early summer months, TDS concentrations decrease.
- Throughout the study period for the USGS water quality gages, no significant increase
has been seen in TDS concentrations.
Unlike continuous surface water quality gages, ground water quality measurements in the Bear
River Basin have generally not been taken at the same location over time. Therefore, it is
difficult to make assessments regarding trends in ground water quality. However, general
conclusions can be made regarding the ground water quality of the aquifer that is tributary to the
Bear River as follows:
- Ground water quality is generally good, but may exceed domestic standards in the area of
the basin around Twin Creek
- Ground water quality usually meets agricultural and livestock standards
- Ground water quality is generally better in the southern (upstream) portion of the basin
Available Water Determination
Surface water availability varies with hydrology and location in the basin. Spreadsheet Models
were developed to represent historic dry, normal, and wet year hydrology in the basin. Current
water use and Bear River Compact limitations were superimposed on the hydrology to estimate
surface water availability in the basin. Figure 3 shows the total available monthly flow in the
Upper Division for dry, normal, and wet hydrologic years.
The following summarizes the Upper Division available flows:
- During a dry year, water for diversion and future permanent use in the Upper Division is
available only during the non-irrigation season. This total amount is approximately
27,000 acre-feet per year.
- Approximately 142,000 acre-feet per year of water is available during normal hydrologic
conditions. About 60 percent of this flow is available during the high runoff months of
May and June.
- Approximately 325,000 acre-feet per year of water is available during a wet hydrologic
year, with over 60 percent of the flow available during May and June.
- For all three hydrologic conditions, the available flows during the non-irrigation season
are limited to the Bear River mainstem between the confluence with Sulphur Creek and
Pixley Dam (includes portions of Utah).
- For all three hydrologic conditions, the available flows during the irrigation season are
limited to the Bear River mainstem between Evanston and Woodruff Narrows Reservoir.
Figure 4 shows the total available monthly flow in the Central Division for dry, normal, and wet
The following summarizes the Central Division available flows:
- During a dry year, there is no additional water available for development in the Central
- Approximately 190,000 acre-feet per year of water is available during normal hydrologic
conditions. This water is only available from March through July, with the majority
available during the high run-off months of May and June. Much of this flow originates
from "spills" over Pixley Dam, and may not be available if future Upper Division
allocations under the compact are completely consumed.
- Approximately 500,000 acre-feet per year of water is available during a wet hydrologic
year, with over 60 percent of the flow available during May and June. Again, much of
this flow originates from "spills" over Pixley Dam, and may not be available if future
Upper Division allocations under the compact are completely consumed.
- For normal and wet hydrologic conditions, there is available flow during the non-
irrigation season on both Smith's Fork and the Bear River mainstem.
Current ground water withdrawal estimates indicate that, on average, less than 3,000 acre-feet
per year of ground water is currently used in the Bear River Basin. The majority of this use is
from the Alluvial Aquifer, defined as the aquifer within the Bear River alluvium. Future
development of this aquifer could provide additional water to meet increased demands, however
there are limitations and restrictions to additional depletions outlined in the Bear River Compact.
These restrictions consider withdrawals from the Alluvial Aquifer to be similar to river
It is estimated that additional development of up to 14,000 acre-feet per year in the Bedrock
Aquifers, defined as aquifers outside the Bear River alluvium, would be sustainable. Well
development in the Bedrock Aquifers needs to be studied in greater detail to determine the
impact on Bear River flows and the extent to which compact restrictions may apply.
Demand projections were developed for two scenarios using an economic based approach. The
planning horizon was 30 years, therefore growth was estimated through the year 2030. The High
Case Scenario incorporates the most growth in key economic sectors that is reasonably likely to
occur over the forecast horizon. This scenario incorporates the aggressive assumption that each
of the key sectors will achieve its highest likely growth at the same time, providing an upper
bound for water planning purposes. The Low Case Scenario incorporates the lowest growth
reasonably likely to occur in key economic sectors. This provides the lower bound for planning
High Case Scenario
Total basin water diversion requirements are projected to increase by about seven percent from
year 2000 to year 2030 under the High Case Scenario. Under normal hydrologic conditions, this
amounts to about 21,400 acre-feet; under dry hydrologic year conditions the increase would be
about 29,000 acre-feet. The following summarizes uses for the High Case Scenario:
- Total agricultural water demand grows slightly over the planning period, whether
measured in terms of diversions or consumptive use. Despite a lack of growth in the
sector, agriculture continues to comprise the vast majority of total water demand under
the High Case Scenario; agriculture is responsible for 97 percent of total water diverted
and 94 percent of total consumptive use in the year 2030.
- Municipal water demand almost doubles over the 30-year planning period, however, it
remains a relatively small sector, accounting for only 2.6 percent of total water
diversions, and 4.8 percent of total consumptive use within the Basin.
- Water demand is projected to more than double in all municipal sectors in Evanston,
however, water demand in Cokeville remains almost constant over the planning period.
This is because the projected population growth of Cokeville is offset by the assumption
that per capita water demand will decline sharply due to the implementation of usage
based water rates in the town during the planning period.
- Rural domestic water demand is projected to almost double over the next 30 years, due in
large part to the projected population growth around the Evanston area.
- Water demand within the industrial sector is not projected to change substantially over
the projection period.
- Changes in overall water demand over the 30-year planning period are relatively small
because of the continued domination of the agricultural sector.
Low Case Scenario
Total water diversion requirements under the low economic forecasting scenario are projected to
be slightly lower in 2030 than they were in 2000. The following summarizes uses for the Low
- Total water demand in the agricultural sector declines over the projection period by about
6 percent. The decline in livestock water demand directly reflects the impacts of a
change in BLM grazing policy and the implementation of the Cokeville Meadows
- The environmental sector line item included in the low scenario specifically refers to the
wetland water requirements within the Cokeville Meadows Wildlife Refuge. If the
refuge is fully implemented, water impoundments will likely be made in order to
augment existing waterfowl habitat area.
- In the municipal sector, the modest decline in both diversions and consumptive use is the
direct result of two factors: constant population levels and the anticipated implementation
of a usage based water rates system in Cokeville.
- The most significant change under the low scenario was the complete elimination of any
industrial water demand within the Basin. This result is reflective of the assumed
extraction of all remaining recoverable natural gas reserves within the Basin during the
30-year projection period.
- Changes in overall water demand over the 30-year time horizon are relatively small
because of the continued domination of the agricultural sector.
Bear River Basin-Wyoming
Current and Projected Annual Water Diversion Demand
||2030 Low Scenario
||2030 High Scenario
||Normal Demand Year
||High Demand Year
||Normal Demand Year
||High Demand Year
||Normal Demand Year
||High Demand Year|
Future Water Use Opportunities
Economic Development Opportunities
Wyoming's approach to basin planning includes the identification and prioritization of future
water use opportunities. This process involved extensive interviews with representatives from
government, larger industrial entities, agriculture, energy, and tourism. These interviews and
investigations did not result in the identification of any specific economic plans or opportunities
beyond the growth scenarios presented herein. No listing of future opportunities, therefore, is
included as part of this Bear River Basin Plan. As opportunity(s) are identified in the future, the
spreadsheet modeling software created as part of the planning effort will we a valuable tool in
ascertaining the feasibility and/or impacts of individual projects.
The state of Wyoming is supportive of water conservation as an environmentally responsible
policy. In many cases, water conservation offers a direct economic benefit to water users. In the
case of municipalities, for example, reduced water consumption translates into reduced treatment
and operational costs. In the case of irrigation, one would expect agricultural users to benefit
through increased overall water availability due to conservation measures. However, in the Bear
River Basin, this is not necessarily the case. Current land application practices in the Upper
Division almost exclusively involve flood irrigation. As a result of this practice, the Bear River
is recharged, with up to 50% of the return flows re-entering the streams later in the irrigation
season when divertible flows would normally be much less. This in-ground storage actually
benefits water users late in the irrigation season. Irrigation conservation may be more
economically attractive in the Central Division where Water Emergency conditions typically
occur earlier in the season.
Projected future water supply demands will require supplemental water from storage or from
ground water, since there is essentially no available water for diversion during dry years.
There were essentially 8 dry years in the 28 year historical study period. This represents
approximately 3 out of every 10 years in which there are no additional divertible flows in excess
of current water rights. There are virtually no available flows in either division during dry year
periods, in any months. To guarantee a firm yield beyond existing allocations during these dry
year periods, additional storage reservoirs would be required.
Based on the normal year hydrology, the best development plan would be the construction of
storage up to the yield available during these years - 150,000 and 190,000 acre-feet in either the
Upper or Central Divisions respectively. There would be the need to carry over some storage to
guard against dry year yields (zero) and to take into account losses from the reservoir(s). The
firm yield, therefore, would be on the order of 75,000 acre-feet in the Upper Division and 95,000
acre-feet in the Central Division. The State of Wyoming has a remaining allocation of
approximately 4318 acre-feet of compact storage rights under the original 1958 Bear River
Compact. Additional storage development in excess of 4318 acre-feet would be subordinate to
the requirement that storage cannot take place in the Upper or Central Division when the water
surface elevation of Bear Lake drops below 5911 feet.
There have been several previous studies directed toward the feasibility and capacity of various
reservoir sites within the Bear River Basin. The potential for future reservoir construction was
presented to the Basin Advisory Group (BAG) on several occasions for discussion. The
consensus of the BAG was to not pursue or list storage as an option at this time. This feeling
was, in part, due to economic concerns (cost vs. benefit) and environmental permitting concerns.
None-the-less, storage is a viable option in the future as the need and/or economic desirability of
Near the completion of the planning study, water users from the Cokeville area approached the
Wyoming Water Development Commission to initiate discussions relative to developing storage
on the Smith's Fork. The Smith's Fork appears to have excellent storage potential from a
hydrologic standpoint. There is a permit pending for the Ferney Glade Reservoir site on the
Smith's Fork, which was filed in 1960 for 5201 acre-feet. A larger reservoir would likely
require the partnership and participation of downstream states.
Continued Planning Process
Wyoming's Water Planning Process is not intended to provide a directive for the implementation
of future water development, but rather to provide the basic information needed to address water
issues that arise in the future. One of the most important products of the planning process is the
collection, storage in a useable format, and understanding of basic water resource and water use
data in the Bear River Basin.
The Bear River Basin planning effort has created an informed group of citizens interested in
water issues. The members of the basin advisory group have chosen to continue to meet three
times a year to discuss water issues. The Bear River Basin Water Plan Report will provide the
framework for discussions and planning efforts related to current water use, projected water use,
compact issues, and other regulatory issues in the Basin.
Previous Wyoming water planning documents provided useful snapshots in time, but were often
outdated within a few years. The advance of computer and Internet technology will help assure
that the Statewide Water Planning Process will remain current and accessible to the citizens of
Wyoming. The WWDC intends to update each basin water plan approximately every five years.