Bear River/Bear Lake - Hydrologically, Where Would They Be Without Being Connected?

              UTAH STATE UNIVERSITY
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Bear River/Bear Lake - Hydrologically, Where Would They Be
Without Being Connected?
by
Norman E. Stauffer Jr., Ph.D., P.E., and Craig W. Miller, P.E.
Bear River/Bear Lake Model
A simplified model of the Bear River and Bear Lake was created to show the effects
of not connecting the Bear River with Bear Lake. A map of the Bear River Basin showing the
Bear River and Bear Lake is shown on Figure 1. A schematic of the simulation model is
shown on Figure 2. The model operates on a monthly time step for the 70 year, 1923-1992
period. Reach gains were determined from historical flow data, at Alexander, Oneida, and
Cutler Dam. The Flows at Cutler Dam were obtained by adding the Bear River Canal
Company East and West Side canals to the Bear River at Collinston immediately below the
dam. Monthly precipitation and evaporation estimates were made for Bear Lake. The model
was then operated assuming that water from the Bear River would not be diverted into Bear
Lake.
If Bear River flows were not stored in Bear Lake, historical irrigation diversions and
return flows would have been affected from Bear Lake to the Great Salt Lake. The detail
required to model this in depth is beyond the scope of this study. An approximation was used
to back out the historical Bear Lake storage releases for irrigation. This was accomplished by
distributing in percentages the flow changes from historical values during the irrigation season
to the simulated land areas shown on Figure 2. These percentages are shown in Table 1. The
return flows from the flow changes, positive and negative, were returned to the river with a
50 percent assumed depletion. Return flows to the river were lagged, 50 percent in the month
of diversion, 30 percent one month later and 20 percent two months later.
Table 1. Assumed Distribution of Flow Differences from Bear Lake during the
Irrigation Season to the Simulated Land Areas.
Land Area Percent of Flow Difference From Bear
Lake Diverted to Land Areas
Bear River at Alexander to Oneida. 10%
Bear River at Oneida to Collinston 25%
Bear River at Cutler Dam - 65%