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<br />
<br />Comparison of Historic Randlett Flows to USFWS
<br />Recommended Flows
<br />
<br />A comparison of the USFWS flow recommendations with historical flows at Randlett was
<br />made to determine flow deficiencies that would have occurred over the period of record
<br />(1912-1994),
<br />
<br />Analysis of the flow volume required to meet USFWS flow recommendations under a dry
<br />year scenario for the period of record was accomplished by looking at the yearly
<br />deficiencies in dry years. The flow volume needed does not necessarily equal the
<br />cumulative difference for the entire year as shown in the table below. Most of the yearly
<br />totals are influenced by the summer months of July, August, and September having higher
<br />flows than the USFWS recommendations. These reduce the total yearly deficiency.
<br />However, the critical amount required is the total monthly deficiencies during the period
<br />from October through May. This is the amount that would be needed in storage, or result
<br />from reduced flows going into storage.
<br />
<br />There are several years during the extended period of record from 1912-1994 when the
<br />USFWS dry year flow requirements were not met and would have required additional
<br />water in the Duchesne River during some periods of these years. These years include the
<br />early 1930s, 1959-1961, 1977-1980, and the period from 1989-1994. The most critical period
<br />has been the recent drought years from 1989-1994. For this reason, this period was used to
<br />determine the potential maximum amount of water that would be needed to meet the
<br />USFWS dry year flow requirements in anyone year. For the period from 1989 to 1994, the
<br />flow needed monthly and annually to meet the USFWS flow recommendations is shown
<br />below . Values in parentheses represent differences between recommended and existing
<br />flows in the Duchesne River.
<br />
<br />
<br /> Oct Jan Feb A r Ma Jun u\ Au Se t Total
<br />1989 (850) (8,098) (14,729) (13,875) (13,316) (5,377) (363) (15,464) (30,730) 807 2,254 2.017 (97,725)
<br />1990 (3,438) (13.207) (19,048) (18,513) (18,089) (16,174) (9,328) (17,477) (18,995) . 2,490 790 2,221 (128,767)
<br />199\ (636) (10,678) (15,108) (14,680) (13,032) (15.159) (8,769) (17,364) (16,149) 3,109 4.766 5,763 (97,937)
<br />1992 234 (8,874) (14,537) (11,035) (IO,OS6) (11.258) (8,648) (14,905) (32,277) 3,595 1,913 1,680 (104,168)
<br />1993 (2,356) (11,178) (15,246) (15,140) (14,743) (9.212) (3,879) 21,467 (1,180) 3,OS4 3,991 2.497 (41,925)
<br />1994 5,785 1,077 (2,906) (8,596) (8,404) (10,903) (7,194) (16,126) (33,310) 412 90 159 (79,918)
<br />
<br />The average annual flow deficiency during the period from 1989-1994 is over 91,000 acre-
<br />feet per year, with a peak year in 1990 of approxiInately 129,000 acrc..feet. J.A..S can be seen
<br />from the above table, the flow deficiencies primarily occur in the period from November
<br />through June. For the November through June period during 1989-1994, the flow deficiency
<br />is over 103,000 acre-feet with a peak of 134,000 acre-feet in 1990. Of the flow deficiency
<br />during 1989-1994, an average of approximately 60,000 acre-feet occurs in the winter months
<br />from November to April. With these deficiencies occurring in the winter months, potential
<br />
<br />SLCI 1341 07\REPT1,DOC
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<br />E.5
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