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<br />when the flow regime changed from historical flow regime, because the change was
<br />incremental. Major changes occurred with the CUP project coming online in 1970. Thus,
<br />the pre-project and post-project periods are assumed to be pre- and post- 1970, respectively.
<br />To assist in determining pre-project flows and the effects of longer term record, the My ton
<br />gauge was used to extend the flow record of the Randlett gauge to earlier periods with less
<br />development.
<br />
<br />Extending the flow record for the Randlett gauge was accomplished by making a linear
<br />correlation with the Duchesne River at My ton stream gauge. The extended record shows
<br />(approximately) a 20 percent increase in pre-project average flows with an average volume
<br />of 533,700 acre-feet. Flow statistics for the various periods are summarized in the table
<br />below.
<br />
<br />Duschense River at Randlett
<br />
<br />
<br />Period Oct Nov
<br />1912-1994 22,739 24,932
<br />1912-1969 23,341 26,093
<br />1970-1994 21,342 22,238
<br />
<br />., .",,~~.""_M1 . ~_' .~ '."'.)""''''''_~
<br />~'lgR~'GI1, _eJ!;JLI\fl!Y:fF,:I!'~W$(~BrFim:P,,,. . " .. "".{!c."' ,,;:~;lJj~1f!..~;~
<br />i2t;;{~",~ tt~~,~.u;e(m&M"Md#" . ~ ,_ i'B{ , &;:.\Il:ii!!f.;4'."","^~""",~
<br />Dee Jan Feb Mar Apr May Jun Jul Aug Sep Annual
<br />26,516 25,401 25,589 32,242 30,805 87,878 134,476 35,295 16,177 16,882 478,932
<br />28,187 26,910 27,027 33,813 35,873 106,638 1S1,033 38,517 17,891 18,410 S33,732
<br />22,642 21,901 22,253 28,598 19,048 44,3S5 96,064 27,820 12,201 13,336 351,796
<br />
<br />
<br />Period Oct Nov Dee Jan Feb Mar Apr May Jun Jul Aug . Sep
<br />1912-1994 370 419 431 413 457 524 518 1,430 2,260 574 263 284
<br />1912-1969 380 439 459 438 483 550 603 1,735 2,539 627 291 309
<br />1970-1994 347 374 368 356 397 465 320 722 1,615 453 198 224
<br />
<br />Review of USBR Pre-Development Flows
<br />
<br />An analysis of the Duchesne River has been performed by the United States Bureau of
<br />Reclamation (USBR) to determine "Pre-Development Flows" of the Colorado River Basin.
<br />These flows were developed by the USBR for the whole Colorado River Basin in an attempt
<br />to develop virgin river flows. These were developed primarily to be used in compact issues
<br />on the Colorado River among the states. They historically have been updated every. 5 years.
<br />The average yearly flow for the period of record from 1912-1990 is 768,000 acre-feet. This
<br />compares to an average yearly flow of 498,000 acre-feet for the same period of record at the
<br />Randlett gauge, or a long-term difference of 270,000 acre-feet per year. This value would
<br />represent theoretical depletions from the Duchesne River system from all human usage,
<br />
<br />The average yearly flow difference between the USBR flows and the Randlett gauge are
<br />shown below for various periods of record.
<br />
<br />k;TI"''''''{''''::'.l';':'1f,--ry-Mil'" ~'l''0:1filf[cl?t''}j':i'J.?r;~',',''1-,0'' '--,~'~,~' "m--''''-~>'Y''
<br />1ii1~~:R~noaiilwl,~USBR}j:illl'Tlig~'FIPW'!ilI tRand
<br />r,-,:'iI,t""4,,~q"'fi!'1l;::~'~',g,, ':"i:\._~""'-*'_'t',0,%?J.',0'_0/" ;"~i';~""~,1!".'~ , " ",'"'f"!!P
<br />1912-1990 768,023 497,963
<br />1912-1970 787,836 528,033
<br />1970-1990 741,621 399,170
<br />
<br />
<br />270,040
<br />259,803
<br />342,451
<br />
<br />SLC\134107\REPT1.00C
<br />
<br />E-2
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