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<br />(G. W. Leavesley, oral commun, , 1975), These results will be Integrated Into
<br />both the flow-routing and reservoIr-assessment elements,
<br />
<br />Minimum-flow analY8i8.--A low-flow analysis will be made for the basIn
<br />using the Log-Pearson Type III frequency analysis. Low-flow characteristics
<br />will be computed for 7-, 10-, and 30-day minimum mean flow periods at 2-, 10-,
<br />and 20-year recurrence Intervals, As noted by livingston (1970) and Wahl
<br />(1970), minImum-flow analysis in Colorado and Wyoming Is quite complicated
<br />because of surface-water diversions, topography, geography, and climate. In
<br />the Yampa River basin, diversion of water is quite prevalent, affecting many
<br />dally streamflow records,
<br />
<br />For the minimum-flow analysis, the water-diversion data, described ear-
<br />11 er, will be used with the exist ing surface-water records to reconstruct
<br />estimated natural flows at the various surface-water sites, These data then
<br />will be used In the minimum-flow analysis, D, R, Tuthill, Jr., while a grad-
<br />uate student In civil engineering at the University of Colorado, assisted the
<br />project staff in this assessment-analysis c.omponent, and his findings are pre-
<br />sented in his master's thesis (Tuthill, 1975'),
<br />
<br />Time-af-travel 8tudieB.--One or two tlme-of-travel studies are planned
<br />for the Yampa River mainstemfrom Steamboat Springs to Craig, Colo., and the
<br />Little Snake River malnstem from Slater to Baggs, Wyo. The tlme-of-travel
<br />stud.ies wi 11 be made during the spring high-flow and summer low-flow periods
<br />of 1976. Field measurements wIll be made at these two different discharge
<br />conditions and an' approximate time~of-travel versus discharge relationship
<br />will be developed for the study reach (Bauer, 1968), These studIes wi 11 en-
<br />able a more critical analysis to be made on hydraulic-flow conditions as a
<br />basis for evaluat.ing the waste~assImllative capacity of the upper Yampa River
<br />ma instem.
<br />
<br />The tIme-of~.travel studIes. wi 11 be made by the dye-tracer technique
<br />(W.Ilson,1968). The dye "cloud!' will be ana.lyzed for .longItudinal dispersion
<br />and peak concen't rat:i on decay,
<br />
<br />Ground Water
<br />
<br />The primary use of ground wa.ter in the Yampa River' basin has been for do-
<br />me'st:Lc, livestock" and municipal supp:lles, Wells principally have been drill-
<br />ed in unconfined"a.l,luvial aquJfers that generally follow. stream-cut valleys,
<br />Mast wens a,re' les,s than 100 feet (30, m) deep, but a few. have penetrated deep-
<br />er aquJ fers,
<br />
<br />Resu.l ts of two ongo i ng ground~water reconna.i ssance Investigat Ions by the
<br />U,s.. Geological Survey in cooperation with the Colorado, D:ivisi.on of Water Re-
<br />sources, Office 0.1' the State Engineer, and the U,S, Env+ronmental ProtectIon
<br />Agerrcy will provJde supp,lementaJ information, A few of the InventorIed wells
<br />may be designated: as monitoring, sites for pedodic observations of water lev-
<br />els and, selected: water-quality measurements. .In addition, s,everal deep wells
<br />presently are beIng dri lied' in the northeastern part of the basin in Wyoming
<br />as part of a Htholog.i'cal study by, the Geo,logical Survey, Once comp.leted,
<br />some, of these. welTs w.il1 be maJntained. as obse,rvation well s for water level s,
<br />
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