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j C04POQ,1ilOM <br />~' S.0 ~ COyCLUSI0N5 AVD RECO`n!E:ID?.TIO\S <br />During the period 28-31 August 1978, a section of the <br />Yampa River near Craig, Colorado caas losing 10 to 17 cubic feet <br />per second or four to eight percent of the upstream flow to <br />ground-water recharge. The loss section was an 800 foot stretch <br />beginning 1.0 miles upstream of the confluence of the Yampa River <br />and [Williams Fork. Losses across the entire 4.6 mile reach from <br />,~ S.H. 13 to the confluence with Williams Fork were 10 to 11 cfs, <br />~ or four to five percent of the flow at S.H. 13. This included <br />an estimated evapotranspirative loss of about two cfs, yielding . <br />~ net losses of eight to nine cfs. Whereas the net losses were <br />less than the probable recharge losses, it is possible that two <br />~ to eight cfs were being discharged from ground caater to the river. <br />~ It was determined that, if present, this discharge was occurring <br />~ over a one mile stretch beginning two miles below S.H. 13. This <br />~ cannot be conclusively stated for three reasons: (1) there were <br />• ~ ~no consistent iield data Lu lnulcar.e chat ground-water iiis.ciiazge <br />was occurring at any point, (2) the amounts involved are so small <br />- as to be nEar the confidence limits of t'^e field techniques, and <br />° (3) changes in channel storage, if present, could not be fully <br />~ evaluated. <br />Although the above results were observed during the <br />period of this study, it is likely that results would be differ- <br />; ent during another Deriod under different antcedent conditions. <br />~ The winter of 1977-78 was unusually wet, and snowmelt in the <br />~ mountains provided significant base floor into the late summer. <br />e On the other hand, the summer was normally dry. This helped <br />~ achieve steady-state conditions. However, during wet times, it <br />i is likely that Chere would be some ground-water discharge to the <br />'river. Unfortunately, a study during a wet period would be ex- <br />1 tremely difficult to perform accurately. However, if ground- <br />s <br />water discharge were occurring during a wet period, the higher <br />? . ~ river flows would provide significantly increased dilution ca- <br />pacity for any dissolved substances present in the ground water. <br />5-1 <br />