WSP06567 - Laserfiche WebLink

Home Browse Search

1\ ;.,-, 3 .., C' UlUaJ'lU . . . are also available throughout the 1976 through 1982 period for the Mancos River near Towaoc, located 0.1 mile upstream of the bridge on Highway 666. The river distance between the two gages is approximately 20.2 miles. A comparison was made of the flow records on a daily basis at the two gage locations to determine the amount of gain or loss. The following criteria were used in the comparison: I. Days when the flow of the Mancos River was greater than 20 cfs were excluded from the comparison because such flows were normally the result of rainstorms or snowmelt runoff within the basin. Thus, at higher flow rates there was a greater chance that the river gain or loss was affected by significant tributary inflow between the two gages. 2. Days when the flow of the Mancos River at Highway 666 was less than 1.0 cfs were also excluded as flow rates of this magnitude are roughly equivalent to a dry stream condition. Accurate stream loss estimates could not be made on such days. 3. As described in Section VI, irrigation diversions from the Mancos River bypass the gage at Highway 666. Since the gage records do not take into account the flows associated with the ilTigation diver- sion, a compensating correction was made in the analysis. A comparison of the river flows at the Johnson Canyon gage and the Highway 666 gage is presented in Table 11. Water consumption by phreatophytes and evaporation during the months of March through June is probably greater than indicated in the table, since there may be a substantial amount of tributary inflow between the two gages during this period. -30- j;