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nD~1374 . . . The Mancos correction factors, as described in Table 9, are used to adjust the monthly streamflow estimates for the Mancos River, based on the 1938 through 1941 monthly flow data. A summary of the estimated virgin flow for the upper Mancos River at the West, Middle, and East gaging stations is presented in Table 10. Additional Analysis USGS records are available during the period of 1932 through 1937 for the Mancos River near Mancos, located just downstream of the confluence of West, Middle, and East Mancos rivers and prior to establishment in 1938 of the three gages used in this analysis. When a comparison was made of Mancos River near Mancos versus La Plata River virgin flows for this period, data for 1936 and 1937 supported the flow relationship shown on Figure 3; however, virgin flows for the Mancos River at Mancos for 1932 through 1935 were very low in comparison with La Plata River virgin flows. During this period, the relationship is described by the following: Mancos River Virgin Flow (1932-35) = 0.97 x La Plata Virgin Flow Since the 1932 through 1935 flow relationship is radically different from the 1936 through 1951 relationship, it was assumed that there was a significant error in measurements for the Mancos near Mancos gage. A 1934 memorandum by the USGS concerning accuracy for the Mancos River near Mancos gage includes a comment that "conditions are not favorable (at this location) for accurate records;" however, it was considered at that time to be the only feasible location to place the gage in that reach of the stream. Therefore, none of the USGS gage data for 1932 through 1937 were used in the virgin flow analysis. -28- ,.IH_