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6 ANALYSIS AND DISCUSSION Evaluation of River Water Supplv to Water District 2 Ditches Study of 10-year moving averages for ditch diversions under direct flow decrees reveals considerable differences in trends from upstream to downstream in Water District 2. Whereas the grand sum of ali diversions of direct-flow water shows very little trend characteristics, individual ditches or ditches in particular section's of this region of the South Platte River show very pronounced trends. Clear Creek to Henderson Two ditches (Fulton and Brantner) divert water from the reach of the South Platte River between the mouth of Clear Creek and the Henderson gaging station. The general pattern of diversions in this reach corres- ponds with the inflow into the area as measured at the Denver gaging station plus the Denver sewage plus the infiow from Clear Creek. However, the reduction in diversions during the drought years of the 1950's and 1960's was more severe than would be expected due to the reduction in inflow of water into the section caused by the low runoff conditions. Another interesting feature is that the peak ten years of diversion ended in 1952 whereas the peak inflow above these two ditches occurred during the 10-year period prior to i949. This offset in timing may not be sig- nificant and at this time is unexplained. \ Henderson to St. Vrain Creek " The majority of ditches in Water District 2 divert from the reach between the Henderson gage and the mouth of St. Vrain Creek. Diverting to the west are the Lupton Bottom, Meadow Island No.1, Beeman, Meadow Island No.2, and Jay Thomas Ditches. Diverting to the east are the Platteville, Platte Valley, Farmers Independent, and the Western Mutual Ditches. The pattern of the total diversion of direct-flow water by ditches between Henderson and the mouth of the St. Vrain is very similar to the pattern of flow at the Henderson gage. As in the upper reach, diversions of direct-flow water in this section during recent years have been less than those of the 1930's, although the inflow at Henderson was comparable for the two periods. The shift in peak of the maximum 10-year diversions is also 3 to 4 years later than the peak 10-year flow at the Henderson gage. St. Vrain Creek to Bic Thompson River The two major ditches which divert water in this section of the South Platte River, both to the east side of the River, are the Union Ditch and the Godfrey (Section 3) Ditch. ^ 10-year moving average of the sum of the diversions of these two ditches shows a pronounced upward trend in diversion of direct-flow river water. It appears that these two ditches are currently enjoying 5- to 7,000 acre-feet more direct-flow water per year during recent years than during comparable periods prior to 1950. This increase is, at least in part, due to increased return flows generated by the Colorado-Big Thompson Project water applied in the St. Vrain Creek and Big Thompson River areas. ,