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I I I I I I I 5 by channelization, or a low cost pumping system would have to be used; however, this conclusion is based on their preliminsry study which included lowering the water table in a low lying area adjacent to the Rio Grande. I I I I I I I I I I I I The Colorado Water Conservation Board is carrying on a Vslley wide study including water salvage and related problems. Information from W. H. Sweet, local representative, indicates maximum and minimum measurements on Rock Creek of 72 and 5.5 cfs at the Alamosa-Rio Grande County line and for the Bowen Drain 92 and 6 cfs. These measurements have been taken since March 1969. Measurements for water quality taken this spring show total dissolved solids in Rock Creek as approximately 8qO ppm and in Bowen Drain as approximately 500 ppm. This information substantiates SCS findings as to water quality. The Water Resources Division of the U. S. Geological Survey has been carrying on a water resources study under the direction of Philip A. Emery. While much of the information gathered is preliminary and subject to revision it is indicative of conditions that may be expected in the area of the proposed Rock Creek channelization. Preliminary findings indicate that the part of Rock Creek considered in this report is in a drainage area having high to very high conductivity with medium alkali hazard and medium to high salinity hazard. Recommendations for Desi~ For a design basis a consistent slope of S = 0.00086 has been used. This figure was developed by dividing the total length (90,000 feet) of the proposed channel into the difference in elevation of the two ends. Actually this grade may be decreased somewhat in design to decrease the back water effect of the Rio Grande. The decrease will be of such small magnitude that there will be little effect on the capacity calculations shown below. The proposed route for channelization is approximately 17 miles. The channel as it exists at this time is approximately 35 miles between the Alamosa-Rio Grande County line and the Rio Grande. Information available at this time indicates that no problem will develop in regard to water quality. The channel should be designed to handle not less than 175 cfs under normal conditions. As the channel will be expected to act as a drain for the adjacent area an average depth of eight feet is recom- mended. At this depth the bottom of the drain throughout its length should be below the clay and in sand and gravel according to SCS soil profiles, which is to be desired. 0580