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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />4 <br /> <br />The tentatively proposed route of the channelization is such that all <br />decreed pointa of diversion affected will be served. It is possible tbat <br />the location of channelization could be improved if proviaion were made to <br />change some points of diversion. Tbis mattsr should be considered more <br />thoroughly when field work is done for final plsns. <br /> <br />A second problem that will be reflected in conatruction costs is that the <br />area is waterlogged and excavation will almost surely be done from mate <br />which will result in a relatively high unit cost. Without question con- <br />struction could be done for the least cost during dry periods or while the <br />ground is frozen, if equipment of sufficient aize to bandle the frost ia <br />used. This condition will adversely affect access to the work. While this <br />can be considered as a problem it will bs normal for most drainage and <br />channelization projects in the San Luis Valley. <br /> <br />A third problem will be that moss and other vegetative growths will occur <br />in the channel because of low velocities. Normal velocities that can be <br />expected will range from 0.6 to 2.0 feet per second. Any velocitiee in <br />excess of two feet per second will occur only during periods of high runoff. <br /> <br /> <br />Other Studies <br /> <br />As early as 1822 the San Luis Valley had attracted notice and by 1852 the <br />value of water in the Valley was recognized sufficiently so Uwt the first <br />decree waa granted. Rock Creek has been mentioned specifically in reports <br />dating back to the early part of the century. In generalities the channeli- <br />zation bas been known to be desirable for the past two generations, at least. <br /> <br />Interest generated by the District caused Soil Conservation Service to <br />present, on a reconnaissance basis, the results of their atudy of Rock Creek <br />made in late 1967. The Soil Conservation Study included a portion of Rock <br />Creek in Rio Grande County and all of Rock Creek in Alamosa County, alao a <br />low lying area along the Rio Grande in Rio Grande County. In an attempt to <br />uae some figuree developed in the Soil Conaervation Service atudy it was <br />determined that the preaent report ia based on a preliminary study of approxi- <br />mately one-half the area of tbat covered by the SCS etudy and report. <br /> <br />Soil Conservation Service took 12 water samples to determine the quality of <br />the water that might be salvaged. The average reaults were 614 ppm total <br />dissolved solids of which 14.35% waa sodium. This would indicate an acceptable <br />qnality of water. A general aoils classification by SCS indicated clay deptha <br />up to aix feet in a saturated area where the water table varies from one to <br />six feet belaw the surface. The clay is underlaid with sand and light gravel <br />in which one would assume a high storage coefficient and good transmissibility. <br />The conclusion of SCS is that either the Rio Grande would have to be deepened <br /> <br />0581 <br />