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<br />.~"'.,.', <br /> <br />.~ Return Flow <br />d' <br />~" Return flow from diversions of non-project land from the Los Pinos <br />0J and San Antonio Rivers was determined by the inflow-outflow-diversion <br />t.:> method and by the consumptive use method. It was found to be 40 percent <br />. c.) of diversions. For the non-project land diverting from the Conejos River <br />and using the consumptive use method, it was found that 30 percent of the <br />diversions could be expected to be return fl~ff. <br /> <br />Records of outflow, inflow, and diversions for the Conejos River <br />proper indicate that past return flow amounted to almost 38 percent of <br />diversions. Graphs of return flow show it returned to the stream approxi- <br />mately 15 days after application. They also show that vdth a meager to <br />average supply the return flow is somewhat less than 30 oercent, increasing <br />as the supply increases. In years of above normal supply, part of the <br />rcturn flow indicated by the inflow-outflaw-divcrsion nethod is actually <br />surface waste. Using all data available, a return flow of 30 percent was <br />selected for project conditions and is considered reasonably accurate. <br /> <br />Reservoir Evaporation and Other Losses <br /> <br />Evaporation from the various reservoirs used in the studies was <br />detemined by standard methods, i.e., correcti.ng gross reservoir evapora- <br />tion by effective precipitation or by consumptive use, whichever was <br />applicable at the selected site. <br /> <br />The only reservoir studied from which non-recoverable losses other <br />than evaporation might be expected was Mogote Reservoir. Here, allowance <br />was made for non-recGverable losses seeping into the dry cone below the <br />reservoir and surrounding aroa. <br /> <br />Reservoir O?erations <br /> <br />Irrif~tion. The natural flow a~d redivertible return flow in the San <br />Antonio, Los Pinos and Conojos Rivers below the reservcirs on the Conejos <br />River were used to supply the non-project lane' requirements as reflected <br />by past diversions. ~~y eXce~s was applied toward meeting the demands of <br />the project. When this natural flow and return flow below the reservoir, <br />or reservoirs investigated, was inade~uate to meet the demand, the natural <br />streamflow of the CDnejos River or stored reservoir water was used to meet <br />the defiCiency. j,llowance was made in the final studies for that part of. <br />the water in each month which could net be utilized in meeting demands <br />lcecause of its erratic n'lture; also, allcwance was made for operational <br />waste which necessarily occurs in any irrigation system. Operation studies <br />were made for various capacities of the Platoro, Counsellor, Jaques, and <br />Platoro-Mogote comhin'ltion of reservoirs. The Counsellor and Jaques sites <br />proved to be too costly and have t>een ahandoned. Operations at the PIa toro <br />and Flatoro-Mog~te comhination were used in ~on:uncti~n with. economic <br />studies to determine the selected reservoir car'acHy of 60,000 acre-feet a'c <br />tte Platoro .Resec'yoir site. l'he shortRges illdie.2ted hy the principal ope;:".. <br />tion stUdies, in percent of ide~l demand, are depicted graphically on Plate <br />B. The selected reservoir will provide an average of 94.6 percent of the <br />ideal supply. Shortages at this reservoir, which would have been experie!rcsd <br />in the 1903-1945 period, are tabulated: <br /> <br />24 <br />