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'Q005.3.0 Page 10 December 4, .197~ . ISSUE NO.5 <he ~iO Geeod, \ stream \ Is the confined aquifer (artesian) tributary to system and subject to administration accordingly? YES 1. U. S, Geological Survey Circular No. 18 estimates upward leakage from the confined to the unconfined aquifer in the amount of six-tenths to eight-tenths acre-feet per acre each year. 2. Circular No. 18 attributes diminishing flows of artesian springs in the valley to the increased withdrawal of water from the confined aquifer with this decline in flow estimated to be about 22,000 acre-feet per year since 1951. 3. The Circular states that it is likely that water from the Conejos River, in the reach between Mogote and Manassa, has been induced into the confined aquifer because of the reduced pressures in the confined aquifer as a result of increased pumping. 4, The bulletii1 states that apparently there is a hydraulic connection between the Conejos River and the confined aquifer along the fault and/or depositional contact of the valley fill and the volcanic San Luis Hills and that the timing of depletion and flow of the Conejos River correlate with increased withdrawal of water from the confined aquifer. 5. The confined aquifer derives its recharge supply from surface water around the periphery of the stratum of blue clay, 6, Every indication is tha t depletion from the confined aquifer has seriously affected the flows of the Conejos River, other surface streams, and the availability of water in the unconfined aquifer. 7, The fact that the confined aquifer is tributary, appro- priators from this aquifer should be required to remedy injury to ;enior vested rights, including the compact "call" at Lobatos. NO 1, The confined aquifer in the San Luis Valley is not, and historically has never been, considered a~ tributary in that it does not naturally contribute to the flow of the Rio Grande.