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axes of the Trout Crc:ek and Fish Creek anticlines which plunge to the north. Along • <br />the western limb oi' the Trout Creek anticline, the sandstone was found to be <br />approximately 200 fi:et thick. Although the Trout Creek Sandstone is a source of <br />good quality ground water, it is not an aquifer commonly used in the region because <br />of its great drilling depths (where it is not exposed) and because shallower, <br />productive, good quality water aquifers exist above it. <br />ASSUMPTIONS <br />It is assumed in the model that within the Trout Creek Sandstone outcrop area, <br />ground water is unconfined and in direct hydraulic communication (saturated) with <br />perennial streams that cross it. In actuality, the sandstone is not likely to be fully <br />saturated and in direct hydraulic communication with the surface flow, but this <br />assumption allowed the model to overestimate the potential stream losses due to <br />pumpage and simulate a worst case or most conservative approach. • <br />Leakance from the overlying stratigraphic units was not simulated in the model. <br />Leakance most likely occurs over the entire azea. Ignoring this leakance in the model <br />causes total recharge to the Trout Creek Sandstone to be underestimated, and <br />consequently, the stream loss to be overestimated. <br />In addition, pumpages from each well were overestimated. It is most likely that the <br />total yearly pumpage from each well will average {ess than 35 gpm, and that the <br />wells will not necessarily pump continuously for the entire year, as modeled. <br />Pumpage may decrease during the non-irrigation season when replacement water <br />needs and operational requirements aze low. From the above assumptions, it can be <br />seen that the model overestimates stream losses and represents aworst-case scenario. <br />2 <br /> <br />