Laserfiche WebLink
• <br />(- <br />~:-- <br />Assuming that it would take one week to implement our mitigative <br />plans, we could expect about a 10% loss in streamflow. This '.vas based <br />on analysis of Upper Dry Fork gaging station for water year 1478: the <br />closest to an average water year on record. In that year less than <br />56b of the water yield was captured for release during July, August <br />and September. So the lOp lass in streamflow would be of little con- <br />sequence. In a dry ,year when al] the flow is captured in Minnesota <br />Reservoir a 10% loss in streamflow would be significant. Water <br />augmentation would be necessary to make up for this loss. <br />Since there is no water storage on other streams found on the lease, a <br />worse case scenario of mine subsidence impacts on streamflow would be <br />if a total loss of streamflow occurred during the irrigation season on <br />South Prong or Horse Creek (the irrigation season is assumed to cover <br />the entire months of July, August and September). Assuming that it <br />would take one week to implement our mitigation plans and that the <br />loss occurred during the week having the highest flew during the irri- <br />gation season, during an average year one could project a loss of 27% <br />or 75.5 acre feet from South Prong, and a Toss of 19% or 28.9 acre <br />feet from Horse Creek. These estimates were based on data from water <br />year 1978: a wetter than normal but closest to average water year on <br />record. The week having the highest flow on all sites was the first <br />week in July. This is not considered to be the peak irrigation <br />season. Also, the chances of subsidence impacts appearing during the <br />peak flow period or resulting in total loss of streamflow are rare. <br />Thus, the figures represent a worse case situation. In a dry year the <br />volumes involved would be much lower. In any event, any water loss <br />would be made up through water augmentation. <br /> <br />~n1 <br />