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-35- <br />WECC presented a projection of depletions to the Colorado River System <br />to quantify impacts on aquatic species. This information was requested <br />by the U.S. Fish and Wildlife Service (Windy Gap Study). The results of <br />WECC's study showed a net depletion of 13.1 ac-ft per year from the <br />North Fork of the Gunnison River. This is a small depletion in <br />relation to the size of the mine and in comparison to the flow in the <br />North Fork of the Gunnison River. <br />MINNESOTA CREEK DRAINAGE EVALUATION <br />As part of its initial permit review MLRD evaluated preliminary <br />hydrologic characteristics of Minnesota Creek drainage. Subsequently, <br />WECC withdrew its request to mine or affect this drainage basin as part <br />of its mining permit. Therefore, WECC will not affect this area and <br />consequently MLRD no longer needs to consider this drainage in its <br />impact assessment. The following discussion is for informational <br />purposes only, and may give abetter understanding of issues that will <br />need to be addressed in later permit terms. <br />Minnesota Creek drains approximately 53.5 square miles. A small part <br />of this drainage system lies within the Mt. Gunnison coal lease <br />boundaries. Water is diverted from Little Gunnison Creek to the <br />headwaters of the Dry Fork of Minnesota Creek via Deep Creek Ditch. <br />WECC has placed a water stage recorder and an 18-inch Parshall flume on <br />the ditch and has measured flows for this transbasin diversion from <br />June 1971 to December 1919. Unfortunately, the time period chosen for <br />the data recorded reflects drought conditions. In addition the <br />location of the site was not the most desirable since activity by <br />beavers caused backup and flooding of the flume. It appears that for <br />the time of record reported by WECC, as well as for past ditch records, <br />approximately 1,000 acre-feet of water transferred into Minnesota Creek <br />annually. <br />A major outflow from Minnesota Creek is through irrigation ditches. By <br />consulting the straight-line diagram as compiled by WECC, it was <br />concluded that irrigation ditches annually remove approximately 20,000 <br />acre-feet. <br />Table 9 illustrates the approximate mass balance for the Minnesota <br />Creek watershed. Once again, it should be noted that on a mean annual <br />analysis, an excess amount of water exists within the watershed <br />boundaries. However, during the months of May through September, a <br />deficit occurs. This implies that any alteration.of the hydrologic <br />characteristics of the watershed should be carefully monitored to <br />insure minimal impacts will occur during dry months. <br />Table 9 Minnesota Creek mass balance analyses (all units in AF). <br />Inflow <br />Precipitation <br />Mean Annual <br />71,000 <br />~: <br />Mean May-September <br />22,000 <br /> <br />