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Net Water Loss Study <br />Hogue Pit Page 1 of 2 <br />PURPOSE AND SCOPE <br />The purpose of this Net Water loss Study is to estimate the pre- and post- mining <br />consumptive water uses on the property currently used as the Hogue aggregate mine. The <br />location of the property is shown on Figure 1. <br />The Net Water Loss study was requested by the Routt County Planning Department in a <br />letter dated January 10, 2002. The request was made as a portion of reviewing a request for <br />extension of the Speciat Use Permit for operation of the facility. <br />METHODOLOGY <br />Standard water rights calculations were utilized to determine net water loss. This is the <br />standard methodology utilized by the Colorado Department of Natural Resources, State <br />Engineer's Office, and accepted State-wide by water courts. It involves determining the <br />historical consumptive use and comparing it to projected consumptive use. Consumptive <br />use includes evaporation and evapotranspiration. <br />Gross evaporation applies to open water. Per the State Engineer's criteria, this is taken from <br />NOAA Atlas 33'. For the location of the aggregate mine, this is 40 inches per year. <br />Evapotranspiration is the water consumptively used by plants. This is calculated using the <br />Blaney-Griddle method for determining consumptive use for high altitude pasture grasses. <br />The acreage of land previously hayed was determined by inspecting aerial photographs <br />taken by the Soil Conservation Service (now NRCS) on August 15, 1969. These <br />photographs indicate that virtually the entire parcel was an irrigated hay meadow. A small <br />fringe along the south side of the property was not cropped. The limits of the final reclaimed <br />area will be, for all practical purposes, fully contained within areas that were previously <br />irrigated and cropped. Thus for purposes of this water toss study, pre-mining conditions <br />were considered to be 100 percent irrigated hay meadows. <br />NOAA Technical Report NINS 33, Evaporation Atlas for the Contiguous 48 United States," <br />U.S. Department of Commerce, June 1982 <br />i wW~waou.cemm..*~rma,uc <br />