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identified in Task Memo 2.09 -12, "Consumptive Use Model Non - Irrigation Consumptive <br />Use and Losses in the Yampa River Basin." <br /> L <br />• Three aggregated municipal and industrial (M &I) nodes were added to represent 8,163 of of <br />consumptive use not explicitly modeled in Phase II. This use represents all consumptive use <br />exclusive of irrigation diversions, trarismountain diversions, and evaporation from reservoirs <br />and ponds, as identified in Task Memo 2.09 -12, "Consumptive Use Model Non - Irrigation <br />Consumptive Use and Losses in the Yampa River Basin." <br />• Consumptive use on the Green River within Colorado was added to the model as one <br />aggregated node. This improvement assures that the model represents all use in Colorado <br />above the Green River at the State Line. <br />• Miscellaneous refinements to the Phase H model. <br />Three data sets were developed for the Yampa Model: historical, calculated, and baseline. The <br />historical data set was used to develop baseflows and calibrate parameters such as return flows. It <br />provides results which allow the modeled hydrology to be checked against recorded streamflows <br />along with the ditch efficiencies and return flow patterns to be evaluated. <br />The calculated data set uses the historical data set as its foundation but allows irrigation ditch systems <br />and reservoirs to operate by demand. The demands are computed using the State's 1993 geographic <br />information service (GIS) cropping patterns, historical climate data, and the Blaney - Criddle <br />technique for estimating irrigation water requirement. <br />The baseline data set uses the calculated data set as its foundation, thus allowing selected ditch <br />systems and reservoirs to operate by demand. A baseline data set has been prepared which, unlike the <br />calibration data set, assumes all existing water resources systems were on line and operational from <br />water years 1975 to 1991. This baseline set is appropriate for evaluating various "what if' scenarios <br />over a long hydrologic time period containing dry, average, and wet hydrologic cycles. <br />Model Development 3 -3 <br />