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point. These factors were determined by normalizing the local volumetric runoff (local area times <br />local average precipitation) by the corresponding incremental runoff. The incremental runoff was <br />determined by taking the difference of the total volumetric runoff between successive USGS gage <br />locations. <br />The gain approach was used as the default technique in the White Model. However, at several <br />locations, the prorated hydrograph developed using the gain approach showed an attenuated shape <br />that was not representative of a "natural" hydrograph. This occurred predominantly in the headwater <br />areas where the hydrograph is dominated by runoff from spring snowmelt. In these situations, the <br />nearby gage approach was used. For the nearby gage approach, the proration factor was determined <br />as a function of a stream gage in a neighboring tributary, by comparing the local volumetric runoff. <br />This procedure was applied on Coal Creek, Miller Creek, Big Beaver Creek, Elk Creek, Flag Creek, <br />Black Sulpher Creek, Soldier Creek, Lake Creek and Evacuation Creek. Details concerning these <br />cases can be found in Appendix B. The final proration factor file (whiteT.rib) for the StateMod <br />implementation for the White River basin can be found in Appendix A (http://cdssstate.co.us). <br />Phase IIIa enhancements, which impact the baseflow file, include the reevaluation and revision of <br />drainage areas and average precipitation data at selected locations. In addition, a new baseflow was <br />added at Evacuation Creek. Appendix D, Section D.13 describes these Phase IIIa enhancements. <br />River System 4-5 <br />