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XVIL Operations on Alluvial Valley Floors <br />The permit area and adjacent lands contain three stream channels - the White River, Red <br />Wash, and Scullion Gulch - with enough associated alluvium to be considered as potential <br />alluvial valley floors. All three channels cross the permit area as well as the adjacent area. <br />The permittee's alluvial valley floor analysis is contained in Section ILD of the permit <br />application. <br />Below is a detailed consideration of the alluvial valley floor potential of each of the <br />following three drainages: Red Wash, Scullion Gulch and the White River. <br />Red Wash <br />Water Availability Criteria - Artificial Flood Irrigation <br />The permittee estimated the potential average annual water yield from the Red Wash <br />drainage basin using Grunsky's Formula (Grunsky 1908, Sellars, 1965; see bibliography in <br />permit application). The estimate indicates that an average of 2,090 acre feet of water <br />could be made available annually in Red Wash. This corresponds to approximately 0.32 <br />inches of runoff, which is about 3.5 percent of the annual precipitation falling on the area. <br />Actual measurements of flow on Red Wash have been made using a crest stage gage <br />station located at the mouth of the basin. With the crest stage gage approach towards <br />stream monitoring, only peak flows that occur between monitoring intervals are recorded. <br />Flows that occur at less than the peak flow during any one monitoring interval are not <br />recorded. The crest gage method is therefore useful for recording peak events only; the <br />method has limited application for determining duration of flow and hence flow volumes <br />which occur during the monitoring interval. <br />The results of the crest gage monitoring efforts on Red Wash indicate that flow is almost <br />entirely in response to snowmelt and storm rainfall events. A total of six runoff events <br />were recorded during the two year inventory period conducted by the permittee. Events <br />that occurred during the fall and summer months resulted from thunderstorm activity; <br />however, peak flows during the year were greatest during the spring as a result of <br />snowmelts. The largest event recorded for Red Wash during the inventory period was 240 <br />cfs, which was generated as a result of late winter snowmelt. Because of the nature and <br />intent of crest gage type flow monitoring, it has limited usefulness for identifying water <br />availability criteria necessary for alluvial valley floor interpretation. Therefore, the most <br />useful information supplied by the permittee for AVF purposes is the estimation of <br />average annual streamflow calculated through Grunsky's Formula. The amount of water <br />available annually, as estimated through his method, indicates that Red Wash further <br />qualifies as a potential alluvial valley floor. <br />In response to requirements for additional information (Stipulation No. 8), the permittee <br />prepared and submitted a report entitled "Red Wash Drainage Basin Alluvial Valley Floor <br />Study" to the Division on July 27, 1983. The emphasis of the report was to provide <br />