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<br />-24- <br />2. Scullion Gulch <br />Geomorphic Characteristics <br />Scullion Gulch is an ephemeral stream which crosses the lower southwest <br />portion of the permit area, draining to the White River. the confluence of <br />Scullion Gulch and the White River is also within the permit area. <br />Scullion Gulch receives drainage from the southwestern and southcentral <br />portions of the permit area, as well as from adjacent lands to the west. <br />Scullion Gulch is approximately one-tenth the size of Red Wash, draining an <br />area of 11.7 square miles. Approximately half of the drainage area exists <br />within the permit area. Map 102 identifies the alluvial deposits mapped by <br />the permittee along Scullion Gulch. The deposits typically range between 50 <br />and 200 feet in width, with a depth of about 15 feet. The deposits were <br />mapped by the permittee to a point approximately 1/4 mile upstream from the <br />permit area, where they become discontinuous. At this location, the deposits <br />do not appear to extend any further up the drainage. The permittee again did <br />not quantify the amount of land area occupied by the deposits; however, based <br />on Map 102 it appears the alluvial deposits occupy a few hundred acres. <br />Scullion Gulch is incised into both the upper sandstone facies and a portion <br />of the middle sandstone facies, both of which are waterbearing rock units. <br />Five stock-watering ponds exist along Scullion Gulch. As in Red Wash, the <br />ponds serve to retain water for stock purposes until it is lost to seepage or <br />evaporation. They do not hold water year round. <br />Based on the width and areal extent of alluvial deposits along Scullion Gulch, <br />the drainage generally meets the geomorphic criteria and therefore qualifies <br />for further consideration as an alluvial valley floor. <br />Water Availability Criteria - Artificial Flood Irrigation <br />As with Red Wash, flow events along Scullion Gulch were monitored using a <br />crest stage gage. During the two year inventory period conducted by the <br />permittee, only three runoff events were recorded, the highest event measuring <br />185 cfs. Again, however, crest-gage data has only limited application for AVF <br />purposes. The mean annual yield estimations provided by the permittee are <br />more applicable for identifying the amount of water which may be expected for <br />Scullion Gulch. The permittees' estimations, derived using Grunsky's formula, <br />indicate that the potential average annual water yield from the Scullion Gulch <br />watershed is 202 acre feet. This corresponds to approximately 0.34 inches of <br />runoff. The amount of water available annually, as estimated through this <br />method, indicates that Scullion Gulch warrants further consideration as a <br />potential alluvial valley floor. <br />Subirrigation <br />As with Red Wash, the presence of subirrigation along Scullion Gulch was <br />investigated by the permittee based on the type of vegetation present along <br />the drainage. The permittee has identified a big sage brush - greasewood <br />community along the entire length of unconsolidated alluvial deposits <br />identified on Map 102, and concludes that water is available to the vegetation <br />"on a limited and sporadic basis". The big sage brush-greasewood community, <br />however, is more sparse compared to that community found along Red Wash, <br />