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During August 1985, a series of 19 alluvial hole's were • <br />drilled down to the bedrock layer in the canyon to further identify <br />the alluvial characteristics. Mapping of the valley bottom <br />deposits was conducted in September 1985 anci presented on Map 14, <br />Apache Canyon, Ciruela Canyon Surficial Geology, in plan view and <br />Map 15, Apache Canyon, Ciruela Canyon Cross Sections, in profile. <br />As indicated, bedrock ranges from 12 to 17 feet below the surface <br />with upper material consisting of topsoil and colluvial deposits. <br />Horizontal extent of the material is limited to the valley bottom <br />which is generally 100 to 300 feet wide and generally corresponds <br />with the tree line of the slopes. Topsoil ranges in thickness from <br />12 to 70 inches and is generally a loam to silty clay loam. <br />colluvial underlying materials are subangu:Lar to angular sands, <br />gravels and shales. <br />In June 1985, WFC excavated 4 backhoe pits in Apache <br />Canyon to determine the presence or absence of sub-irrigation. Pit <br />locations are shown on Map 14, Apache Canyon, Ciruela Canyon <br />Surficial Geology. Presence of an aquatic moisture regime or • <br />reducing zone was the criteria used to evaluate sub-irric~ation. <br />Evidence of a reducing zone less than or equal to 6 feet from the <br />surface would indicate subirrigation; unless soil color and <br />mottling in the rooting zone indicate vegetation was not relying on <br />or enhancing vegetation. The investigation revealed a reducing <br />environment is not present within 6 feet of the surface and as <br />such, subirrigation is not a phenomenon in ;4pache Canyon. <br />With the above description of the valley bottom, an <br />alluvial valley floor determination was made. As per the Division <br />definition, "Alluvial valley floor means the unconsolidated :;tream- <br />laid deposits holding streams with water availability sufficient <br />for subirrigation or flood irrigation agricultural activities but <br />does not include upland areas which are generally overlain by a <br />thin veneer of colluvial deposits composed chiefly of debris from <br />sheet erosion, deposits formed by unconcentrated runoff or slope <br />2.06-2c <br />• <br />(Revised 04/27/94) <br />