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State Req. <br />defined stream channel. However, there are a few small springs which • <br />supply water. This area lies within the Fish Creek Drainage Basin. <br />Within a two-mile radius of the mine, the main drainages (Grassy Creek <br />and Fish Creek) are somewhat different. As shown in Exhibit 7-3, Grassy <br />Creek, as it flows out of the northern part of the permit area, enters a <br />narrow valley with the channel becoming incised. Very little alluvial <br />material is present in this valley with the bulk of material being col- <br />luvium. The Fish Creek drainage, which is in the southern part of the <br />permit area, widens into what is known as Twentymile Park. Beaver <br />dams along Fish Creek periodically block the drainages. <br />iv. Agricultural Significance of Alluvial Soils <br />The alluvial soils at Seneca II have formed from mixed fine textured <br />alluvium. Typically, the surface layer is dark gray clay loam. The <br />underlying material is stratified clay ranging in color from light gray to <br />dark grayish brown extending to 60 inches or more. Sixteen soil samples <br />were collected from five different profiles and analyzed for various • <br />constituents including clay content. Clay percentages ranged from 29 to <br />47 percent and had a mean of 40 percent. <br />The alluvial soils at Seneca II are unsuitable for cultivated croplands due <br />to climatic and hydrologic limitations. Based upon chemical properties, <br />these soils have few limitations for crop production. However, these <br />soils at Seneca Il are in the colder region of Routt County at elevations <br />ranging from 6550 to 7050 feet msl. The soil temperature class is cryic <br />and the growing season ranges from 40 to 75 days. Because of the short <br />and cool growing season, it is unlikely that these soils will economically <br />produce sustained high yields of crops when treated and managed accord- <br />ing to acceptable farming methods. Cultivation would also be inefficient <br />and unernnomical due to the small elongated parcel size of the areas. <br />The soils are best used for livestock grazing and wildlife habitat. <br />A potential flood irrigation water source is Grassy Creek. However, this • <br />irrigation water has a conductivity of greater than 750 micromhos/cm. _ <br />The salinity hazard is classified as very high (USDA, 1969). High salinity <br />7-7-6 <br />l~vised 5/27/81 <br />