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66 Soil Survey as soft chess, is maintained and enough vegetation is slow, and the hazard of water erosion is slight. The rate ' left standing to protect the soils from erosion. Loss of of water intake in irrigated areas is 1.5 inches per hour. the surface layer results in a severe decrease in The hazard of soil blowing is slight. The soil is subject productivity and in the potential of the unit to produce to rare flooding, which occurs during years of ' plants suitable for grazing. The very steep topography abnormally high precipitation. and the resulting runoff reduce the amount of rainfall Most areas are used for irrigated crops. A few areas that enters the soils. The slope limits access by are used for homesite development. This unit may livestock and results in overgrazing of the less sloping I provide wetland functions and values. These should be ' areas. The low available water capacity limits the considered in plans for enhancement of wildlife habitat production of desirable forage plants. Brush or land use conversion. management improves areas of range that are This unit is suited to irrigated row and field crops. producing woody shrubs at a level that decreases the The main limitation is the high water table. Areas extent of the preferred forage plants. Juniper competes adjacent to levees are subject to lateral seepage in wet for moisture and nutrients. On sites where the extent of years when the water level is high. Careful applications Juniper is increasing, forage production will decline of irrigation water are needed to prevent the buildup of ' regardless of the grazing management used. a high water table. Tile drainage can lower the water This map unit is in capability subclass Vile table if a suitable outlet is available. Furrow, border, (MLRA-15), nonirrigated. The Gonzaga and Honker and sprinkler irrigation systems are suitable. Maintaining ' soils are in vegetative soil group D, and the Franciscan crop residue on or near the surface helps to prevent soil is in vegetative soil group G. excessive runoff and soil blowing and helps to maintain the rate of water intake and the organic matter content. 166—Grangeville fine sandy loam, partially If this unit is used for homesite development, the drained, 0 to 2 percent slopes. This very deep, main limitation is the high water table. The rare flooding somewhat poorly drained, nearly level soil is on flood is a hazard. The high water table increases the plains. It formed in alluvium derived from granitic rock possibility that septic tank absorption fields will not ' sources. Mottles in the profile indicate a somewhat function properly. A drainage system is needed if roads poorly drained soil; however, drainage has been or building foundations are constructed. Houses, roads, improved by levees and reclamation projects. Elevation and streets should be constructed above expected flood is 5 to 50 feet. The average annual precipitation is levels. ' about 14 inches, the average annual air temperature is This map unit is in capability units Ilw-2 (MLRA-17), about 60 degrees F. and the average frost-free period is irrigated, and IVw-2 (MLRA-17), nonirrigated. It is in about 270 days. vegetative soil group A. Typically, the surface layer Is grayish brown fine sandy loam about 20 inches thick. The underlying 167—Grangeville clay loam, partially drained, 0 to material to a depth of 60 inches is stratified white and 2 percent slopes. This very deep, somewhat poorly ' gray, mottled loamy fine sand, silt loam, and fine sandy drained, nearly level soil is on flood plains. It formed in loam. In some areas the surface layer is sandy loam or alluvium derived from granitic rock sources. Mottles in loam. the profile indicate a somewhat poorly drained soil; Included in this unit are small areas of Columbia, however, drainage has been improved by levees and ' Egbert, and Merritt soils in landscape positions similar reclamation projects. Elevation is 5 to 50 feet. The to those of the Grangeville soil, small areas of Dello average annual precipitation is about 14 inches, the soils along old stream channels, and moderately coarse average annual air temperature is about 60 degrees F, textured soils that are saline-sodic throughout and are and the average frost-tree period is about 270 days. in the slightly lower landscape positions. Also included Typically, the surface layer is grayish brown, mottled are a few areas that are dissected by intermittent clay loam about 16 inches thick. The upper 16 inches of sloughs that have been filled as a result of land the underlying material is stratified, brown, mottled fine ' leveling. Included areas make up about 15 percent of sandy loam and sandy loam. The lower part to a depth the total acreage. of 60 inches is gray, mottled fine sandy loam. In some Permeability is moderately rapid in the Grangeville areas the surface layer is silty clay loam. soil. Available water capacity is moderate. The effective Included in this unit are small areas of Columbia, rooting depth of the crops commonly grown in the Egbert, and Merritt soils in landscape positions similar county is limited by an apparent water table that has to those of the Grangeville soil. Also included are a few been lowered to a depth of 4 to 6 feet through drainage areas that are dissected by intermittent sloughs that ' systems that require continual maintenance. Runoff is have been filled as a result of land leveling. Included