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... __, ~ ..:"'-t -" '-, ,-..... Permeabil ity, texture, and depth.are major soil characteristics that affect the volume of water passing through the profile and carrying salt to the river. The combined effect of these characteristics determines the moisture holding capacity of the soil. Combinations of intake rates and moisture holding capacity were developed to show which irrigated soils might be considered as significant contributors to the salt loading problem. The soils were grouped by three classes of intake and three classes of moisture holding capacity. Those soils with high intake rates and low moisture holding capacity are considered to contribute most significantly to salt loading while those with low intake and high moisture holding capacity are not so critical. These combinations, the acreages of soils involved, and the effect on salt loading classified as severe, moderate, and sl ight are shown in Table 1. A more detailed listing by mapping units identified the more critical soils and is shown in Table 2. In addition to soil characteristics that contribute to seepage and deep percolation, the on-farm inventory in 1976 identified about 1,600 acres of cultivated land that has become water-logged due to poor subsurface drainage conditions. RANGE LAND The upland watershed of tributaries draining into the river in Grand Valley encompasses 839,000 acres with 175,000 acres (21%) in private ownership and 664,000 acres (79%) of publicly owned land. Currently more than 700,000 acres (83%) is considered to be in fair or poor condition and in need of improvement. An assessment of the potential for improvement shows 540,000 acres (64%) can be brought up to good or excellent condition and all poor conditions can be eliminated. See Table 3 for additional details. Similar conditions for the privately owned land are shown for individual range sites in Table 4. 13