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. ~ tv I-' o ill . ','<ll4. f>.'- /-,,, these results agree very well with aggregated results of other stuclies, but the incliviclual agricultural loacling values tencl to be much smaller. This is due to the fsct that the agricultural salinity contribution was basecl solely on concentrating effects. Natural runoff contributes 52 percent of the salt loacl from the Upper Basin (EPA, 1971). In an effort to control any salinity effects due to soil c1isturbsnce by livestock grazing and energy development in the basin, the Bureau of Lancl Management is pursuing a program of more restrictive grazing controls, intarseeding of contour furrows, ancl chaining and .eecling to control salinity from surface hyclrologic events (Bently et al. 1978). Much of this program is basecl on work by Gifford et al. (1975) in the Price River area. ''': . '. Ponce. (1975).,and Ponce et .al. (1975) reportecl onnonpoint salt loading from grazing ancl its effects on ManCos Shel'esin.e1lit'Price .River.Bas.ih. '.'\,"h'itmore(1976) ancl White (1977) reported on the' salinity aspects oi Mancos soils ancl the effect of micr'o'channels, respe1t.t;!.veJ.').',. All of'fhese'iltudies basically concludecl that a practice which compacts or otherwise disturbs the sOLl structure, reduces infiltration and increases runoff and/or erosion on saline soils will increase salt yields. Similar results were obtained by Laronne and Schumm (1977) for the Grancl Valley area. Thomas (1975) investi- gated the use of gully plugs ancl contour furro"Ws to control erosion and hacl good success. ~k"~orter ancl Skogerboe (1979) investigatecl interflow as a transport mechanism for salt on Mancos soils, ancl c1eterminecl that it had little effect. The general consensus of investigations on nonpoint diffuse sources of salinity in the UCRB is that measureS such as grazing controls, contour furrow and strict regulation of roacl and site development, construction of energy exploration activities will recluce man~causecl salinity from these lands. However, the extreme natural variation in hydtoldgic events, stream 'and reser- voir evaporation and other "buffering" effects will tencl to mask the relative magnitude of these programs. Economic Damages Caused by Salinity The salinity levels expressed as total dissolvecl solids concentration or electrical conductivity may not aclequately reflect the impacts on specific users. Domestic users are primarily concerned with.harclness caused by calcium and msgnesium. The important salinity constituents for industrial users, such as electrical power plants are primarily calcium carbonates ancl sulfates. Calcium carbonate is often the first salt to precipitate in recirculating cooling tower water and high levels can increase the amount consumecl ancl/or trutecl. The costs associatecl with using water impaired by high salinity levels are imposed on inclustrial, domestic and sgricultural users. Industrial and domestic costs are associated with e~tra costs of treatment and softening, and with premature replacement of plumbing) boilers" water heaters, ,etc._ Domestic. c1amages can also be experienced by loss of lanclscapes with low salt tolerance. Estimatscl costs clue to salinity increase in the Los Angeles area have been reported by Eubanks ancl d'Arge (1976), Lawrence (1975), and Tihansky (1974). 33 . .