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10,400 ton/yr in the Colorado River at Hot Sulphur Springs was 53 percent of ~ the estimated total annual salt load of 19,500 ton/yr. The estimated base- en flow salt load of 135,000 ton/yr for the Eagle River 'was 89 percent of the ~ estimated total annual salt load of 151,200 'ton/yr. ,The estimated base-flow C) salt load of 183,000 ton/yr for the Roaring Fork River was 59 percent of the estimated total annual salt load of 308,100 ton/yr. The estimated base-flow salt load of 255,000 ton/yr for the Colorado River at Dotsero was 59 percent of the estimated total annual salt load of 431,300 ton/yr. The estimate of total annual salt load reported by BLM for the Colorado River below Glenwood Springs did not include the effect of the hot springs discharge of the Dotsero-Glenwood Springs group. If the effect of the hot springs is added to the estimate reported by BLM, then the estimated total annual salt load for the Colorado River below Glenwood Springs is 1,117,300 ton/yr. The estimated base-flow salt load of 974,000 ton/yr accounts for 87 percent of the estimated total annual salt load (the hot spring's effect plus the BLM est.mate) for the Colorado River below G1enwood Springs.' Gunnison Subregion The drainage area of the Gunnison River basin is about 8,000 mi2 (fig. 1). Annual precipitation, mostly snow, ranges from about 20 to 50 in. in the areas above 9,000 ft. Annual precipitation ranges from about 8 to 20 in. in the remainder of the basin below 9,000 ft. The Gunnison River is the largest tributary to the Colorado River in Colorado. The headwaters of the Gunnison River are near Gunnison in high mountainous terrain. The headwaters are generally less than 100 mg/L in dissolved-solids concentration. By the time the Gunnison River has neared Delta, the mean annual dissolved-solids concentration in the river has increased to about 400 mg/L. The Uncompahgre River enters the Gunnison River at Delta. At its mouth the mean annual dissolved-solids concentration of the Uncompahgre River is about 1,200 mg/L. This is caused by both natural sources and man's activities. During most of the irrigation season, all flows in the, Uncompahgre River are diverted for irrigation and only irrigation-return flows enter the Gunnison River. At its mouth the Gunnison River has a mean annual dissolved-solids concentration of about 600 mg/L. The average discharge of the Gunnison River at its mouth is about 1.7 million acre-ft/yr. This discharge is about 200 acre-ft/mi2. Flow in the Gunnison River is regulated by Blue Mesa and Morrow Point Reservoirs. Blue Mesa Reservoir has a capacity of 830,000 acre-ft, and Morrow Point Reservoir has a capacity of 121,000 acre-ft. The combined storage capacity of the two reservoirs is equal to about 1.7 times the mean annual discharge of the Gunnison River near Gunnison, Colo. Both reservoirs generate power and provide downstream requirements under the Colorado River Compact. Measurements of specific conductance and stream discharge at 38 sites were made in the Gunnison subregion (fig. 10). At 25 of the sites, samples were collected for chemical analysis. Two linear regression analyses of specific conductance measured at the sites versus dissolved-solids concentrations determined in the laboratory were made on these data and then used to 32