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a lesser extent, chloride. Bicarbonate appears to increase proportionately during high runoff periods, while sulfates are significant in early spring, but are less prevalent during other periods of the year. Turbidity could be expected to increase during spring runoff as increasing stream flow is correlated with increasing sediment load. Overall turbidity values ranged from 4-40 Jackson Turbidity Units (JTUs) and are considered low. Stream quality factors that significantly affect or are affected by biological processes are nitrates, phosphates, dissolved oxygen, coliforms and biochemical oxygen demand. Nitrate and phosphate concentrations appear to be relatively small throughout the watershed and fluctuate markedly. During spring months when snowmelt begins to feed the streams in the area, the runoff is rich in nitrogen and probably phosphate as it drains areas where cattle and sheep have been feeding during the winter. Streams is the Trout Creek drainage area are classified B by the Colorado Department of Health (1974). This class- ification means local streams are suitable for all purposes for which raw water is customarily used, except primary contact recreation, such as swimming and water skiing. In addition the water in Class B streams has: (1) a geometric mean of leas than 10,000 total coliform groups, or 1,000 fecal coliform groups per 100 ml sample, (2) a dissolved oxygen content of at least six mg/1, (3) a pH rating of no more than 9.0 nor less than 6.0 units, {4) a temperature which maintains a normal pattern of diurnal and seasonal fluctuations, and is not increased above 20°C by any other than natural means, and (5) no increases in turbidity of over ten JTUs during any single period (Colorado Department of Aealth 1974). The highest fecal coliform value recorded for the analysis area vas 220 (probably bacterial) groups per 100 ml. The S-day BOD ranged from 1.5 to 2.0 for the S~