Lahontan Reservoir is a major recreational site in the Carson River basin in western Nevada. The reservoir is fed by the Carson River and by the Truckee Canal which transports water from the adjacent Truckee River. Water quality in both rivers is influenced by agriculture and urbanization. Specific conductance tended to increase in a downstream direction. Generally, pH values ranged from 7.0 to 8.8. Dissolved-oxygen concentrations were greater than 5 milligrams/L. Calcium and sodium were the dominant cations and bicarbonate the dominant anion. Suspended-sediment concentrations ranged from 3 to 1,790 milligrams/L. Ultimate carbonaceous biochemical oxygen demand ranged from 1.2 to 19.6 milligrams/L. The codominant algal groups were the blue-greens, greens, and diatoms. Background total nutrient and suspended-sediment loads were about 490 tons nitrogen, 130 tons phosphorus, and 200,000 tons suspended sediment. Total nutrient and suspended-sediment loads to Lahontan Reservoir were about 980 tons nitrogen, 300 tons phosphorus, and 300,000 tons suspended sediment. Loads to the lower Carson River from the reservoir were about 820 tons total nitrogen, 180 tons total phosphorus, and 26,000 tons suspended sediment.
