Groups of Lahontan Cutthroat Trout were tested in Pyramid Lake water which was altered with the addition of the sodium salts of sulfate, chloride, carbonate and bicarbonate, to simulate conditions in the lake as the lake volume decreases. Trout tested at 50F for 14 days would tolerate an environment representing up to 2 1/2 times the present salt concentration but would not tolerate 3 times the present salt concentration. The former environment (2.5X concentration level) represents what will occur when the lake reaches 3660 feet above sea level. Therefore, Pyramid Lake should be maintained as much above this elevation as possible to protect the fishery. (Author)