The circulation of water in Flaming Gorge Reservoir is caused chiefly by insolation, inflow-outflow relationships, and wind, which is significant due to the geographical location of the reservoir. During 1970-75, there was little annual variation in the thickness, dissolved oxygen, and specific conductance of the hypolimnion near Flaming Gorge Dam. Depletion of dissolved oxygen occurred simultaneously in the bottom waters of both tributary arms in the upstream part of the reservoir, and was due to reservoir stratification. Anaerobic conditions in the bottom water during summer stratification eventually results in a metalimnetic oxygen minimum in the reservoir.