The reservoir created by the dam has a very large surface area, 25,760 acres (104.2 km2), and its average depth at maximum capacity is only about 20 feet (6 m), so it has a very high rate of evaporation. In 1998,  of water from the reservoir evaporated, more than any other lake in the state besides Shasta Lake, which has over 8 times the volume.
The reservoir formed by the dam has a large surface area of 25,760 acres (104.2 km²) and an average depth of about 20 feet (6 m). This leads to high evaporation rates. In 1998, a considerable amount of water from the reservoir evaporated, more than any other lake in the state except for Shasta Lake, which has eight times the volume.