is a
Reservoir in northwestern
Modoc County, California in the
Modoc National Forest about northwest of
Alturas . It is formed by Clear Lake Dam on the
Lost River and has a capacity of 527,000 acre feet (650,000,000 m³). The reservoir should not be confused with
Clear Lake , a large natural lake on
Cache Creek in
Lake County, California .
The original
Dam was constructed of rockfill and was completed in 1910. It was tall from the bottom of the foundation to the crest, if measured from the crest to the original streambed. It was replaced with a
Concrete dam near the old dam in 2002. The old dam had deteriorated and the water level was kept low to prevent it from failing. Its crest is at the same height as the old dam and the reservoir's capacity is about the same. There is a small
Hydroelectric plant at the dam with a capacity of 3 MW. The dam is owned by the
United States Bureau Of Reclamation . It was built to reduce flows into the reclaimed wetlands of
Tule Lake . It also reduces flows into Tule Lake Sumps in the
Tule Lake National Wildlife Refuge . The reservoir created by the dam has a very large surface area, 25,760 acres (104.2 km&
2), 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, 74,500 acre feet (92,000,000 m³) of water from the reservoir evaporated, more than any other lake in the state besides
Shasta Lake , which has over 8 times the volume. Because of this, Clear Lake Reservoir is not an efficient water storage reservoir. This is a problem since the dam now provides water for
Irrigation of the eastern half of the
Klamath Basin . The reservoir is in
Modoc National Forest and
Clear Lake National Wildlife Refuge , so recreation opportunities are limited.
