Dating lake levels
Lewisville Lake is the second lake to impound the waters of the Elm Fork of the Trinity River in this area. The dam was 10,890 feet (3,320 m) long with a 567-foot (173 m) long service spillway.
Lake Mendocino is a key drinking water source for the cities of Ukiah, Healdsburg, Cloverdale and Hopland, and also provides water to the Water Agency’s Russian River water supply system.Pass-through water is water flowing into the reservoir that is not stored in, but passes through, the reservoir.Project water releases to supplement the natural flows in the Russian River and Dry Creek are necessary to meet mandatory minimum streamflow requirements that exist for both of these watercourses.The Target Storage Curve represents the normal daily storage level for each day of the year.The daily storage levels were determined based on reservoir modeling of an average year under “Normal” water supply conditions as designated by the Russian River System hydrologic index.If it is not achieved by 2020, the Water Board will hold a hearing to consider the condition of Mono Lake and determine if further license revisions are appropriate.
Once the 6391' target is achieved, the water export rules change in order to maintain a long-term average lake elevation—or "management level"—of 6392'.
Categories of water supply conditions are based on criteria defined in the State Water Resources Control Board Decision 1610.
These conditions establish the applicable instream flow requirements.
Water releases from Lake Mendocino support flows in the Russian River for the threatened Chinook salmon and steelhead trout during the fall and winter seasons.
Lake Sonoma is about four times larger than Lake Mendocino and can provide multiple years of water supply.
It is anticipated that this level will maintain a healthy lake ecosystem and provide protection for the basin's resources such as the quality of the air.