In 1994, the state stepped in. That year, it adopted Decision 1631, setting streamflow requirements, water export limits, and other conditions to protect the lake’s public trust resources, according to the California State Water Resources Control Board . Every big city gets its water from somewhere, and those choices can reshape distant places. Mono Lake in eastern California is a good example. For decades, the city of Los Angeles took water from the streams that fed it.
The board explains that it had granted permits to Los Angeles and its Department of Water and Power to divert water from streams that flow into Mono Lake. This ended up causing significant harm to the lake’s environment and public trust resources. The diversions caused the lake level to drop 45 feet between 1941 and 1982. In 1994, the board amended the department’s water rights licenses to include streamflow requirements, limits on exports, and conditions to protect those resources.
Its authors add that, with few exceptions, the present condition of the Great Basin’s terminal lakes is the result of a long history of policy choices that did not consider the effects on the lakes themselves. Terminal lakes in the Great Basin support millions of waterbirds annually, the review notes. The authors link that long history of research to the legal water rules for Mono Lake.
A 2025 review in the journal BioScience , written by a team of U.S. Geological Survey scientists, found that Mono Lake has never met its management goal since 1994 and remains well below the target level. More than 99 percent of North America’s eared grebes depend on the brine shrimp and alkali flies those lakes produce in the fall, it adds. Mono Lake was the second most-studied lake in the review, with 21% of the publications, after Great Salt Lake at 39%.
Mono Lake is a terminal lake, which means it has no outlet to any other body of water.
Drought, climate change, and ongoing diversions have limited its recovery, and the lake remains below the long-term level, the board says.
What comes next
In October 2021, the board issued an order with new requirements to restore about 20 miles of creek and fish habitat in streams that flow into the lake. Board staff held public workshops in June 2026 to gather information on the condition of the lake and to discuss management options. The rules created a clear path for the lake in 1994, but recovery has taken longer than the board expected.
The board also hired UCLA’s Center for Climate Science to develop a water budget model to study how climate change and diversions affect lake levels.
