The death of Mono Lake (California, USA)

Mono Lake is a saline soda lake in Mono County (California, USA). The lack of an outlet causes high levels of salts to accumulate in the lake which make its water alkaline.

The city of Los Angeles diverted water from the freshwater streams flowing into the lake, lowering its lake level. But 2022 was already the third consecutive year of drought that shrunk the creeks that cascade down the eastern Sierra Nevada. The level of Mono Lake has fallen so low it has triggered a 72% reduction in the amount of water Los Angeles could divert from area streams.

On April 1, 2022, Mono Lake’s level measured just under 1,945 meters above sea level — about 2.5 centimeters below a threshold set in the licenses of Los Angeles Department of Water and Power (DWP) for diverting alpine runoff from streams that feed the lake east of Yosemite National Park.

The measurement, taken at the start of a new runoff year, triggered a requirement that the DWP reduce its annual water exports from 19,735,680 m³, which is enough to supply 192,000 residents, to 5,550,660 m³, just enough to serve 54,000 residents. Over the last runoff year from April through March, the DWP exported 17,022,024 m³ from Mono Basin, less than the permitted of 5,550,660 m³. That amount shrunk by two-thirds during the next 12 months.

The last time Mono Lake fell below the same threshold was from 2015 to 2017, in the final years of California’s last severe drought. Mono Lake’s level rebounded with wet weather in 2017, then declined over the last three extremely dry years.

The hypersaline high-desert lake, famous for its towering, craggy tufa formations, has been at the center of long-running disputes over the city’s diversions of water from the lake’s feeder streams. The State Water Resources Control Board established limits on diversions in 1994 to resolve a fight between environmentalists and Los Angeles.

But conservationists remain concerned about the environmental effects of decades of water diversions, especially given the current extreme drought and the worsening effects of global warming. The Mono Lake shoreline is continuing to retreat, creating a 'bathtub ring' of dusty lake bottom. Prepare for dust and salt storms in the near future.

Mono Lake's current level can be checked here.