Drought Shrinking Mono Lake: Water Exports To L.A. Near-Certain To Be Cut

Mono Lake, the picturesque Eastern Sierra alkaline lake whose odd tufa towers are known worldwide, is being seriously affected by the ongoing drought, according to environmentalists. The lake's water level has dropped to the point where any further decline will force the L.A. Department of Water and Power to reduce water exports from the Mono basin.

As a result of a 1994 directive by the State Water Quality Control Board, LADWP can divert up to 16,000 acre-feet from Mono Lake's streams per year as long as lake levels remain above 6,380 feet above sea level. If the lake drops below that level, LADWP can take no more than 4,500 acre-feet per year.

As of April 1, according to the Mono Lake Committee, the lake's level stood at 6,380 feet... and eight inches. If that eight-inch margin continues to dwindle during the next winter and spring, LADWP has to cut its water exports from the Mono Basin by more than two-thirds.

That requirement comes as a result of decades of campaigning and litigation to save the lake from the effects of water exports by LADWP.

With no outlet, water only leaves Mono Lake through evaporation, which means anything dissolved in the creekwater that flows into the lake stays in the lake. As a result, Mono's lakewater had a third more dissolved salts than the ocean even before 1941, when LADWP began to tap one of the lake's feeder streams, Rush Creek, to send water to Los Angeles.

In the decades after pumping began, lake levels dropped precipitously and salt concentrations rose. The lake was too salty for fish even before 1941, but by 1982 the lake's salinity was so high -- three times as salty as seawater -- that the lake's extremely salt-tolerant brine shrimp were in danger. Their loss would have deprived the lake's huge migratory shorebird population of a food source. About two million birds use Mono Lake as stopover habitat on their migrations, which makes its brine shrimp bounty a crucial resource for birds across the West.

Those birds were threatened by other aspects of the lake's decline as well. A California gull nesting colony on the lake's Negit Island, the second largest in the world, was exposed to predation when the receding waters revealed a land bridge to the island, allowing coyotes to walk over and chow down on eggs and nestlings.

In 1982, the lake reached its lowest level ever recorded: 6,372 feet. The year after, the California Supreme Court ruled that Mono Lake's ecosystem was protected by the state's Public Trust Doctrine, meaning that the state has an obligation to protect the lake as a resource belonging to the public. In 1994, the State Water Quality Control Board followed up on that ruling by establishing a target water level for the lake's long-term health -- 6,392 feet above sea level -- and strict limits on the amount of water LADWP could divert from the lake's tributaries at different lake levels.

That's the legal background for the requirement that LADWP reduce its pumping if the lake drops another eight inches from its April 1 level.

According to the Mono Lake Committee's education director Bartshé Miller, the lake is almost certain to drop below the threshold level of 6,380 feet and then some: "Since April 1, 2011, Mono Lake has receded three vertical feet. Unfortunately, the lake will continue to decline through this fall, and we can expect to lose another 1-1.5 feet of elevation."

Which means that LADWP's customers have even more reason to cut down on the water they use.