Mono Lake reaches lowest level in 20 years

For over seventy years, Los Angeles has siphoned tributaries of the Eastern Sierra’s iconic Mono Lake, and for the past twenty their allotment has been restricted by a State Water Board decision that has kept water flowing to the city until historic drought conditions put that privilege on hold.

California’s four-year dry spell has lowered the levels of Mono Lake to an almost unprecedented level. In 1994, a landmark decision by the California State Water Board limited how much the Los Angeles Department of Water and Power (LADWP) could draw from Mono Lake’s tributaries after a protracted battle between the city and environmentalists. Twelve years before this decision was reached, in 1982, Mono Lake had dipped to 6,372 feet, said Geoff McQuilkin, Executive Director of the Mono Lake Committee. The most alarming affect of the drop was the exposure in 1979 of of a land bridge from the mainland to Negit Island.

Negit Island is home to the second-largest California Gull colony in North America (the Great Salt Lake is the largest), and when hungry coyotes exploited the land bridge to Negit, California Gulls abandoned the island in droves in favor of smaller protected islets. Only in 1999, when lake levels began once more to rise, did gulls begin to recolonize the largest island.

The 1994 decision was spurred in great part by the exposure of the land bridge, and pitted a newly-formed Mono Lake Committee against the LADWP. In the intervening years, the level of Mono Lake has slowly risen back toward the Water Board’s goal of a “management level” of 6,392 feet, said McQuilkin, but is still 14 feet shy. Progress toward the management level goal has been stymied by California’s prolonged drought.

“We’ve seen the lake go down more than 5 feet now over the last four years,” said McQuilkin. “The good news is if we hadn’t won that protection for Mono Lake back in 1994, it wouldn’t have gone up to the point that it was survivable. It would pretty much be ‘game over’ for the ecosystem of Mono Lake.”

The 1994 decision decreed a threshold of 6,377 feet—any lower, and Los Angeles would be forced to stop diverting any water from Mono Lake’s tributaries. The lake’s current level of 6378.2 feet, according to McQuilkin, is pushing uncomfortably close to the state-mandated threshold, leaving L.A. facing a water export of zero if this year’s winter does not materialize. The city has not faced this situation since the rules were imposed.

“If El Niño goes bust and we have a dry winter similar to the recent drought years, Mono Lake could lose maybe another two feet next year,” said McQuilkin.

Lake levels are measured on April 1 of each year, said LADWP spokeswoman Amanda Parsons, and Los Angeles’ exports for the 2016-17 year will be based on the lake’s water level at that time. “If the lake level is below 6377 [feet] on April 1, 2016 then Los Angeles will not export from the Mono Basin,” she said.

“All of the rules about how L.A. gathers and exports water are designed to get the lake to that level,” said McQuilkin. “You need the wet winters as well, but its all built around maintaining the lake there.”

Before Los Angeles built its aqueduct, according to McQuilkin, Mono Lake sat about 25 feet higher than it does today. The lake’s recognizable “tufas,” formed by underwater mineral springs, were exposed because of this drawdown. They are now a visitor attraction that bring tourists to the shores of the lake. “We’re not going back to where it was,” said McQuilkin, but “there’s sort of these safeguards that are built in so if the lake is falling…you kind of share the pain between L.A. water exports and the lake level.”

If the lake does not drop below the crucial threshold this coming April, L.A. will export 4,500 acre-feet of water from the Mono Basin—the maximum allotted by the Water Board when lake levels are under 6,380 feet. An acre-foot of water is approximately 326,000 gallons, according to the Mono Lake Committee. This is about enough water to meet the needs of ten people in Los Angeles for one year, based on recent data. “However, if the lake elevation on April 1 is at or above 6380, exports will be 16,000 acre-feet,” Parsons said.

Though the relationship between the LADWP and the Eastern Sierra’s residents and conservationists has often been contentious, the Water Board’s decision has left no room to bicker over this increasingly precious resource.

“This is all written in that 1994 decision,” said McQuilkin. “There’s no surprises, there’s no attorneys arguing for one side of the other, this has been written down for the past 20 years.”