Mono Lake levels continue to drop

Mono Lake after a clearing storm.

Twenty-seven years after the California State Water Board’s decision to protect Mono Lake by limiting Los Angeles’ water diversions, a combination of environmental changes such as drought and heat, along with water diversion changes have left the lake 11 feet below the state’s established management level target which is less than halfway to the projected lake level goal.

This summer’s projected continuing drought and the extremely low snowpack from the past winter will not help, with the lake already at 1.5 feet lower than last year, Mono Lake experts said this week.

“We’re... at the edge of a lot of really troublesome, worrisome situations for the lake and its ecosystem and recreation,” said Geoff McQuilkin, executive director of the Mono Lake Committee, an environmental nonprofit dedicated to restoring and protecting the lake.

Mono Lake currently sits 6,380.9 feet above sea level, which is 1.5 feet lower than last year. In large part due to last year’s watershed runoff of only 49 percent of average, and the predictions for this year’s to fall around 58 percent of average, the lake is predicted to fall below 6,380 next year.

The implications of this drop are frightening, according to McQuilkin. “We know that Mono Lake is at risk when the lake is low,” said McQuilkin. “When you’re in a drought, on top of being in the era of climate change, all the risks of the past are still risks, like the land bridge being exposed, giving predators access to a nesting colony of gulls.” 

Another implication of the low lake level on local conditions, said Mareen McGlinchy Hydrology Modeling Specialist at the Mono Lake Committee, is the worsening of air quality. “Since the lake is lower, more of the lakebed is exposed, and with wind events… we have Clean Air Act violations,” she said. In addition, as the lake falls, its ecosystem comes closer and closer to danger, endangering the millions of migratory birds that depend upon it.

According to McGlinchy, a combination of factors can be attributed to the 11-foot difference between the Water Board’s expectations for the lake, and its current level. 

The main factors include a decrease in Sierra Nevada runoff and precipitation around the lake; possible increase in evaporation rates triggered possibly by higher temperatures; and the Los Angeles Department of Water and Power’s efforts and success in diverting the maximum amount of water allowed every year since the Water Board decision. 

When looked at alone, none of these factors are outstanding, but their impact becomes clear when added up over time, lake managers said. 

For example, a seemingly small (two percent) decrease in Sierra Nevada runoff over 26 years is actually the equivalent of around 85,000-acre feet of runoff, which translates to about two total feet of lake elevation, if that water had arrived in the lake as originally planned and forecast.

However, advocates for the lake have not given up hope. “There’s one part of the Mono Lake water balance that we Californians have control of, and that is the water diversions,” said McGlinchy. 

The Water Board will soon hold a hearing to reassess the guidelines for reaching management level, and lake researcher and those who love the lake hope a combination of science, collaboration, and love for the environment will assemble a new path toward saving Mono Lake.

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