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The Upside to Cutting Water to L.A. From Mono Lake

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Rainstorm over Mono Lake, 2007 | Photo: Chris Clarke

Since it's Friday afternoon, here's some good news for the weekend: a sustained, decades-long campaign of activism to save Mono Lake has really, officially saved the lake. The lake's level was at 6,379 feet above sea level when it was measured April 1, 20 inches lower than it was this time last year.

That's because the ongoing drought has shrunk the Sierra Nevada snowpack that is Mono Lake's sole source of new water. And since the lake is below 6,380 feet, according to a 1994 agreement with the State Water Resources Control Board, the Los Angeles Department of Water and Power must cut the amount of water it diverts from Mono Lake's feeder streams by 70 percent.

That agreement, reached after decades of campaigning and litigation by environmental groups, reduced LADWP's diversions significantly even in wetter years. If that hadn't happened the lake's level would be 29 feet lower now after four years of drought, which would have killed off Mono Lake's unique ecosystem.

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That's according to Geoffrey McQuilkin, Executive Director of the Mono Lake Committee, who reported on the new lake level measurement on the Committee's website this week.

Mono Lake, a cause celebre in California environmental protection circles since the 1970s, is one of North America's oldest lakes. Occupying the bottom of a landlocked basin with no outflow, the lake accumulates all the dissolved minerals it receives from the fresh water that flows into it from streams such as Rush, Mill, and Lee Vining creeks, which drain melting snow and rain in the neighboring Yosemite high country.

All those dissolved minerals mean that the lake is quite alkaline, with a pH of about 10, and that it's currently about three times as salty as the ocean. That's way too salty for fish, but Mono Lake is anything but barren. A thriving population of photosynthesizing algae in the lake supports hefty crops of brine shrimp and alkali flies, which themselves feed nearly incomprehensible numbers of migrating birds, which stop by each year in the millions.

The flies and shrimp also feed year-round residents: the lake is home to the second-largest population of California gulls in the world (the Great Salt Lake is first), and a wide range of other wildlife calls the lake its home.

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California gull chases alkali flies (the black stuff) on the Mono Lake south shore, 2005 | Photo: Chris Clarke
 

That would have made the water far too saline to support the algae and the small critters who eat the algae, which means the lake would have become essentially useless as stopover habitat for all those migrating birds.

Thanks to the agreement reached in September 1994, in which the State Water Quality Control Board tied the amount of water LADWP can siphon from the Mono Basin to the lake's levels, that didn't happen. Since 1941, LADWP had been taking around 30,000 acre-feet from the lake's feeder streams each year. In that year, the lake's level was around 6,417 feet above sea level. By 1980, Mono's surface had dropped 45 feet, endangering the lake's living organisms and exposing a large amount of alkaline lakebed.

A series of restraining orders and court injunctions starting in 1984 cut back the amount LADWP could take out of the local creeks, and the 1994 agreement with the Water Resources Board formalized those restrictions. In wet years, LADWP can export 16,000 acre-feet per year from the Mono Basin. When lake levels drop to 6,380 feet, as happened sometime in the last year, L.A.'s take gets cut to 4,500 acre-feet a year.

If the lake drops by two more feet, to 6,377 feet above sea level, then LADWP's share of the water from the lake's feeder streams gets cut to nothing. Both the lake's defenders and LADWP are hoping that doesn't happen, and the Mono Lake Committee's Greg Reis writes that a wet snowstorm expected in the area this weekend may offer some help.

Everything depends on forces that are almost entirely out of our control at this point: if the drought continues for another year and water levels drop to 6,375 feet above sea level, that will re-expose a land-bridge between the lake shore and Negit Island, which the local California gulls use as a rookery. That land bridge has been submerged since 1994, but its exposure in the 1970s and the 1990s allowed predators to walk to the island and eat gull eggs, wreaking havoc on the gull populations.

It remains to be seen whether that will happen. In the meantime, though, it's worthwhile to remember that as bad as this drought is, if it hadn't been for a few determined individuals campaigning to save Mono Lake during the 1970s and 1980s, things would be a whole lot worse for the lake than they are now. That's worth keeping in mind when you start to feel like the world's problems are too big to face head-on.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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