In order to provide water for growing Los Angeles, water was diverted from the Owens River and then from the tributaries that fed Mono Lake (see California Water Wars). In 1941 the city of Los Angeles extended an aqueduct system into the Mono Basin, diverting water that would otherwise have entered Mono Lake.

Enough water was diverted that evaporation soon exceeded inflow and the lake level fell rapidly, exposing alkaline sands and once-submerged tufa towers, and turning Negit Island into a peninsula, exposing the nests of gulls to coyotes and forcing them to abandon the island.

In 1976 University of California, Davis graduate student David Gaines earned his master's degree studying the Mono Lake ecosystem and was instrumental in alerting the public of the effects of the lower water level. Gaines formed the Mono Lake Committee in 1978 and joined up with the Audubon Society to fight a now famous court battle to protect Mono Lake through state public trust laws. Despite these efforts, the lake is still lower than historic levels and exposed shorelines are a source of significant alkali dust during periods of high winds.



Owens Lake, which sustained a similar ecosystem, completely dried up because of water diversions. Mono Lake was spared the same fate on September 28, 1994, when the California State Water Resources Control Board issued an order to protect Mono Lake and its tributary streams. Since that time the lake level has steadily risen; in 1941 the lake level was at 6417 feet above sea level and as of 2004 it was at 6381 feet (1945 m)•. The goal is to have lake level rise to 6392 feet above sea level, a goal made more difficult by drought in the American West.



The lake contains approximately 280 million tons of dissolved salts, with the salinity varying on the amount of water in the lake at any given time. Before 1941, the salinity was approximately 50 grams per liter (g/l) (compared to a value of 31.5 g/l for the world's oceans). In 1982, when the lake reached its lowest level, the salinity had nearly doubled to 99 g/l. In 2002 it was measured at 78 g/l and is expected to stablize at an average 69 g/l as the lake replenishes over the next 20 years.

The hypersalinity and high alkalinity (pH=10 or equivalent to 2.5 grams of NaOH per liter of water•) of the lake, means that no fish are native to the lake. An attempt by the California Department of Fish and Game to stock the lake failed. The lake is famous for the Mono Lake brine shrimp, Artemia monica, a tiny species of brine shrimp, no bigger than a thumbnail, that are found nowhere else on earth. During the warmer summer months, an estimated 4-6 trillion brine shrimp inhabit the lake. The species has no food value for humans, but is a staple for birds of the region. Also an important food source, alkali flies ("Ephydra hians") live along the shores of the lake and walk underwater encased in small air bubbles to graze and to lay eggs. The whole food chain of the lake is based on the high population of single-celled algae present in the warm shallow waters.


Mono Lake is a vital resting and eating stop for migratory shorebirds and has been recognized as an International Reserve in the Western Hemisphere Reserve Network. Nearly 2,000,000 waterbirds, including 35 species of shorebirds, use Mono Lake to rest and eat for at least part of the year. Some shorebirds that depend on the resources of Mono Lake include American avocets, Killdeers, and sandpipers. Over 1.5 million eared grebes and phalaropes use Mono Lake during their long migrations.

Late every summer tens of thousands of Wilson's phalaropes and red-necked phalaropes arrive from their nesting grounds, and feed until they continue their migration to South America or the tropical oceans respectively.

In addition to migratory birds, a few species spend several months to nest at Mono Lake. Over 85% of the state population of California gulls nest at Mono Lake each year. After abandoning the landbridged Negit Island in the late 70s, California gulls have moved to some nearby islets and have established new, if less protected nesting sites. Cornell University and Point Reyes Bird Observatory have continued the study of nesting populations on Mono Lake that was begun over 20 years ago. Snowy Plovers also arrive at Mono Lake each spring to nest along the remote eastern shores.

In Mark Twain's Roughing It (1872), chapter 38 and chapter 39 provide a humorous but informative early description of Mono Lake in its natural condition in the 1860's.