Mono Lake

Mono Lake
Dicklyon · CC BY 4.0 · source
Name	Mono Lake
Caption	Tufa towers at Mono Lake
Location	Mono County, California
Coords	38, 01, 00, N...
Type	Endorheic, saline, soda lake
Inflow	Rush Creek, Lee Vining Creek, Mill Creek
Outflow	Evaporation
Basin countries	United States
Length	13 mi
Width	9.3 mi
Area	45,133 acre
Depth	57 ft
Max-depth	159 ft
Volume	2,970,000 acre.ft
Elevation	6,383 ft
Islands	Negit Island, Paoha Island
Cities	Lee Vining, California

Mono Lake is a large, ancient saline soda lake located east of the Sierra Nevada mountain range in Mono County, California. Formed over one million years ago as a terminal lake in the endorheic Mono Basin, it is known for its striking tufa towers and unique, highly alkaline ecosystem. The lake has been a focal point of significant environmental litigation and conservation efforts following drastic water diversions by the Los Angeles Department of Water and Power.

Geography and Climate

Situated within the Great Basin at an elevation of over 6,380 feet, the lake is bordered by the steep escarpment of the Sierra Nevada to the west and the arid hills of the Mono-Inyo Craters chain to the south. The primary inflows are streams such as Rush Creek, Lee Vining Creek, and Mill Creek, which originate from Sierra Nevada snowmelt. The climate is characterized by cold, snowy winters and dry summers, with the basin lying in the rain shadow of the Sierra Nevada, receiving less than ten inches of annual precipitation. Prominent features include the lake's two major islands, volcanic Negit Island and the larger, sediment-based Paoha Island.

Geology

The lake basin is a tectonic depression related to crustal extension in the Basin and Range Province. Its geological history is dominated by volcanism, evidenced by the nearby Mono-Inyo Craters and Panum Crater. The lake's most iconic features are its calcareous tufa towers, formed underwater from the interaction of freshwater springs rich in calcium with the carbonate-rich lake water. The region's volcanic past is also recorded in layers of volcanic ash, including the Mono Lake Excursion, a geomagnetic event documented in lake sediments. Underlying the basin are extensive deposits of borax, mined in the 19th century.

Ecology

The lake's hypersaline and alkaline waters, with a pH around 10, support a simplified but prolific food chain. The base is formed by microscopic algae and endemic, shrimp-like brine shrimp, which feed massive populations of migratory birds. The lake is a vital stopover on the Pacific Flyway for species like California gulls, Wilson's phalaropes, and eared grebes, which nest primarily on Negit Island. Terrestrial surroundings include sagebrush steppe habitat, while the freshwater streams support riparian zones critical for willow and aspen.

History

The Kutzadika'a band of the Northern Paiute have inhabited the Mono Basin for centuries, harvesting the brine shrimp for food. The lake was named by Californio explorer Diego de Borica, though it was first described for the American public by the Topographical Engineers during the Frémont expedition. In the late 19th century, the Mono Lake Railway and the town of Bodie supported mining booms for borax and gold. The most transformative event began in 1941 when the Los Angeles Department of Water and Power commenced diverting water from the lake's tributary streams to supply Los Angeles.

Conservation Efforts

Large-scale diversions caused the lake level to drop precipitously, exposing tufa towers, increasing salinity, and endangering the ecosystem by creating a land bridge to Negit Island, allowing predators access to gull nests. This prompted the formation of the Mono Lake Committee in 1978, which led a long legal battle. A landmark decision by the California State Water Resources Control Board in 1994, following litigation that reached the Supreme Court of California, mandated restoration flows to the lake. Ongoing management by the Los Angeles Department of Water and Power under this ruling aims to stabilize the lake level, with the area protected within the Mono Lake Tufa State Natural Reserve. Category:Lakes of California Category:Great Basin Category:Endorheic lakes of the United States