Pyramid Lake

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This article is about Pyramid Lake in Nevada. For others, see Pyramid Lake (disambiguation)

Pyramid Lake is an endorheic saline lake, approximately 188 mi² (487 km²) in area, in the Great Basin in northwestern Nevada in the United States. One of the largest lakes in the United States, it is located in southern Washoe County 40 mi (64 km) northeast of Reno, along the east side of the Virginia Mountains ([40°0′N 119°30′W]) with a surface elevation of about 1155 m (3790 feet).

It is fed by the Truckee River (the outlet of Lake Tahoe), which enters the lake from its southern end. It has no outlet, with water leaving only by evaporation, or sub-surface seepage. The lake has about 10% of the area of the Great Salt Lake, but it has about 25% more volume. The salinity is approximately 1/6th of the ocean. Although clear Lake Tahoe forms headwaters that eventually drain to Pyramid Lake, The Truckee River delivers more turbid waters to Pyramid Lake after traversing the steep sierra terrain and collecting moderately high silt loaded surface runoff.

The lake is the largest remnant of ancient Lake Lahontan that covered much of northwestern Nevada at the end of the last ice age. In the 19th century the vicinity of the lake was inhabited by the Paiute. The lake is now completely within the Pyramid Lake Indian Reservation. It was first mapped in 1844 by John C. Fremont, the American discoverer of the lake.

Major fish species include the cui-ui lakesucker, which is endemic to Pyramid Lake, and Lahontan cutthroat trout. The former is endangered, and the latter is threatened. Both species were of critical importance to the Paiute people in pre-contact times. As they are both obligate freshwater spawners, they rely on sufficient inflow to allow them to run up the Truckee River to spawn otherwise their eggs will not hatch. Diversion of the Truckee for irrigation since the early 20th century has reduced inflow such that it is rarely sufficient for spawning in modern times. Fish populations are sustained by several tribally-run fish hatcheries.

The name of the lake comes from the impressive tufa formations nearby. The largest such formation, Anaho Island, is home to a large colony of American White Pelicans and is highly restricted for ecological reasons. Access to the Needles, another spectacular tufa formation at the northern end of the lake has also been restricted due to recent vandalism.

Water quality

Because of the endangered species present and due to the fact that the Lake Tahoe Basin comprises the headwaters of the Truckee River, Pyramid Lake has been the focus of several water quality investigations, the most detailed starting in the mid-1980s. Under direction of the U.S. Environmental Protection Agency, a comprehensive dynamic water quality computer model, the DSSAM Model was developed C.M.Hogan,Marc Papineau et al. Development of a dynamic water quality simulation model for the Truckee River, Earth Metrics Inc., Environmental Protection Agency Technology Series, Washington D.C. (1987)to analyze impacts of a variety of land use and wastewater management decisions throughout the 3120 square mile Truckee River Basin. Analytes addressed included nitrogen, reactive phosphate, total dissolved solids, dissolved oxygen and nine other parameters. Based upon use of the model, some decisions have been influenced to enhance Pyramid Lake water quality and aid the viability of Pyramid Lake biota.

References

See also

• Winnemucca Lake
• Carson Sink

 

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