Pyramid Lake (Nevada)

Pyramid Lake
Pyramid Lake
Location	Washoe County, Nevada
Coordinates	40°0′N 119°30′W / 40.000°N 119.500°W
Type	endorheic, saline
Primary inflows	Truckee River
Primary outflows	evaporation
Catchment area	4,730 km²
Basin countries	USA
Max. length	48 km
Max. width	14 km
Surface area	487 km²
Max. depth	108.5 m
Water volume	29.2 km³
Shore length1	160 km
Surface elevation	1,155 m
Islands	Anaho Island
	1 Shore length is not a well-defined measure.

Pyramid Lake is an endorheic salt lake, approximately 188 square miles (487 km²) in area, in the Great Basin in the northwestern part of the U.S. state of Nevada. 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 / 40.000°N 119.500°W / 40.000; -119.500) with a surface elevation of about 3,790 feet (1155 m).

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 sea water. 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. Pyramid Lake was the deepest point in Lake Lahontan, reaching estimated 890 feet due to its low elevation level relative to the surrounding basins. In the 19th century the vicinity of the lake was inhabited by the Paiute.^{[citation needed]} The lake is now completely within the Pyramid Lake Indian Reservation. It was first mapped in 1844 by John C. Frémont, the American discoverer of the lake.^{[citation needed]}

Major fish species include the cui-ui lakesucker, which is endemic to Pyramid Lake, and Lahontan cutthroat trout (the world's record trout was caught in Pyramid Lake). The former is endangered, and the latter is threatened. Both species were of critical importance to the Paiute people in pre-contact times.^{[citation needed]} 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. Due to the construction of Derby Dam in 1903 made to divert water to croplands in Fallon, an adjacent town, The Pyramid Cutthroat Trout (the "salmon-trout" as described by Frémont) became extinct due to the immediate lowered water level, increased water salinity, and lack of fish-ladders on the dam (for upstream spawning runs), and were replaced with Lahontan cutthroat trout from hatcheries. Fish populations are now 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.^{[citation needed]}

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 ^[1]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.

Pyramid Lake is virtually a character in the classic novel of the Great Basin, City of Trembling Leaves, by Walter Van Tilburg Clark. The region was also rendered beautifully in the semi-abstract landscapes of Robert Caples, Clark's friend and the model for the characer Lawrence Black in the novel.

References

^ 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)

Water quality

References

See also