| Pyramid Lake (Nevada) | |
| Lake | |
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Pyramid Lake is east of the Virginia Mountains
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| Name origin: pyramidal limestone columns | |
| Country | United States |
|---|---|
| State | Nevada |
| District | Washoe |
| Elevation | 3,796 ft (1,157 m) [1] |
| Coordinates | |
| Length | 29.8 mi (48 km) |
| Width | 8.7 mi (14 km) |
| Area | 188 sq mi (487 km2) |
| GNIS ID | 856349 [1] |
| Volume | 23,660,000 acre feet (29.18 km3) |
| Reference #: | 18[2] |
Pyramid Lake is the geographic sink of the Truckee River Basin and is located 40 mi (64 km) northeast of Reno. The inflow is moderately high silt-loaded surface runoff.
Pyramid Lake is fed by the Truckee River after leaving Lake Tahoe upstream and enters the lake from its southern end. There is 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 1/6 that 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.
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A remnant of the Pleistocene Lake Lahontan (~890 feet deep), the lake area was inhabited by the 19th century Paiute, which used the Tui chub and Lahontan cutthroat trout from the lake[3] (the former is now endangered and the latter is threatened). The lake was first mapped in 1844 by John C. Frémont, the American discoverer of the lake who also gave it its English title.[4]
In the 19th century two battles were fought near the lake, a marker was placed in the 1960s commemorating these battles.[7] As a result of water diversion from 1905 onwards by Derby Dam, the lake's existence was threatened. As a result, the Paiute sued the Department of the Interior. By the mid 1970s, the lake had lost 80 feet of depth, and according to Paiute fisheries officials, the life of the lake was seriously under threat. The beneficiary of the water diversion in the 1970s was a racially exclusive sportsman's and leisure reserve used for white hunting and recreation near the town of Fallon. In the opinion of John Pilger, the irrigation scheme for which water was diverted was an economic failure.[8]
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 an estimated 890 feet (270 m) 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.[3] 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 who also gave it its English title.[4]
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.[9]
Pyramid Lake was used as the filming location of Sea of Galilee in the 1965 film, The Greatest Story Ever Told.[10]
Major fish species include the cui-ui lakesucker, which is endemic to Pyramid Lake, the Tui chub and Lahontan cutthroat trout (the world record cutthroat 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.[3] 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 Lahontan cutthroat trout (the "salmon-trout" as described by Frémont) became extinct in Pyramid Lake and its tributaries 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.
Because of the endangered species present and because 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[6] to analyze impacts of a variety of land use and wastewater management decisions throughout the 3,120-square-mile (8,100 km2) 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.