Pyramid Lake

• Category: Inland Aquatic Biomes.
• Geographic Location: North America.
• Summary: Named for its striking tufa limestone formations, Pyramid Lake is home to fairly healthy waters and a limited but rich biota.

The ice age that took place over 20,000 years ago in present-day Nevada was known as the Great Basin Ice Age. Unlike other ice ages, which are known for ice sheets and glaciers, this one was more marked by periods of increased rain and reduced evaporation. This large flow of water drained into the lower basin of the region, creating two vast lakes, Lake Lahontan and Lake Bonneville. During this time, the climate was much cooler and wetter than it is in present day Nevada, which is warm and arid.

Lake Lahontan had a depth of some 500 feet (152 meters) and stretched over 8,000 square miles (21,000 square kilometers), covering much of what is now Nevada. A warming and drying period followed, eventually shrinking and splitting the lake into smaller basins separated by mountain ranges. As one of the last remnants of ancient Lake Lahontan, today’s Pyramid Lake first took shape by about 9,000 BCE. Today, as one of the oldest and largest natural lakes in North America, the lake is fed by the Truckee River in the Sierra Nevada Mountains. About 15 miles (24 kilometers) long north to south, and up to 11 miles (18 kilometers) wide, Pyramid Lake reaches a depth of 350 feet (107 meters).

Pyramid Lake takes its name from the limestone deposits known as tufa, which here have formed in some very large pyramid-like shapes; they are found everywhere from deposits on the lake bottom to freestanding structures within and around the lake. The most singular tufa conglomeration is Anaho Island, which itself has the appearance of a weathered pyramid.

Flora and Fauna

The cyanobacterium Nodularia spumigena, a blue-green algae, is a fundamental part of the food web of Pyramid Lake. Late summer here finds large blooms occurring, which help to spread nitrogen into lake waters, a valuable part of the nutrient load for higher species.

Marshes, mainly around the mouth of the Truckee River inflow, and semiarid shrubland elsewhere around the lake combine to provide habitat where a great variety of vegetation flourishes. Buckwheat, bunchgrass, wheatgrass, elderberry, larkspur, juniper, sumac, and a range of herbs and forbs thrive.

Among aquatic species in the lake, the cui-ui (Chasmistes cujus) is perhaps most emblematic. This member of family Catostomidae, or sucker fish, is now listed as endangered. As one of only three species in genus Chasmistes, the cui-ui is known to occur only in the lower Truckee River and in Pyramid Lake. Feeding on zooplankton, the cui-ui of Pyramid Lake is a long-lived species, with a lifespan estimated at up to 40–50 years.

The cui-ui, along with Lahontan cutthroat trout (Oncorhynchus clarkii henshawi), were the favored species of indigenous peoples here in ancient times. Both types of fish were part of sacred ceremonies. One tribe, the Kuyuidokado, even took its name, meaning cui-ui eaters, from this valuable fauna.

One of the largest colonies of American white pelican (Pelecanus erythrorhynchos)—which favors a diet of cui-ui, Lahontan cutthroat trout, and tui chub—is based on Anaho Island here. They are known also to range out to 100 miles (160 kilometers) to search wetland areas for other preferred fish. Other birds in the Pyramid Lake biome include snowy egrets, great blue herons, terns, gulls, and cormorants. The lake also boasts several different waterfowl during certain seasons, including four species of loons and six species of grebes. In the fall bird, watchers see scoters and jaegers, and the summer brings black-throated sagebrush and Brewer’s sparrows to the sagebrush habitat surrounding the lake.

The native biota of the lake has been impacted by the spread of invasive freshwater mussels, the quagga (Dreissena rostriformis bugensis) and zebra (D. polymorpha). Their most pernicious effects include removing suspended particulate matter from the lake water, which permits deeper penetration of sunlight and resultant alteration of the natural balance of the lake’s species; another damaging effect is the excretion of material that depletes oxygen in the water.

Threats and Conservation

Dams and water-diversion projects on the Truckee River have caused tremendous harm to many of the native species of Pyramid Lake. Several of the hallmark fish species, for example, were blocked from their natural spawning runs to smaller streams off the Truckee; whole years thus went by without a reproductive class of cui-ui or cutthroat trout. Some mitigation and recovery efforts, including hatchery, restocking activity, and construction of the Pyramid Lake Fishway and Marble Bluff Fish Handling Facility, have managed to preserve at least the cui-ui in Pyramid Lake, albeit in an endangered status for the present. Still, the permanent loss of access to various favorable habitats, the eradication of some riverine vegetation from the area, and the introduction of invasive species have combined to permanently alter the biota of the Pyramid Lake ecosystem.

Global warming is thought to already be exacting a toll on this biome. Cui-ui fish are particularly sensitive to water temperature, for instance. Research indicates that their larvae are most successful at surviving when water temperature is in the range of 48–59 degrees F (9-15 degrees C), and are at great risk with temperatures in the range of 64–75 degrees F (18–24 degrees C). Spawning by cui-ui is timed to coincide with peak snowmelt, when chilled waters rush downstream from the Sierra Nevada range.

Unfortunately, the incidence of lower snow levels and earlier onset of the melt season have combined to apply stress to the cui-ui spawning survival rate in the Pyramid Lake area. Scientific modeling projects more winter precipitation will come in the form of rain instead of snow in coming years, a trend already underway.

Water pollution from urban runoff, agricultural flows, and septic tanks have caused the most persistent recent problems with the waters of the Truckee River that flows down into Pyramid Lake. Nevertheless, the water is considered in fairly strong condition. It is a priority for the people of the Paiute Pyramid Lake Reservation to help recovery of the fish species and the natural water quality of Pyramid Lake. Various agencies, such as the Resource Department of Pyramid Lake Fisheries, regularly sample water quality and monitor the health of the local fish in the area.

The Paiute Reservation covers over 700 square miles (1,813 square kilometers), including about 112,000 acres (45,400 hectares) of Pyramid Lake. Since the local governing body of the Paiute Reservation maintains official relations with both state and federal agencies, the Paiute are able to direct funds and support toward sustaining the health of the Pyramid Lake ecosystem. Much of the economy of the reservation relies on the fishing and leisure activities of tourists, such as hiking, camping, and kayaking. Some of the grants they receive have been used to help restore Pyramid Lake’s natural habitat, which ties into various aspects of the tribal people’s traditional ways. In 2021, the Paiute received $8.3 million in funding from the massive infrastructure package passed by Congress. The funds were granted to fund the Numana Dam Fish Project, which will modify the dam to allow the passage of fish, in particular the Lahontan cutthroat. The funding was a major victory for the Paiute, who have wanted to modify the dam for the past 20 years.

In 2010, First Lady Michelle Obama selected Pyramid Lake as the first Preserve America Tribal Community in Nevada. This is part of a national initiative that supports community work aimed at preserving both cultural and natural heritage factors in a chosen area. Such an initiative adds momentum to the range of independent and government-sponsored scientific investigations and recovery initiatives that are generally thought to be improving the ecology, sustainability, and water quality of Pyramid Lake.

Bibliography

Benson, Larry. “The Tufas of Pyramid Lake.” United States Geological Survey, .

Faulk, Natalie. "The Sinister Story behind This Popular Nevada Lake Will Give You Chills." Nevada, 3 Mar. 2021, www.onlyinyourstate.com/nevada/sinister-story-popular-nevada-lake-chills/. Accessed 29 Sep. 2024.

Knack, Martha C. “A Short Resource History of Pyramid Lake, Nevada.” Ethnohistory, vol. 24, no. 1, winter 1977.

Lebo, M. E. and P. Wagner. “Managing the Resources of Pyramid Lake, Nevada, amidst Competing Interests.” Journal of Soil and Water Conservation, vol. 51, no. 2, 1996.

Nevada Department of Conservation & Natural Resources. “Nevada’s Native Fishes.” .

"Numana Dam Fish Passage Project." U.S. Fish and Wildlife Service, 16 May 2023, www.fws.gov/project/numana-dam-fish-passage-project. Accessed 29 Sep. 2024.

Roedel, Kaleb. "Nevada Tribe Tries to Recover Native Fish Amid Impacts of Dams, Climate Change." KUNR Public Radio, 16 June 2022, www.kunr.org/energy-and-environment/2022-06-16/nevada-tribe-recover-native-fish-impacts-dams-climate-change. Accessed 29 Sep. 2024.

White, Oliver. "The Future of Pyramid Lake's Lahontan Cutthroats." Fly Fisherman, 5 Oct. 2021, www.flyfisherman.com/editorial/pyramid-lakes-lahontan-cutthroats/452586. Accessed 29 Sep. 2024.