page_title: Lake Tahoe
section_title: Ecology
hierarchical_section_title: Lake Tahoe / Natural history / Ecology
caption_attribution_description: English: Beaver dam on Blackwood Creek, tributary to Lake Tahoe's western shore - dam broken by apparent human interference.
context_page_description: Lake Tahoe is a large freshwater lake in the Sierra Nevada mountain range of the United States. Lying at 6,225 ft, it straddles the state line between California and Nevada, west of Carson City. Lake Tahoe is the largest alpine lake in North America, and at 122,160,280 acre⋅ft trails only the five Great Lakes as the largest by volume in the United States. Its depth is 1,645 ft, making it the second deepest in the United States after Crater Lake in Oregon.
  The lake was formed about two million years ago as part of the Lake Tahoe Basin, with the modern extent being shaped during the ice ages. It is known for the clarity of its water and the panorama of surrounding mountains on all sides. The area surrounding the lake is also referred to as Lake Tahoe, or simply Tahoe. More than 75% of the lake's watershed is national forest land, being the Lake Tahoe Basin Management Unit of the United States Forest Service.
  Lake Tahoe is a major tourist attraction in both Nevada and California. It is home to winter sports, summer outdoor recreation, and scenery enjoyed throughout the year. Snow and ski resorts are a significant part of the area's economy and reputation.
context_section_description: Vegetation in the basin is dominated by a mixed conifer forest of Jeffrey pine (Pinus jeffreyi), lodgepole pine (P. contorta), white fir (Abies concolor), and red fir (A. magnifica). The basin also contains significant areas of wet meadows and riparian areas, dry meadows, brush fields (with Arctostaphylos and Ceanothus) and rock outcrop areas, especially at higher elevations. Ceanothus is capable of fixing nitrogen, but mountain alder (Alnus tenuifolia), which grows along many of the basin's streams, springs and seeps, fixes far greater quantities, and contributes measurably to nitrate-N concentrations in some small streams. The beaches of Lake Tahoe are the only known habitat for the rare Lake Tahoe yellowcress (Rorippa subumbellata), a plant which grows in the wet sand between low- and high-water marks. Vegetation in the lake itself formerly consisted of native Chara and Gomphoneis algae and coontail (Ceratophyllum demersum), but the later introduction of curlyleaf pondweed (Potamogeton crispus), Eurasian watermilfoil (Myriophyllum spicatum), and Zygnema and Cladophora algae has transformed the nearshore environment.
  Native fish of the lake include Lahontan cutthroat trout (Oncorhynchus clarki henshawi), mountain whitefish (Prosopiurm williamsoni), Lahontan speckled dace (Rhinichthys osculus robustus), Lahontan redside (Rhinichthys egregious), Lahontan Lake tui chub (Siphateles bicolor pectinifer), Tahoe sucker (Catostomus tahoensis), Lahontan mountain sucker (Catostomus platyrhynchus lahontan), and Paiute sculpin (Cottus beldingi). Most of these fish populations have been significantly reduced due to the introduction of nonnative fish, Asian clam (Corbicula fluminea), and mysid shrimp. Competition from introduced fish led cutthroat trout to be completely extirpated from the lake in the early 20th century until reintroduction efforts started in 2019.
  Introduced fish species include lake trout (Salvelinus namaycush), rainbow trout (Oncorhynchus mykiss gairdneri), sockeye salmon (Oncorhyncus nerka), brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), common carp (Cyprinus carpio), golden shiner (Notemigonus crysoleucas), western mosquitofish (Gambusia affinis), bluegill (Lepomis macrochirus), black (Pomoxis nigromaculatus) and white (P. annularis) crappie, largemouth (Micropterus salmoides) and smallmouth (Micropterus dolomieu) bass, and brown bullhead (Ameiurus nebulosus). Each autumn, from late September through mid-October, mature sockeye salmon transform from silver-blue color to a fiery vermilion, and run up Taylor Creek, near South Lake Tahoe. As spawning season approaches the fish acquire a humpback and protuberant jaw. After spawning they die and their carcasses provide a feast for gatherings of mink (Neovison vison), bears (Ursus americanus), and bald eagles (Haliaeetus leucocephalus). The non-native salmon were transplanted from the North Pacific to Lake Tahoe in 1944.
  North American beaver (Castor canadensis) were re-introduced to the Tahoe Basin by the California Department of Fish and Wildlife and the U.S. Forest Service between 1934 and 1949. Descended from no more than nine individuals, 1987 beaver populations on the upper and lower Truckee River had reached a density of 0.72 colonies (3.5 beavers) per kilometer. At the present time beaver have been seen in Tahoe Keys, Taylor Creek, Meeks Creek at Meeks Bay on the western shore, and Kings Beach on the north shore, so the descendants of the original nine beavers have apparently migrated around most of Lake Tahoe. Recently novel physical evidence has demonstrated that beaver were native to the Sierra until at least the mid-nineteenth century, via radiocarbon dating of buried beaver dam wood uncovered by deep channel incision in the Feather River watershed. That report was supported by a summary of indirect evidence of beaver including reliable observer accounts of beaver in multiple watersheds from the northern to the southern Sierra Nevada, including its eastern slope. A specific documented record of beaver living historically in Lake Tahoe's N
caption: Damaged beaver dam on Blackwood Creek. Beaver dams are easily crossed by trout and their ponds may serve as critical breaks for wildfires.[29][30]
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