Assessment

* A Past View of Resources in the Lahontan Region

* Deer Creek Watershed Conservancy

* Watershed Risk Assessment

* Mercury Contamination

Strategies for Improving Watersheds and Aquatic Biodiversity

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Aquatic Habitats The aquatic/riparian systems are the most altered and impaired habitats of the Sierra.

Stream Flow Dams and diversions throughout most of the Sierra Nevada have profoundly altered stream-flow patterns (timing and amount of water) and water temperatures, with significant impacts to aquatic biodiversity.

Riparian Status Riparian areas have been damaged extensively by placer mining (northern and west-central Sierra) and grazing (Sierra-wide), and locally by dams, ditches, flumes, pipelines, roads, timber harvest, residential development, and recreational activities.

Sediment Excessive sediment yield into streams remains a widespread water-quality problem in the Sierra Nevada.

Water Quality Major water-quality impacts on the Sierra are (1) impairment of chemical water quality downstream of urban centers, mines, and intensive land-use zones, (2) accumulation of near toxic levels of mercury in many low-to middle-elevation reservoirs of the western Sierra, (3) widespread biological contamination by human pathogens (especially Giardia ), and (4) increased salinity in east-side lakes as a result of water diversions.

Introduced Aquatics Introduction of non-native fishes (primarily trout) has greatly altered aquatic ecosystems through impacts on native fish, amphibians, and invertebrate assemblages.

Amphibian Status Amphibian species at all elevations have severely declined throughout the Sierra Nevada.

Anadromous Fish Anadromous fish (chinook salmon, steelhead), once native to most major Sierran rivers north of the Kings River, are now nearly extinct from Sierran rivers.

Aquatic Invertebrates Local degradation of habitats has led to significant impacts on aquatic invertebrates, which make up the vast majority of aquatic species in the Sierra Nevada.