Like wild trout, California's native steelhead are subject to a multitude of threats. The three biggest factors are inadequate stream flows; blocked access to historic spawning and rearing waters by dams; and human activities that discharge sediment and debris into watercourses.

The map above presents National Marine Fisheries Service (NMFS) designation of steelhead listings throughout California by Evolutionarily Significant Units (ESU's).

A brief assessment of the health of steelhead in each of the State's six ESUs is presented below.

Klamath Mountain Province. ESU 7, Status: Listing Not Warranted.

Steelhead in this ESU were originally listed as Candidate status which means that NMFS did not consider them endangered or threatened, but warranted monitoring. A legal judgment required NMFS to re-evaluate their decision and on March 28, 2001 NMFS declared the ESU as Not Warranted for listing. This no-list decision was based on evidence indicating the ESU was at a lower risk of extinction than at the time it was originally proposed for listing. This ESU includes coastal river basins from the Elk River in Oregon to the Klamath River in California. This ESU contains populations of both winter and summer steelhead. The historic range of the steelhead on the North Coast has not been reduced as drastically as it has in other areas of the state and, consequently, is home to the most abundant populations. The Klamath-Trinity river system supports the greatest number of steelhead in California. Steelhead runs in North Coast drainages are comprised mostly of wild fish. Adversely impacting North Coast stocks are logging, agriculture, water diversion, gravel mining, migration barriers and introduction of exotic species.

Northern California. ESU 8, Status: Threatened.

This ESU includes California coastal river basins from Redwood Creek south to the Gualala River. The life history of steelhead in the Northern California ESU parallels those of the Klamath Mountains Province ESU. Steelhead within this ESU include winter and summer steelhead, including what is presently considered to be the southernmost population of summer steelhead, in the Middle Fork Eel River. As with the Rogue and Klamath Rivers, some of the larger rivers in this area have year-round migrating steelhead as well as seasonal runs. While there are no recent population estimates for this ESU, the substantial declines in run size at the region's major dams indicate an overall decline in abundance from historical levels.

Central California Coast. ESU 9, Status: Threatened.

South-Central California Coast. ESU 10, Status: Threatened.

Historically, most streams along the Central Coast had healthy populations of steelhead. Of 122 streams south of San Francisco Bay known to have contained steelhead, 47% have reduced production from historic levels and 33% no longer support populations. Central Coast stocks of steelhead have been impacted heavily by urbanization (particularly in the greater San Francisco Bay Area), agriculture, water diversion, migration barriers and general habitat loss. Populations are not as healthy as northern stocks but less imperiled than southern stocks.

Southern California. ESU 11, Status: Endangered.

Southern steelhead were once found in many of Southern California's streams and rivers -- as far south as the Santo Domingo River in northern Baja California. Originally, Malibu Creek in Los Angles County was thought by NMFS to be the southern-most stream containing a known spawning population; a recent discovery of steelhead in San Mateo Creek in San Diego County has led NMFS to extend this ESU boundary to that point. South Coast steelhead are the most jeopardized of all of California steelhead populations. Numbers have declined drastically in nearly all streams where they exist, and runs have been wiped out from many others. Urbanization, water impoundment and diversions and man-made migration barriers have all contributed to this decline.

Central Valley. ESU 12, Status: Threatened.

Steelhead ranged throughout the tributaries of the Sacramento and San Joaquin rivers prior to the frenzy of dam construction, water development, and watershed perturbation in the 19th and 20th centuries. Populations have been most severely affected by dams blocking access to the headwaters of all major tributaries; consequently, most runs are maintained through artificial production. The decline of naturally-produced steelhead in the Central Valley has been more precipitous than that of the hatchery stocks. Wild stocks are mostly confined to upper Sacramento River tributaries such as Deer, Mill and Antelope Creeks and the Yuba River. Remnant populations are believed to be rebounding in San Joaquin tributaries such as the Stanislaus, the Tuolumne and the Merced rivers.

More Information

Steelhead Recovery Overview

Steelhead Projects