Information on steelhead abundance in southern Oregon before the 1950s is sketchy, coming primarily from Rivers' (1957, 1963) studies of Rogue River Basin steelhead. Regarding late 19th-century fisheries in the Rogue River Basin, Rivers (1963, p. 56) reported that

cutthroat and downstream migrant steelhead were abundant and easily caught by the hundreds from streams all through the settled portions of the basin.... The headwaters of the Applegate River, the Illinois River, Jumpoff Joe Creek, and Grave Creek were sections of the basin preferred for trout fishing because of the easy access afforded by mining roads.

Historical information for northern California is even more scarce, although Snyder (1925) noted that trout (including steelhead) were declining in the Klamath River Basin at that time.

Results of these quantitative evaluations are summarized in Table 13. Most of the stocks in the region are in significant decline, even with hatchery production included. Natural production appears to be below replacement for all stocks for which we have this information; given the qualitative assessments, there is little reason to believe that other stocks are in better condition (with the possible exception of the Smith River winter run mentioned above). We are unable to demonstrate that any steelhead stocks in this region are naturally self-sustaining.

Total abundance varies widely among populations within the proposed ESU, with several populations having run sizes of 10,000 or more fish. The heavily hatchery influenced summer/fall run from the Klamath River may total 100,000 or more fish. At the other extreme, there are a number of populations with less than 1,000 spawners per year.

In this section, we briefly discuss human activities that may have affected anadromous salmonid distribution and abundance within the geographical area of the proposed ESU. This is not meant to be a comprehensive analysis; rather, it is intended to briefly outline the nature and scope of activities that have occurred.

The effects of human activities on salmonids in the Klamath River Basin have been recognized to the extent that in 1986 Congress passed the Klamath River Basin Fishery Resources Restoration Act (16 U.S.C. 460ss-460ss-6, Public Law 99-552) to restore and maintain anadromous fish populations. The Klamath Act (p. 592) states in part:

...floods, the construction and operation of dams, diversions and hydroelectric projects, past mining, timber harvest practices, and roadbuilding have all contributed to sedimentation, reduced flows, and degraded water quality which has significantly reduced the anadromous fish habitat in the Klamath-Trinity River System.

A number of dams and diversions have been constructed within the Klamath Mountains Province during the past century. Dams have been installed for the purposes of flood control, hydropower, recreation, and domestic, industrial, and agricultural water supply. Not all of the dams have survived to the present time. Rivers (1963) and the Klamath River Basin Fisheries Task Force (KRBFTF 1991) chronicled the history of dams and diversions in the Rogue and Klamath River Basins, respectively. This document will discuss only those dams which have had a substantial impact on salmonid distribution and abundance.

Rogue River Basin--Gold Ray Dam (RKm 203) was originally completed in 1905 and rebuilt in 1940 (Rivers 1963). Fish ladders of various types and effectiveness have been installed at Gold Ray since 1906 (Rivers 1963). The Oregon Department of Fish and Wildlife has used the present ladder as a counting station for anadromous fish since 1968 (Evenson et al. 1982). Savage Rapids Dam (RKm 173) was completed in 1922 and has been laddered since 1923 (Rivers 1963). Construction of Lost Creek Dam on the Rogue River (RKm 254) was completed in February 1977; the primary purpose of this dam is flood control (ODFW 1994). Approximately 13% of the Rogue River Basin is located above Lost Creek Dam (ODFW 1994), which has no provision for fish passage (Cramer et al. 1985). Cole Rivers Hatchery operates as a mitigation hatchery for Lost Creek Dam; summer and winter steelhead as well as coho and spring chinook salmon are reared there (Evenson et al. 1982). Applegate Dam began operation in November 1980 at RKm 75 of the Applegate River (a tributary to the Rogue River at RKm 154) (ODFW 1994). Applegate Dam has no fish passage facility. Adult steelhead broodstock are collected below Applegate Dam, and eggs are cultured at Cole Rivers Hatchery.

Lost Creek and Applegate Dams are part of a three-dam flood control project in the Rogue River Basin (Fustish et al. 1989). The third dam, Elk Creek, has not yet been constructed. Elk Creek enters the Rogue River at RKm 244, and the proposed dam would be at RKm 2.7 on Elk Creek (Flesher et al. 1990).

Klamath River Basin--Anadromous fish passage to the upper Klamath River has been blocked at Klamath Falls, Oregon since the construction of the Link River hydroelectric dam in 1895 (KRBFTF 1991). Two hydroelectric dams were built by the California Oregon Power Company (Copco) northeast of Yreka, California in the early 1900s: Copco 1 in 1917 and Copco 2 in 1925 (KRBFTF 1991). No fish passage was provided, but a mitigation hatchery operated downstream on Fall Creek until 1948 (KRBFTF 1991). In 1958, Copco completed another dam below Keno, Oregon, presently called the J. C. Boyle Dam. Iron Gate Dam, completed in 1962, was ostensibly constructed to regulate the adverse flow regimes caused by Copco 1 and 2; however, it is also used for hydropower production (KRBFTF 1991). The dams described above block anadromous fish access to 120 km of mainstem habitat in the Klamath River and tributaries to that part of the river; it is estimated that this could provide spawning habitat to 9,000 chinook salmon and 7,500 steelhead (KRBFTF 1991).

The Trinity River is the largest tributary to the Klamath River; two diversion dams, Trinity and Lewiston Dams, were built on the upper Trinity River in 1964 to divert water to the Sacramento Basin as part of the Central Valley Project (KRBFTF 1991). The Trinity River Fish Hatchery was constructed at Lewiston Dam to mitigate the loss of fish passage.

It is relatively simple to quantify habitat loss due to dam construction; however, other activities that may effectively render habitat unusable for steelhead (e.g., through sedimentation, gravel mining, or water withdrawal) are more difficult to quantify.

Timber harvesting and associated road building activities occur throughout the Klamath Province on Federal, State, private, and tribal lands. These activities may increase sedimentation and debris flows and reduce cover and shade, resulting in aggradation, embedded spawning gravel, and increased water temperatures. The majority of forest lands in the Klamath Basin are managed by the U.S. Forest Service (KRBFTF 1991). The Klamath Mountains Province includes holdings of the Klamath, Rogue River, Shasta-Trinity, Siskiyou, and Six Rivers National Forests. According to the Forest Ecosystem Management Assessment Team, FEMAT (USFS and BLM 1994), 56% of the land in the Klamath Province is owned by the U.S. Forest Service, and 9% is owned by the Bureau of Land Management. Recognition of the importance of timber management activities on aquatic habitat is demonstrated in the provisions for riparian reserves and key watersheds described in FEMAT (USFS and BLM 1994).

The Rogue and Klamath Basins have been sites of active mining, primarily for gold, since the mid-1800s (Rivers 1963, KRBFTF 1991). Suction dredge mining results in sedimentation, which affects viability of salmonid eggs and juveniles, reduces holding habitat for adult salmonids, and reduces the standing crop of aquatic insects that salmonids prey upon (Rivers 1963, KRBFTF 1991). Suction dredging in the region continues to the present day (KRBFTF 1991). Dry rock (lode) mining introduces cyanide to the water and may cause fish kills (Rivers 1963, KRBFTF 1991). Lode mining for gold, copper, and chromite in the Klamath River Basin continued as recently as 1987 (KRBFTF 1991).

Irrigation in the Rogue Basin began in the late 1880s (Rivers 1963). Loss of salmon and steelhead to unscreened irrigation diversions was recognized as early as 1901 (Rivers 1963); however, the significance of these losses was not generally accepted. Loss of salmonids to unscreened irrigation diversions continues to the present day and is estimated at 1 million juvenile salmonids per year in the Rogue Basin (Palmisano 1992).

Threshold Assessment

Our quantitative and qualitative analyses revealed the following:

1. Although historical trends in overall abundance within the ESU are not clearly understood, there has been a substantial replacement of natural fish with hatchery produced fish.
2. Since about 1970, trends in abundance have been downward in most steelhead populations within the ESU, and a number of populations are considered by various agencies and groups to be at moderate to high risk of extinction.
3. Declines in summer steelhead populations are of particular concern.
4. Most populations of steelhead within the area experience a substantial infusion of naturally-spawning hatchery fish each year. After accounting for the contribution of these hatchery fish, we are unable to identify any steelhead populations that are naturally self-sustaining.
5. Total abundance of adult steelhead remains fairly large (above 10,000 individuals) in several river basins within the region, but several basins have natural runs below 1,000 adults per year.