The McKenzie River Basin of Oregon drains a 1,300 square mile area of the western slope of the Three Sisters range of the Cascade Mountains and joins the Willamette River 90 miles to the west, just north of Eugene. It reaches a height of 10,358 ft. at the top of the Three Sisters Wilderness and drops to 504 ft. at the confluence with the Willamette. The river is initially formed underground in lava chambers created during recent volcanic activity. This unique aquifer acts to filter the water and maintain it at very cold temperatures. This water is the primary water source for the city of Eugene, Oregon (pop. 160,000). Recent chemical tagging studies have shown that the water reaching the lower reaches of the river is largely the result of Cascade Mountain snow fall about seven years in the past. This process has resulted in an environment tailored to the requirements of the native West Coast Salmonid species.

The McKenzie River forms at Clear Lake, below the lava fields, and goes south over two falls, Sahalie and Kooshia. From here the river flows into the reservoir formed behind Trail Bridge Dam where it is piped through a mountain to the Carmen-Smith power plant and then released back in the river. Continuing south, the river goes underground beneath an ancient lava field emerging at the well named and very cold Blue Pool. During conditions of high flow in the river, water also flows on the surface and cascades into the pool over Tamolitch Falls. From here the river continues south for several miles and then turns west for about 80 miles to the confluence. The McKenzie is joined by its major tributary, the South Fork of the McKenzie, about 10 miles to the west. The South Fork flows for about 30 miles to the south and east of the mainstem of the river.

Historically, this area was the home of several Native American tribes and was first seen by Westerners in the early 19th Century when discovered by a group of Canadian fur traders led by Donald MacKenzie, for whom the river is named (yes, the spellings does not match). Today about 64% of the basin is federal land and only in the lower 10 miles is the river bordered by agriculture and urban sprawl. The river supports fishing and boating activities.

Wild Fish Species in the McKenzie River Basin

The following are the most notable and important species endemic to the basin:

  • Bull Trout (ESA listed as Threatened)

  • Coastal Cutthroat Trout

  • Spring Chinook salmon (ESA listed as Threatened)

  • Mountain whitefish

  • Rainbow “McKenzie Redside” trout

  • Pacific Lamprey (listed as a Species of Concern by the State of Oregon)


This section will be broken into two parts. The first will describe the various anthropogenic threats affecting the fishery overall. Following that, we will cover concerns specific to the species listed above.

General Threats to the McKenzie Fishery:

While the river is mostly unaffected by human development, a major factor has been the various dams placed in the river. Leaburg Dam, about 11 miles above the confluence, was built by the local power and light company in 1929. Once a barrier to fish spawning in the upper river, the dam now supports two fish ladders, which seem to provide little hindrance to movement. Trail Bridge Dam, built in 1963 as a part of the Carmen-Smith power generation facility is 70 miles above the confluence and has been a barrier to fish movement and resulted in the isolation of the remaining Bull Trout population in the Willamette Basin. The Willamette Basin Flood Control Project, managed by the Army Corps of Engineers (COE) built two flood control structures in the McKenzie Basin, Cougar Dam (1963) and Blue River Dam (1969). The former dam cut off approximately 25 miles of prime salmon spawning and rearing areas. Dams have also altered river temperatures, flow regime, and downstream transport of large wood and sediment.

Besides the impact of the dams on habitat quality and fish movement, there has been some impact due to logging and loss of shade and rearing habitat in the lower reaches of the river due to urban, rural and agricultural development. Recent water quality monitoring by the Eugene Water & Electric Board identified urban storm drains as a major threat to Mckenzie River water quality. In future years, it is likely that the impact of warming and associated timber loss due to fires will become factors stressing fish populations. To date, given the unique hydrology of the river as discussed above, this has not yet become a major factor.

Threats to specific species:

  • Bull Trout: Currently, the Oregon Fish Department of Fish and Wildlife agency (ODFW) believes that there are presently about 1,000 Bull Trout in the Upper Willamette Basin. It is likely that the largest population of these fish are isolated above Trail Bridge Dam on tributaries of the upper McKenzie River. Locally, angling for these fish is banned and some efforts to establish new isolates of Bull Trout by moving juveniles to promising habitat in the South Fork and Middle Fork of the Willamette River have been undertaken, but the efficacy of these efforts is not established. However, at present the resident Bull Trout population of the Mckenzie River Basin appears to be stable.

  • Coastal Cutthroat Trout: At present, these fish seem to be adapted to a larger range of habitat then other salmonids as they are found in lower reaches and in the low lying and warmer streams on the west side of the Willamette River.

  • Spring Chinook salmon: This run of salmon are unique to the Willamette Basin and are assumed to have evolved to overcome the natural barrier at Willamette Falls near the confluence with the Columbia River. Prior to the creation of a fish ladder at the falls, spring was the only time of year when flows were high enough for fish to pass upstream. Historical records indicate that in the 19th Century, about 275,000 Spring Chinook returned to the Willamette River with about 40% of these spawning in the McKenzie River. In the last few years, about 1,000 salmon spawned in the McKenzie River (<1% of their historical numbers). The factors that have led us to this situation are not unique and involve loss of habitat, over harvest, hatchery competition (and possibly disease) and hydropower (e.g., dams). As the McKenzie Spring Chinook is presently the largest and most genetically intact population in the basin, it has been designated as a “legacy” or “stronghold” population for these fish. What is being done to see that these fish recover will be discussed below.

  • Mountain Whitefish: These fish are endemic to the western states of North America and likely were present long before most other salmonids. As they are generally found in low numbers in the basin and are not considered a recreational target, they have received little attention. Whether this neglect is to their benefit or not remains an open question.

  • Rainbow “Redside” Trout: McKenzie Rainbow trout, or “Redsides” as they are known locally, are plentiful in the upper reaches of the river, but much less common in the middle reaches and then plentiful in the lower river from Hendricks Bridge to the confluence. As the sections of the river where native trout are largely absent are ones where ODFW plants large number of hatchery spawned rainbow trout from an out of basin stock raises concerns.

  • Pacific Lamprey: These fish are endemic to the Mckenzie and as indicated above, are a “species of concern” for the state of Oregon. As the lamprey were an important source of food for Native Americans and an important religious symbol for their culture, their status should not be ignored. Still, there is not consistent monitoring of their numbers and distribution, and we are just now learning what it takes to provide a useful passage for a fish that cannot swim over barriers.


Results of Litigation:

By the late 1990s, it was apparent that the Upper Willamette Basin fishery of anadromous salmonids (Chinook salmon and winter steelhead) were in serious decline. This was reinforced by the listing of these fish and Bull Trout in 1998 and 1999. Responding to this concern, 12 organizations representing conservation, fishing and Native American interests challenged the FERC relicensing of the Carmen-Smith power and dam complex on the grounds that it did not provide fish passage and therefore was a detriment to recovery. Following an agreement with the Eugene Water and Power Board which owned the dam, discussions of how the problem should be dealt with have lagged on, with the owners finally announcing that in 2019 a fish ladder allowing free movement of fish would be implemented. As there is relatively little spawning ground above the dam, the major impact of this resolution will be to allow expansion of the range of McKenzie River Bull Trout.

In 2007, the Willamette Riverkeepers and the Northwest Environmental defense Fund filed suit against the National Oceanic and Atmospheric Administration (NOAA) for a failure to issue a biological opinion regarding the management of listed fish in the basin. This settlement resulted in a consultation by the National Marine Fishery Service (NMFS), a division of NOAA along with the US Fish and Wildlife Service to release a Biological Opinion (BiOp 2008) clarifying that the existing programs in the basin posed a continuing threat to the ESA listed fish and specified specific threats, needed changes and timing for these activities to occur. A positive outcome of the BiOp 2008 was the initiation of much increased monitoring of status of the threatened species and, at the same time, specific timing for major corrective actions which were the responsibilities of various federal and state agencies. Unfortunately, a number of these requirements came and went without an apparent action, while the monitoring reports documented a continuing decline of Spring Chinook salmon in the river. This perspective was reinforced by a 2016 report by NOAA fishery scientists confirming this perspective.

Responding to this situation, the McKenzie Flyfishers, Steamboaters and the Western Environmental Law Center (WELC) initiated a lawsuit charging that the Army Corps of Engineers (Corps) and the Oregon Division of Fish and Wildlife (ODFW) had failed to meet their obligations required in the BiOp 2008. This suit resulted in a settlement with the Corps in which that agency agreed to go forward with completing fish passage at Cougar Dam and to limit the release of hatchery Chinook salmon until there was a NMFS approved plan for hatchery management. In 2017, the Corps released plans for structural changes to Cougar Dam intended to support efficient downstream passage of fish from above the dam. This work is expected to be completed by 2022, so it will be at least until 2026 before we will expect to see any impact of this action on the recovery of natural spawning Chinook salmon in the McKenzie River. As a part of the same suit, the ODFW was ordered by the court to meet specific standards to avoid harmful genetic exchange between hatchery and the threatened natural spawning salmon. The effects of actions proposed by ODFW to address this issue is expected to manifest in the 2018 spawning season, so this data will be looked at with interest when it becomes available in early 2019.

Noting that major portions of the BiOp 2008 had not been addressed and the continuing decline in the listed fish, in 2018 the Native Fish Society, joined by the Northwest Environmental Defense Center and WildEarth Guardians filed suit against the Corps and NMFS for their failure to implement the requirements of the 2008 BiOp. The suit requests that the courts compel the agencies to accelerate their compliance with this document and reinitiate consultation under the ESA.

Citizen Science:

As noted above, the status of native Rainbow Trout in the Mckenzie River has been a question for a number of years, given that hatchery origin Rainbow Trout of various stocks had been introduced in the river for decades. In 1963, the Leaburg hatchery was established to provide some mitigation for the loss of fish due to the presumed effects of the federal dams on the river. The numbers and placement of hatchery fish released have varied from year to year. However, and open question remains regarding the impact of introducing large numbers of hatchery origin trout into wild trout reaches of the river where they could compete for resources and spawn with or harvest juvenile trout and salmon. To partially mitigate some potential effects, for several years only sterile (triploid) variants of the hatchery stock were released into the river.

In 2009, an opportunity arose to answer some of the open questions when the ODFW decided to cease stocking hatchery rainbow trout in a 5.1 mile section of the Lower McKenzie River. In response, a group of local anglers, with support from the local ODFW field office, established the Lower McKenzie River Trout Population Study with a protocol and data collection scheme designed to monitor changes in fish density of the section. Starting in 2010 and finishing in 2013, the study documented a more than doubling of the density of native rainbow trout in the section over those four years (initially 729 per sq. mi. in 2010 and increasing to 2,143 per sq.mi in 2013). Interestingly, about the same proportional growth in numbers was observed for Cutthroat Trout in the study section and the increases were observed in all age classes. This data strongly suggests that the presence of hatchery Rainbow Trout is substantially suppressing the native trout populations. The question of the effects of hatchery trout on juvenile Spring Chinook salmon productivity has been suggested, but is yet to be examined.


Despite some scars from development activities and the effects of dams on the river, the McKenzie River has many friends in the Upper Willamette Basin and has benefited from increasingly aggressive efforts to restore and enhance the functioning of the watershed and reverse the decline of the fishery. The McKenzie River Trust stands out as an organization dedicated in these pursuits. Since the late 1980’s, they have grown as a regional land trust, conserving and protecting more than 3,400 acres of western Oregon Land. Much of this is in riparian areas of the McKenzie which are vital to the river’s biological integrity and biological functioning.

Another strong advocate for the McKenzie River is the McKenzie Watershed Council, which has initiated and coordinated a number of important floodplain enhancements projects. For instance, in the lower South Fork of the McKenzie River, below Cougar Dam, the council is working with the U.S. Forest Service to restore the 4.2 mile section which is expected to become prime habitat for the rearing of Spring Chinook and Bull Trout as these fish pass through the dam while also supporting a number of other species. The council is also involved in a number of additional riparian enhancement projects at various sections of the river. While the impact of each of these projects is likely to be fairly small in terms of recovery of the biological productivity of the McKenzie River, we have come to understand that the decline of the river can largely be assigned to the cumulative impact of many local changes, frequently man-made. By restoring as much of the river as we are able to functioning as it has in the past, it is not unreasonable to expect that the aggregate impact will move us toward recovery of the native fisheries.

Conservation Partners within the Basin

McKenzie Watershed Council

McKenzie River Trust

McKenzie Flyfishers

Trout Unlimited chapter


Eugene Water and Electric Board (EWEB)

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