Columbia-Pacific Northwest Region

Clear Creek Dam Fish Passage Project

In 1914, Reclamation constructed the concrete thin-arch structure dam on the North Fork of the Tieton River. The resultant reservoir that formed is known as Clear Lake and the impounded water was for Yakima Project irrigation use.

Originally, the dam was 63 feet high, 161 feet long, with two pipe outlet conduits, and it was designed to be overtopped during flood flows. As originally constructed, the dam only impounded a capacity of 1,700 acre-feet. In 1918, the dam was raised by 21-feet to its structural height of 84 feet. with a current crest elevation of 3016 feet. Gravity blocks were added at either end of the original arch section, effectively increasing the storage capacity of the reservoir. The rebuilt structure was now 404 feet long and impounded 5,300 acre-feet of water.

With construction of Tieton Dam/Rimrock Lake, downstream in 1925, Clear Creek Dam essentially became obsolete as a storage reservoir and its primary function shifted from water storage for irrigation to recreation. However, Clear Lake is still a Yakima Project reservoir and could supplement or augment irrigation water or flows, respectively.

Clear Lake provides negligible irrigation flow because it has a small storage capacity (5,300 acre-feet) and is located upstream from Rimrock Reservoir. However, in short water years and to offset irrigation and fishery minimum storage requirements in Rimrock Lake, Clear Lake might provide some benefit to the downstream storage demands. In normal runoff years, Clear Lake is operated to maintain an elevation of 3011.30 to 3011.40 feet for Yakima Project uses, including fish passage and recreation. Inflow and outflow are essentially equal and most all flow passes over a spillway weir crest at elevation 3011.00 feet. For the past 31 years, one 36-inch slide gate has been kept open 6 inches to prevent the outlet gate area from silting up. From mid-August to October 5th, Reclamation attempts to hold the lake at elevation 3011.40 feet; this provides the most effective passage through the fish ladder and maintains stable downstream spawning flow. In years of late-season, high-volume runoff, this elevation is nearly impossible to hold unless large releases are made through the dam’s slide gates; this is undesirable because the fish are attracted by the high gate releases and away from the spillway flows which supply the fish ladder passage.

A population of bull trout spawns in the North Fork Tieton River above Clear Creek Dam, and this river is designated as critical habitat for bull trout. Studies also found this population of bull trout is disconnected by the dam. Many North Fork Tieton fish migrate downstream from the dam, where they find favorable rearing habitat in Rimrock Lake. During the summer, adult bull trout return to the North Fork Tieton to spawn, congregating in the stilling basin below Clear Creek Dam, where they are attracted to the cold water flowing through the outlet works. These fish are unable to migrate upstream because there is no upstream passage at the dam. In addition, the strong homing instinct of these fish prevents them from seeking spawning habitat elsewhere. As a result, these adult North Fork Tieton River fish remain in the Clear Creek Dam stilling basin and do not contribute to the North Fork Tieton spawning population.

When Clear Creek Dam was rebuilt in 1992, two fish ladders were added to the bedrock spillway of Clear Creek Dam. These ladders, constructed in 1993, are in the upper and lower section of the spillway. The lower ladder is a series of four denil ladders interspaced with resting pools located on the right bank of the spillway. The upper ladder is a pool-and-weir design constructed on the left side of the spillway channel. The denil ladder is considered too steep for successful passage and easily becomes clogged with sediment and gravels. As a result of studies conducted in 2012 through 2014, it was determined that there is no evidence that fish successfully migrated upstream through the fish ladder, and the fish ladder was all but abandoned (fish ladder is still there but maintenance has ceased).

Fish passage at Clear Creek Dam has been under consideration since 2005 when a Pre-design Memorandum was written exploring alternative methods of fish passage at the site. Due to funding limitations and uncertainties about the ability of adult bull trout to pass through the spillway at that time, the Clear Creek Dam Fish Passage project was put on hold. Reclamation with the support of our partners reinitiated the Clear Creek Dam Fish Passage design work and is committed to finding a solution to the fish passage barrier problem at Clear Creek Dam.

The Bureau of Reclamation proposes to construct and operate a fish passage system at Clear Creek Dam in Yakima County, WA. Clear Creek Dam Fish Passage is iified in the first phase of the Yakima Basin Integrated Plan, which is supported by our partnership with the U.S. Forest Service, U.S. Fish and Wildlife Servic, the Washington State Departments of Ecology and Fish and Wildlife and the Confederated Tribes and Bands of the Yakama Nation and other local, state and federal entities. The proposed fish passage system will replace a non-functioning ladder on the spillway constructed in 1993.

The purpose of the CCDFP Project is to improve the long-term viability of the North Fork Tieton bull trout population by allowing bull trout to move freely between spawning and rearing habitat areas. The long-term viability of bull trout, in the CCDFP Project area, would be accomplished through the following:

implementation of fish passage that complies with current regulatory criteria

reduction in take

An additional benefit of providing upstream fish passage include the ability to reintroduce salmon and steelhead in the future.

Please refer to the map linked below to view the affected areas.

Until passage improvements are accomplished, USFWS, Reclamation, and WDFW will continue capturing bull trout from below Clear Creek Dam and transporting genetically identified North Fork Tieton River fish around the dam so they can reach spawning grounds in the North Fork Tieton River. Fish capture and transports were conducted from 2016 through 2023.

Reference Documents
12/2023	Clear Creek Dam Fish Passage Draft Environmental Assessment PDF 5.0 MB
12/2023	Clear Creek Dam Fish Passage 12 Foot Drawdown Map PDF 1.34 MB
12/2023	Clear Creek Dam Fish Passage Affected Facilities Map PDF 1.74 MB

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