Concurrent Sessions A: Emerging Engineering Solutions for Downstream Fish Passage at Big Dams - Downstream Fish Passage For Cle Elum Dam

Throughout the Pacific Northwest region there is a renewed effort to provide upstream and downstream passage at main stem storage reservoirs to access high value resident and anadromous salmonid habitat previously accessible prior to dam construction. Storage reservoirs present many unique challenges to fish passage. The most obvious challenge is dam height, with many dams being from 100 ft to upwards of 500 ft high. Second, storage reservoirs are operated to store and release water seasonally creating reservoir water surface fluctuations of 10’s or 100’s of feet in a year. To date most high dams where downstream fish passage has been established are for hydropower generation facilities with minimal fluctuation in pool elevation. Generally fish passage structures at these facilities consist of manned surface collectors, and trap and haul methods that require high operation and maintenance (O&M) costs. The U.S. Bureau of Reclamation (Reclamation) is actively pursuing the development and construction of downstream passage on a number of its storage reservoirs using new concepts that will allow fish to self-guide into a structure that carries them around the dam and into the downstream river channel; thus, significantly reducing associated O&M costs. One such project is underway at Cle Elum Dam near Cle Elum, Washington. This ecologically and culturally significant fish passage project would restore access to approximately 7.5 square miles of lacustrine (lake) habitat and 29.4 river miles (RM) of riverine habitat—inaccessible for approximately the last 100 years—for anadromous and resident salmonids. This project is being planned for Cle Elum Dam in the Yakima RiverBasin. This collaborative project involves the Bureau of Reclamation (Reclamation), Washington State Department of Ecology (Ecology), Washington State Department of Fish and Wildlife (WDFW), and the Yakama Nation. This project has two components—fish passage facilities design, with Reclamation taking the lead, and a fish reintroduction program developed by the Yakama Nation with assistance from WDFW. In 1907, Reclamation constructed a temporary rock-filled crib dam on the outlet of historic Lake Cle Elum to provide an additional 26,000 acre-feet of irrigation water storage. This was followed by completion of Cle Elum Dam in 1933 at RM 8.2 on the Cle Elum River, which increased storage capacity to 436,900 acre-feet. The Cle Elum River enters the Yakima River at RM 185.6, which flows into the Columbia River at RM 333. It is a zoned earthfill dam with a structural height of 165 feet and a crest length of 1,800 feet. Its maximum pool elevation is 2,240 feet and the spillway crest is at elevation 2,223 feet. Neither facility was constructed with allowance for upstream and downstream fish passage, resulting in the extirpation of anadromous salmon and steelhead populations in the upper Cle Elum subbasin. Historically, tens of thousands of sockeye, coho, and spring Chinook salmon and steelhead returned annually to spawn in Lake Cle Elum and its upstream tributaries. The annual return of salmon was an important source of marine-derived nutrients that helped maintain ecosystem health in the upper Cle Elum River subbasin. Fishing encampments were established by people of the Yakama Nation at both the inlet and outlet of the Lake and it was here that the Yakama people harvested and dried primarily sockeye salmon to sustain them during the winter months and to trade with coastal tribes in the Puget Sound region. In 2012, a drop-pool intake structure, for providing juvenile downstream passage at Cle Elum Dam, was tested by Reclamation’s Hydraulic Investigations and laboratory Services group. A physical model was constructed in the Denver Laboratory using a 1:10 geometric scale. The laboratory investigations demonstrated there were significant fish safety issues with the design. This design concept was based on keeping within NOAA’s criteria for facilitydesign1, which limited the maximum vertical drop to 10 ft and maximum flow velocity to 25 ft/s. However there is some evidence to suggest that under certain conditions fish survival may be good at higher velocities, as long as fish passing through the system are contained within the body of flow so they are not exposed to high shear stresses as they enter the downstream river channel. As a result, new downstream passage criteria and design concepts are now being considered for Cle Elum Dam. Numerical and physical modeling of these concepts is planned by Reclamation to determine the feasibility of these designs and to determine which designs are most conducive and adaptable to a wide range of future dam sites. The long term restoration plan calls for implementing lessons learned and proven methods rising from the Cle Elum project to other main stem dams on the Yakima Project