Staff paper: Review of Fish Passage Technologies at High-Head Dams

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This paper responds to a strategy in the Council’s 2014 Columbia River Basin Fish and Wildlife Program addressing mitigation of the impacts of hydropower dams on anadromous fish in areas where dams block fish passage to historic habitat. The first phase of the three-phase approach calls for studies and evaluations to inform what is known generally about fish passage and specifically about the quality of the habitat in the blocked waters of the Upper Columbia above Chief Joseph and Grand Coulee dams. Neither dam was built with fish-passage facilities.

The habitat evaluation is being conducted for the Council by the Spokane Tribe of Indians. In this paper, which can be viewed as a corollary to that evaluation, Council staff evaluates information from passage studies at Chief Joseph and Grand Coulee, and at other dams where fish passage has been studied or completed. Included in the evaluation are dams in Washington and Oregon, on the border of Oregon and Idaho, and in California and Pennsylvania. In order to better understand each location, staff compiled standardized information into case studies, summarizing information gleaned from design documents, annual reports, and from personal communications with project staff.

The paper explores six themes that could apply in planning and providing fish passage at high-head dams such as Chief Joseph and Grand Coulee:

  1. Allow adequate time for evaluations and feasibility studies
  2. Do not evaluate or compare existing fish-passage projects on the basis of cost, as variations in site characteristics and the age of passage systems make cost comparisons inaccurate
  3. Understand and account for differences in site characteristics
  4. Stay up to date with passage technologies, as fish passage technology is evolving and improving
  5. Collaborate with project owners, regulators, fish and wildlife agencies, tribes, scientists and interested parties as it can be critical to successful, large-scale anadromous fish passage projects
  6. Consider developing a science-based decision framework for new projects to help organize and assess all the biological, environmental, hydraulic, technical, and economic data for a range of passage alternatives under consideration at each site

The paper addresses high-head dam passage for both adult and juvenile fish and recommends that fishery managers working on and studying passage should consider the following:

  • What is the end goal or objective for fish? For example, the goal could be to achieve a natural, self-sustaining population, or it could be to gain cultural, biological and economic benefits as the result of passage.
  • Where should the juvenile fish collector be located? Possible options are in the forebay near the dam, in the reservoir, at the head of the reservoir, or in tributaries upstream of the reservoir
  • What types of fish passage systems should be evaluated at each project?

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