PNNL

Abstract

Providing fish passage at high-head hydroelectric facilities can be prohibitively expensive, especially for owners of smaller projects, due to the challenges associated with maintaining acceptable velocities and pressures for a large change in elevation. Traditional solutions involve large, expensive structures typically made of concrete, such as fish ladders or fish locks. Collecting and hauling operations using transport trucks can also be prohibitively expensive due to high operating costs. A new solution to high-head downstream fish passage is required to provide responsible stewardship of aquatic resources while retaining the economic viability of some hydropower facilities. An innovative, cost-effective system for downstream fish passage at high-head hydropower facilities has been developed, and is currently awaiting prototype-scale testing. The system uses engineered decompression raceways to safely pass fish by regulating pressures and controlling bypass flows. The development of the decompression raceway allows proven and inexpensive in-conduit screening systems, such as Eicher-type or MIS-type screens, to be used at high-head hydropower facilities because it solves the problem of controlled decompression at the discharge location. Results from extensive site specific Computational Fluid Dynamic model tests used to verify the hydraulic performance of the decompression raceways will be presented, as well as results from hyperbaric pressure tests verifying low mortality rates in test specimens. This presentation will be of interest to owners and developers of hydropower facilities looking to add fish passage at a high-head project.