Design Guidelines for Pacific Lamprey Passage Structures

Historically, hydraulic conditions within fishways of the Columbia basin were optimized to facilitate the passage of salmonids.  Declines among other anadromous species, including Pacific lamprey (Entophensus tridentatus) have led to fishway modifications, operational changes and construction of innovative, species specific structures, such as Pacific Lamprey Passage Structures (LPS) in an effort to improve Pacific Lamprey passage while minimizing potential impacts on salmonid passage.  Currently, the LPS are being considered for implementation at a wide variety of projects from low-head irrigation dams to large mainstem hydroelectric projects.  In an effort to aid these efforts, we compiled design guidelines for use in the development of LPS systems.  Guidelines include recommendation on overall system configuration, major components of LPS and structural features (climbing ramps, traversing ramps, rest boxes, water supply systems, and collection systems), operational recommendations, and detailed evaluation of system limits with respect to system discharge, slope, and physical modeling of lamprey drag.  The design criteria also include a digital CAD-based “parts library” of major components to facilitate rapid design of LPS systems in new locations.  Our hope is the guidelines will facilitate cost-effective implementation of other structures at an increasing range of passage barriers in the Pacific Northwest.