Biological Performance Tests of East Fork Irrigation District's Sand Trap and Fish Screen Facility - Phase I, 1999

Publication Date



fish screen, Coanda, diversion, performance, biological test, salmon, steelhead, descaling, fish injury

Publication place

Portland, OR


Buell & Associates, Inc.


East Fork Irrigation District (EFID) operates a 127-cfs diversion on the East Fork Hood River near Parkdale, OR. Very high glacial sand/silt content of the diverted water requires separation of sand at a facility near the point of diversion. A fish screen incorporated into this facility uses a “prototype” technology with a horizontal profile bar “Coanda” screen in an ogee-shaped weir. Calculated approach velocities significantly exceed generally accepted fish protection criteria, although sweeping velocities are very high and exposure times for fish passing over the weir/screen are less than one second. Biological performance tests using newly buttoned-up Chinook salmon and steelhead fry (30-50 mm) and steelhead smolts (130-260 mm) were conducted in the spring of 1999 to evaluate passage over the weir/screen components of facility in terms of fish injury or latent mortality. Results indicate that no injuries, behavioral anomalies or latent mortalities resulted from passage over the weir/screen for any of the three species / life stages of fish tested. Results are compared to other biological performance studies of fish screens throughout the region. This report concludes that the “Coanda” type fish screens incorporated into EFID’s sand trap and fish screen facility perform at least as well as any of the other screening systems reported and better than most, and that incorporation of this technology into the EFID facility does not pose an injury or latent mortality threat to juvenile salmonid fishes in the system.