PNNL

Abstract

Since 1999 Pacific Northwest National Laboratory has conducted several studies for U.S. Army Corps of Engineers to investigate the interaction of juvenile lamprey with turbine intake screens at juvenile bypass facilities on Columbia River dams. Laboratory studies in 1999 and 2000 showed the lampreys were not injured by pressures and sheer forces found in turbines and known to injure salmon. Lab studies also confirmed the lampreys are nocturnal, show avoidance to steady and pulsing lights, and prefer to stay at the bottom or sides of passageways. Swim speed studies showed that lampreys are slower than salmonids (5.2 body lengths/s burst swim speed versus 9 to 12 BL/s for juvenile salmon). Juvenile lamprey were also highly susceptible to impingement on the 1/8-in.extended length submersible bypass screens (ESBS) used in bypass systems at Lower Granite, Little Goose, McNary, and Bonneville dams. In laboratory studies, video cameras recorded the progression of events from impinged to stuck as water velocity increased from 0 to 2.4 ft/s, the average perpendicular velocity at a typical turbine bypass screen. Our studies showed this exceeds the lamprey?s burst swim speed of 2.3 ft/s. Horizontal and vertical orientation of the 1/8-in. bar screens were compared and test results showed lamprey were twice as likely to become stuck in screens with bars oriented horizontally. Video observations recorded during field studies in 2000 and 2001 at McNary Dam confirmed impingement seen in lab studies. This study also demonstrated that juvenile lamprey could be effectively PIT tagged and enumerated if they are diverted by the turbine intake screens to fish collection facilities. Travel time distributions within the juvenile bypass system differed for lamprey and fall chinook smolts possibly showing lamprey?s ability to adhere to smooth surfaces in the system.