SONGS coastal view

Mitigation Projects > Behavioral Barriers

Behavioral Barriers

midwater school of pile surfperch
Midwater school of pile surfperch (Rhacochilus vacca).
Photo by Richard Herrmann

Condition B of the SONGS permit requires SCE to install and maintain behavioral barrier devices at SONGS Units 2 and 3 to reduce fish impingement losses. The impact studies for the operation of SONGS Units 2 and 3 conducted by the Marine Review Committee (MRC) between 1983 and 1991 found that annual losses of juvenile and adult fish in the cooling water systems under normal operations averaged about 20 metric tons. These losses are in addition to entrainment losses of fish eggs and larvae that pass through the screens and are killed by the elevated water temperatures and velocities in the cooling system. Based on these findings by the MRC the California Coastal Commission (CCC) requires SCE to reduce impingement losses by at least 2 metric tons per year. Although the SONGS permit does not specify any criteria for evaluating the effectiveness of these devices, the CCC determined that behavioral barrier devices be tested on an experimental basis, and implemented if they reduce impingement by at least 2 metric tons per year, which is equivalent to at least 10% of the average loss due to impingement.