Fish Passage Technologies: Protection at Hydropower Facilities (Part 6 of 11)

he implementation of downstream mitigation for fish passage at hydropower facilities has three distinct goals: to transport fish downstream; to prevent fish from entrainment in turbine intakes; and to move fish, in a timely and safe manner, through a reservoir.1 A range of mitigation methods for downstream passage and for prevention of turbine entrainment exist, and some have been applied with more success than others. The so-called “standard” or “conventional” technologies are mainly structures meant to physically exclude or “guide” fish to a sluiceway or bypass around the project and away from turbine intakes by means of manipulating hydraulic conditions. Other “alternative” technologies attempt to “guide” fish by either attracting or repelling them by means of applying a stimulus (i.e., light, sound, electric current). Many theories have been applied to the design of downstream passage systems and further experimentation is underway in some cases (see box 4-1).