Causes of Fish Lift Shutdowns on U.S. East Coast Hydroelectric Dams

Hydroelectric dams in the northeastern United States pose a challenge to the upstream spawning migrations of anadromous fishes, such as American Shad Alosa sapidissima, Alewife A. pseudoharengus, Blueback Herring A. aestivalis, Atlantic Salmon Salmo salar, and Sea Lamprey Petromyzon marinus. One response has been the construction and operation of fish lifts. A drawback of this solution is that fish lifts can be shut down. This study sought to determine how often fish lifts on major northeastern rivers (including lifts at the Cataract, Lockwood, and Milford dams in Maine; Holyoke Dam in Massachusetts; Scotland Dam in Connecticut; and Conowingo Dam in Maryland) shut down during their respective passage seasons and the causes for these shutdowns. We found that these lifts did not operate for 8–26% of their passage seasons, on average, with the mean season length lasting between 49 and 205 d. The causes for shutdowns were categorized as physical, mechanical, scheduling, other, or none given, with the primary cause varying among dams. Our results demonstrate an important weakness of fish lifts as a passage solution and, in turn, highlight the need for measures that limit disruptions to lifting where dam removal is not possible and strengthen the case for dam removal.