21st Century Improvements in American Eel Upstream Passage on St. Lawrence River

The two mainstem Saint Lawrence River hydroelectric power dams, Beauharnois (est. 1930) and Moses-Saunders (est. 1958), both have upstream passage facilities for juvenile American eel, Anguilla rostrata.  The first dam encountered by upstream migrants, Beauharnois, has two eel ladders constructed on each side of the facility in 2002 and 2004.  Moses–Saunders also has ladders at each end of the combined facility with operations starting in 2006 and 1974, respectively.  Approximately 600,000 eels have passed upstream of Beauharnois and 300,000 at Moses-Saunders since 2001.  The range of individuals passing in a single season at Beauharnois was ~22,500 in 2013 to ~88,000 in 2008.  Comparatively, the range of the combined total at Moses-Saunders was ~14,000 in 2007 to ~52,000 in 2012.  Eel passage at Beauharnois shifted entirely to one of the two ladders in 2007.  Greater use of one of the two Moses-Saunders ladders occurred during 2007-2010, shifting to an even distribution of use in 2012 and 2013.