During their upstream migration from the Sargasso Sea, the first anthropogenic obstacle encountered by juvenile American eel (Anguilla rostrata) in the St.-Lawrence River (Canada) is a large run-of-the-river hydroelectric power dam. The facility is located at Beauharnois, downstream of Lake Ontario, the largest and richest growth habitat of this river system. The second and last anthropogenic obstacle is another large run-of-the-river hydro dam, the Moses-Saunders power Dam, located 82km upstream of the Beauharnois generating station. Both facilities are equipped with eel ladders. From 2011 to 2015, 15,500 juvenile eels were Pit-tagged at the exit from the Beauharnois eel ladder and more than 40% were observed on the Pit tag detectors at the Moses-Saunders eel ladders within 7 years of the first tagging. Details on the upstream migration parameters of the St.-Lawrence juvenile American eel will be presented.