The Richelieu River, an outlet of Lake Champlain, empties into Lake Saint-Pierre near Sorel. Juvenile eel migration in the river is hindered by two obstacles: the Saint-Ours dam and the Chambly dam.
The Chambly dam, located 70 km from the river mouth, is a concrete weir built in 1965 whose function is limited to maintaining the upstream water level. The eel ladder, designed and manufactured by AECOM and installed in 1998, consists of a substrate with molded plastic studs inserted in a thick aluminum casing. After climbing the eel ladder, the eels fall directly into the Richelieu River, or into a net pen where they can be collected.
AECOM has been monitoring eel passages at the Chambly dam since the eel ladder was commissioned. A photoelectric counter, developed and supplied by AECOM, records eel passages. The counter’s accuracy is periodically validated by comparing its estimate with the number of eels captured during a given period. A communication system linked to the counter enables daily transmission of counts and remote access to its operating parameters. The length of collected eels, or of a subsample, is also measured every two weeks. Finally, a data logger monitors water temperature at the exit of the ladder.
Every week during the operation season, an AECOM team performs on-site monitoring and maintenance.
Tasks include:
- Verification of the ladder flows and the eel counter computer system
- Physical inspection of the ladder components and capture setup
- Eel size measurements
- Production of the operations report
