09/10/2014 12:16 EDT | Updated 11/10/2014 05:59 EST

OPG warns of high river water levels near dams in northern Ontario

TORONTO - Ontario Power Generation is urging people to exercise extreme caution around rivers and lakes near hydroelectric stations and dams, especially in the north.

The giant utility says water levels and flows in northeastern river systems are already higher than normal for this time of year, and warns a heavy rain could cause them to rise in reservoirs and downstream of OPG facilities.

Most hydroelectric dams are remotely controlled by operators who are many kilometres away, and can be opened throughout the day, causing frequent and rapid changes to water flows and levels.

OPG warns these changing conditions create strong undertows, turbulence and sudden, powerful gushes in what had been calm-looking surface water.