OPG April 6th Update on Water Conditions

Here is the latest information from Ontario Power Generation (OPG)regarding conditions on regulated lakes and rivers in Northeastern Ontario.

Reservoirs have been drawn down in anticipation of normal to above normal precipitation in the coming weeks. At this time, OPG feels there is sufficient storage available to mitigate the risk of flooding - our primary reason for drawing down reservoirs. The drawdown of area reservoirs by OPG is essentially complete. This does not mean that all dams are completely "closed" off. Some control dams and generating stations have minimum flow requirements identified in the river system's water management plan which require OPG to pass a minimum amount of water at all times (may vary from 3cms to 15cms, depending on the facility). These flow requirements exist for various reasons which can include providing drinking water downstream, providing water for hydroelectric generation to other dam owners or diluting effluent from industrial operations such as mining and forestry.

Other dams also have minimum flow requirements and maximum flow constraints to protect the walleye spawn downstream. Those constraints will be triggered once the water reaches a temperature of 5 degrees Celsius.

Snow surveys completed March 30th and 31st by Ontario Power Generation, the Ministry of Natural Resources and the Mattagami Region Conservation Authority on the Upper Mattagami watershed are showing water content to be between 38% and 77% of normal for this time of year. Snow surveys completed on April 1st on the Matabitchuan and Montreal River systems registered water content at between 42% and 136% of normal. Last year, at this time, there was virtually no snow recorded at any of the snow survey stations.

The majority of inflows required to fill area reservoirs comes in the form of spring precipitation. The extra snow this year will undoubtedly help, however, the determining factor in filling reservoirs in time for Victoria Day weekend remains April and May showers. With that being said, OPG continues to anticipate that summer minimum elevations will be reached in time for Victoria Day weekend, as per the requirements identified in approved and draft water management plans.

In spite of warmer temperatures, night time lows continue to drop below zero, essentially freezing and trapping the water that thaws earlier in the day. As temperatures begin rise in the coming weeks and night time lows start to hover above the freezing mark, inflows will begin to increase and water levels will begin to slowly rise as the runoff makes its way into the watershed. This process will accelerate once spring showers begin as there is no vegetation to absorb the precipitation.

Ice is slowly melting on area lakes and rivers. Conditions around hydroelectric dams and stations are dangerous, especially at this time of year. Fast moving water means thinner ice around dams and stations.

For your own safety, please avoid these areas. Stay Clear, Stay Safe!

I will provide another update in approximately two weeks.

Marcel Pelchat
Public Affairs Officer
Ontario Power Generation