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Regulation prevents flooding on Lake Winnipeg

Lake Winnipeg is five feet (1.5 metres) higher than it was last year.

Heavy rainfall in April and May and the melting of winter’s thick snowpack has swelled the lake to rival record flood years in 1974 and 1966.

In both those years lakeside communities like Riverton, Gimli, Sandy Hook, Winnipeg Beach, Dunnottar, Grand Beach, and Victoria Beach saw damaging flooding during high-wind events.

Lake Winnipeg is forecast to peak at about 717.2 feet above sea level in late July, nudging closely to the level it reached in 1966 (717.6 feet).

The big difference from 1966 to 2022 is Lake Winnipeg Regulation.

Lake Winnipeg Regulation (LWR) was developed by Manitoba Hydro to achieve two key objectives: reduce shoreline flooding on Lake Winnipeg and support hydroelectric generation on the Nelson River to meet Manitoba’s growing energy demand. LWR began operating in 1976.

As part of LWR, Manitoba Hydro built a second outlet at the north end of Lake Winnipeg to move water out of it more effectively. With the Jenpeg Generating Station and control structure, it’s resulted in up to 50 per cent more water flowing out of the lake than would otherwise flow out naturally.

By increasing the lake’s outflow, more water can be passed out of the lake in high-water years like 2022, reducing the risk for severe flooding as seen in the 60s and 70s by keeping flood peaks about two feet lower.

Water levels on the Nelson River downstream of Jenpeg are also increasing and will be high all summer. Manitoba Hydro is working with communities that may be affected by the increase in water flows.

Common misconception

Many people think Manitoba Hydro always keeps the lake at higher-than-normal levels for power production.

That’s not the purpose of LWR. The LWR project was not built with the intent to hold water in Lake Winnipeg. Rather, it was designed to move more water out – helping to reduce flood risk around the lake and to ensure a reliable water flow for electricity throughout the year.

How LWR works:

  • Manitoba Hydro is required by its provincial license to set the outflows from the Lake Winnipeg when the water level of the lake is between 711 and 715 feet above sea level.
  • As seen this summer, when the level is above 715 feet, Manitoba Hydro must operate the control structure at Jenpeg until the water level of Lake Winnipeg falls to 715 feet. (Manitoba Hydro increased outflows from the lake earlier this spring.)
  • When the level is below 711 feet, Manitoba Hydro must operate the control structure at Jenpeg to ensure a reliable supply of electricity production.

Lake Winnipeg still follows a typical seasonal pattern of rising in the summer and falling through the winter.

Historical records show that the daily average water levels since LWR began in 1976 are just over an inch different than the daily average levels prior.

See more information on Lake Winnipeg Regulation.