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High water levels at Manasan could result in rapid rise of Burntwood River downstream

Manitoba Hydro is warning Thompson residents and businesses to be prepared for water level rises of up to three feet in the course of a day because water levels behind the Manasan Control Structure are near the maximum operating limit.

Manitoba Hydro is warning Thompson residents and businesses to be prepared for water level rises of up to three feet in the course of a day because water levels behind the Manasan Control Structure are near the maximum operating limit.

Water levels at the Manasan Control Structure upstream of the city have reached 649 feet above sea level as a result of melting snow. If it reaches its maximum normal operating limit the structure's emergency fuse plug, which provides an additional passage for water to flow through it, goes into operation. The fuse plug activates under high water flows to prevent damage to the rest of the structure and once the water overtops it, the fuse plug erodes in several hours, lowering water levels behind the structure and potentially causing rises of one to three feet in the water level downstream.

"We are currently monitoring the situation very carefully," said Manitoba Hydro  corporate communications director Scott Powell in a May 11 news release. "At this stage we are not anticipating an issue, but we believe it is prudent to notify all residents in the Thompson area of the possibility of this rapid rise in water levels along the river."

Manitoba Hydro has reduced outflows from the Notigi Control Structure to reduce the amount of water entering the Burntwood River from the Churchill River Diversion and reduce stress on the Manasan Control Structure, which is eight kilometres upstream of Thompson and helps provide stable ice over on the river to prevent ice jamming and associated problems in the area and provide adequate water discharge during times of high water flows. Major precipitation could further increase water levels, though the five-day weather forecast does not currently include significant rain.

"We are currently placing sandbags on top of the fuse plug simply to provide some additional reinforcement of the structure," said Powell. "Thanks to flow reductions at Notigi, water levels are stabilizing, and we just want to ensure we have no seepage or other issues at Manasan caused by levels being so close to the maximum operations limit."

Manitoba Hydro has informed RCMP and emergency officials in Thompson of the status of water levels and flows at the Manasan Control Structure as a precaution.

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