Glenmore Reservoir water level lowered to make room for spring runoff

The city has begun lowering the water level of the Glenmore Reservoir to make room for the annual spring runoff from the Rocky Mountains, which in turn is causing the Elbow River to rise.

Frank Frigo with the City of Calgary says precipitation in the Bow and Elbow river basins has been well above normal in recent months.

While that's not an indicator of what's to come, he says Calgarians should know conditions on rivers and creeks can change rapidly.

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"Because we have steep mountain terrain upstream, we have very limited time to respond," he said. "The flood mechanism in Calgary is very different from the flood mechanism in other jurisdictions, for instance Winnipeg, where the warning time can be up to a month."

The warning comes as flood season arrives, which generally runs from about May 15 to July 15 each year.

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Rain, more than snow, is what generally causes flooding, said Frigo.

"Even during 2013, snow represents only about 10 or so per cent of the flood generation potential," he said. "The snow melt mechanism is much slower than the rainfall mechanism."

Between mid-May and mid-July, major rainstorms can trigger flooding quickly.

The city is still working on several flood mitigation projects along its rivers and the province has an arrangement with TransAlta to lower the levels on the Ghost dam, which is upstream of Calgary on the Bow River.

Frigo says information on flood preparation can be found on the city's website.