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Snow surveys help OPG’s hydro operations prepare for freshet

Once the calendar flips over to March, OPG’s Alain Ratthe gets out his snow shoes, packs his winter gear, and heads into the bush in northeast Ontario to get a read on the snow.

An employee performing a snow survey.
An OPG employee performs a snow survey.

Ratthe, a Service Trades Maintainer in OPG’s Timmins Production Group, works with partner Ed Smart to conduct bi-weekly snow surveys at fixed sampling locations, using tools to measure snow depth and density. Similar surveys are performed across OPG’s hydro regions at this time of year.

It’s one of the early efforts to help the company’s hydro operations prepare for the coming spring freshet, the influx of water into the province’s river systems from spring rains and melted snow.

Data collected from these snow surveys, along with data from similar surveys conducted by the Ministry of Natural Resources, weather forecasts, and satellite-derived snow cover maps, help OPG’s water managers estimate the spring runoff potential and assist with freshet planning at OPG’s hydro stations and water control structures.

“We will be in the bush every two weeks at four different locations in the region until the snow is entirely gone,” Ratthe said.

To get an accurate read of snow conditions in the northeast, he and his partner will drive a fair distance to reach sampling areas in the east and west sides of the region, where the Abitibi River and Mattagami River watersheds are located.

OPG's Alain Ratthe and partner Ed Smart head into the bush in snow shoes to conduct a snow survey.
OPG's Alain Ratthe and partner Ed Smart head into the bush in snow shoes to conduct a snow survey.

When Ratthe visits a sampling location, he uses a special aluminum tube with teeth on one end to cut and extract a core of snow from the snow pack. The snow, which is compounded inside the tube, is then measured and weighed on a digital scale.

“Depending on the weight of the snow, that will tell us the water content inside the snow, which gives our water managers a good idea of how much water to expect once everything starts to melt and the water reaches the watershed,” Ratthe explained.

But snow in the bush does not necessarily equal water in the river system.

“Snow usually only accounts for a fraction of the water that ends up in river systems and lakes in the spring,” said Kurt Kornelsen, Senior Manager of Water Resources at OPG.

OPG's Alain Ratthe and Ed Smart weigh a snow sample using a digital scale.
OPG's Alain Ratthe and Ed Smart weigh a snow sample using a digital scale.

Periods of sunny weather with warm winds may cause considerable amounts of snow to evaporate directly into the atmosphere, rather than melt and enter rivers.

On the flip side, sudden warming and spring rainfall can quickly melt the snow and significantly increase the water available in the watershed.

OPG’s water management staff take into consideration all of these factors to predict the coming freshet and determine appropriate strategies, including how much water to drawdown from key reservoirs to accommodate higher flows.

To learn more about how OPG prepares for freshet, visit opg.com/water.