Lack of snow could lead to summer drought, conservation authority warns

One of the main conservation authorities in the Ottawa area is concerned a lack of snow this winter could lead to drought in the summer.

According to Environment Canada, Ottawa has seen 96.7 centimetres of winter precipitation like snow and ice pellets since Dec. 1.

Over the same timeframe last year, Ottawa saw 244.5 centimetres. That's put those who monitor the Rideau Valley watershed's conditions on alert.

"We're always worried that the water levels are going to get too high and cause flooding," said Brian Stratton, manager of engineering services for the Rideau Valley Conservation Authority.

"But there's also the other extreme, [that] they hardly raise at all. And that's a scenario this year."

Snow melt happening earlier

Normally, Stratton said, the spring freshet — the period when the snow melts and runs into rivers — begins in the middle of March, with peak flow happening from the end of March into early April.

It's been happening earlier and earlier over the past couple of years, Stratton said, and this year it appears to be already taking place.

With minimal snow on the ground and warm weather slated this week, the region could be entering March with no snowpack — something that has Stratton worried about drought.

"We don't know that right now, but all signs indicate that could happen," he said. "Because we're going to go in with limited precipitation and limited soil moisture, et cetera, as we enter spring."

Flooding on the Rideau River in 2017. (Roger Dubois/CBC)

It's too early to make a firm prediction, Stratton said, as there could be another snow dump before winter is out, plus more rain in the spring.

Over the past two decades, there have been drought years half the time, Stratton said.

While their severity varies, droughts do have implications for agriculture and aquatic life, he said. But Ottawa doesn't have to worry about its drinking water, as the source from the Ottawa River is plentiful, Stratton said.

The same goes for people on private wells, Stratton said. But an extended drought over many years could lead to a lower water table, he warned.

Lack of snow can damage soil, expert says

Another concern with limited snow is the potential impact on soil, as snow provides nitrogen.

"[It's what] plants need to grow and to photosynthesize and operate," said Ed Gregorich, a retired scientist with Agriculture Canada.

This year, Ottawa has experienced many snow melts, and that means the nitrogen the snow carries is lost to runoff, Gregorich said.

Even though snow only provides about five per cent of what a farmer would put on their fields with fertilizer, Gregorich said it's still the case that the more snow, the better.

"For an agricultural soil, the farmer can manage that. It's the natural ecosystems where this might have an effect," he said.

"[Without that nitrogen] the forests become more nutrient-poor."

Ed Gregorich, a retired soil scientist with Agriculture Canada, says a shortage of nutrients that would normally be provided by snow can take a toll on plants. (Francis Ferland/CBC)

Gregorich said he never thought he'd see the weather changes that have happened over the last five to 10 years, including extreme thaw-freeze cycles, which bring their own concerns.

"The system that we are in right now, with warming and less snowfall and more extreme events, is causing a disruption to the whole cycle that we're used to — you know, that we've been living with for forever," he said.

Scientists are just now understanding how natural processes are being effected by those changes, Gregorich said, and the next step will be learning how to mitigate them.