Keeping lake levels up through dry summer
By Jenn Watt
Sept. 13, 2016
Spring and summer of 2016 presented particularly difficult weather conditions for the staff at Parks Canada as they grappled with management of the Trent Severn Waterway and the lakes that feed the system.
A surprisingly wet March followed by the driest summer in recent history required an innovative approach to managing the water.
At their meeting on Saturday at Haliburton’s fish hatchery, members of the Coalition for Equitable Water Flow praised the staff managing the complex system and noted that extreme weather was becoming the norm.
Ted Spence, chairman of CEWF’s executive committee, said 2016 offered up “one of the most incredible situations we’ve ever faced.”
“In the spring, there was a relatively warm winter, relatively limited snowpack and in the first week of March we posted to our website that Trent Severn had started to replace logs in our dams and we were happy. It seemed the right thing to do,” said Spence.
The lakes began to fill up, but then over the course of eight days in March five inches of rain fell. Lake levels went up “in most cases, with ice still in place,” he said.
CEWF has been gathering reports of damage from that ice to give to TSW management for their records, executive member Bruce McClennan said, though the group does not fault staff.
According to acting water management engineer Colin Clarke, the town of Minden was top of mind throughout the spring. Regular communication between Minden Hills and Parks Canada as well as the Ministry of Natural Resources and Forestry helped as the decision was made to keep many lakes and the Gull River that flows through town as high as possible to avoid flooding.
As the region went from high water to drought, TSW management had to change gears, limiting flow on lakes and reducing the flow through the Otonabee River in Peterborough County.
“By May 31, we had pushed to absolute minimum flow on the Otonabee River,” Clarke told the group.
Knowing very little rain was coming, Clarke said it was decided the reservoir lakes in the Haliburton County region needed to be kept as full as possible.
“We were basically keeping the Kawarthas high, or letting the rain water sit in there every time it did rain, in order to reduce the amount flow we needed from the Haliburton lakes. That was the strategy,” he said.
The strategy worked.
“The late spring and summer, which is actually been about the driest period that most of us have ever experienced, and yet most of our members looking out the front door of their cottage think it’s been a normal year. And it’s been anything but normal, but what we’ve seen on our lakes has been much closer to normal than we might have imagined was possible,” Spence said.
According to figures presented at the meeting, between May 1 and Aug. 12, in Haliburton 178.2 mm of rain fell, 59 per cent of what normal precipitation (304.1 mm) for that time period would be.
Peterborough and Trenton were worse off, receiving 31 per cent and 40 per cent of normal rain respectively.
“The Weather Network said that total for the middle of August represented the driest May to August period since 1914. That’s 102 years since the last time it was that dry,” Spence said of the Peterborough region.
“I just want to emphasize how significant the shortfall was in terms of water resources,” he said.
Just as conditions were reaching a breaking point in early August and a drastic drawing down the reservoir lakes seemed unavoidable – triggering public notices that lake levels were about to drop substantially – the whole region received a wallop of rain.
While precipitation levels were extremely low up to Aug. 12, when figures are adjusted to capture precipitation to Aug. 31, Haliburton ended up receiving 99 per cent of normal rainfall with 338.6 mm. (Peterborough did not fare as well, with 40 per cent of normal precipitation. Trent received 67 per cent of normal.)
Jewel Cunningham, director of Ontario Waterways at Parks Canada, told the group that the government had been shifting to more science based decision making for the TSW, which has helped in managing water levels. She highlighted millions of dollars from the federal government to repair, and in some cases replace, infrastructure throughout the waterway.
Dam safety was also raised by Clarke, who said he’d seen photos of people tubing and paddling around dams and jumping off bridges or playing in the splash of a spillway. He asked the group to remind their members of the danger the dams pose should someone fall in.
CEWF has 32 member lakes, representing 91 per cent of the reservoir lake capacity, and some 35,000 shoreline property owners. Since their formation in 2006, the group has worked on improving communications with the government and management of the TSW, advocating for a water management approach that takes all portions of the massive navigation system into consideration. Recently, the CEWF joined with local municipalities to create the Upper Trent Water Management Project, which met for the first time in June.