Mitigating flooding on the Gull River
Published July 7, 2016
The amount of snow, temperature, rainfall, frozen and saturated ground.
These are the factors that can contribute to high levels and flooding along the Gull River each spring.
Colin Clarke, a water management technician with Parks Canada and Jewel Cunningham, director of Ontario Waterways for Parks Canada, made a presentation to Minden Hills councillors June 30.
Flooding is common along the Gull River, which is part of the feeder system for the Trent Severn Waterway, during the spring freshet.
While there was flooding in Minden Hills township this spring, it wasn’t nearly as severe as the flooding that left parts of Minden underwater and the township in a state of emergency for three weeks in the spring of 2013.
Water from more than 20 lakes, 14 of them with dams operated by Parks Canada, makes it way through the heart of Minden via the Gull River before passing into Gull Lake and south through the feeder system.
“There are roughly 1,000 square kilometres of drainage area that comes through the town of Minden,” Clarke told councillors.
The dams, which use a system of stoplogs, have winter settings and water levels, as well as the amount of water in the snowpack, is monitored by TSW staff to determine if those settings need to be altered throughout the winter.
Automated weather monitoring equipment allows staff to access real-time time snow-water data.
If a winter season is short on snow, the reservoir lakes north of Minden are filled earlier.
“The goal is always to have the lakes full by the end of the spring,” Clarke said.
Factors such as temperature, ground that is still frozen, ground that is already saturated with water and rainfall all contribute to how high water levels get in the springtime.
“The timing matters, the temperature matters, there’s a whole bunch of different factors that come into play,” Clarke said.
Clarke said this spring, Kennisis Lake surpassed a century-old high-water reading.
“Our staff were up there every day, doing adjustments,” he said.
When drawdowns do take place, whether it be during dry periods or high-water periods, Parks Canada attempts to draw down evenly at each control point.
“We try to maintain that equal percentage,” Clarke said.
The federal government recently announced another $270 million for repairs and replacements of TSW infrastructure, in addition to $300 million announced last year.
Some $40 million of that new funding will be spent on dams in Haliburton County, including the complete replacement of the dam at Horseshoe Lake.
“We’ll have safe pedestrian access,” Cunningham said. “We’d like to make it more visitor friendly.”
The Horseshoe Lake dam is located near the Minden Wild Water Preserve. The project is scheduled to get underway this fall.
Clarke noted that the replacement of infrastructure would not change water management practises.
Reeve Brent Devolin said he thought there’d been “a very large cultural change” in the way Parks Canada and the MNRF relay water levels information to municipalities, with better communications and regular conference calls.
“We can prepare, we educate the public,” Devolin said.
Councillor Pam Sayne said that even with improved communication and evolving water management techniques, there were still homes that flooded this spring.
Clarke said the reality is there are some parts of Minden that are built on a natural flood plain.
“The areas that are in a flood plain, are still going to be in a flood plain,” he said.