With wide swings in temperature and precipitation, conservation authority officials on each end of the Thames River continue to keep an eye on conditions this winter -- and what it might mean for the spring.
With wide swings in temperature and precipitation, conservation authority officials on each end of the Thames River continue to keep an eye on conditions this winter – and what it might mean for the spring.
Southwestern Ontario has experienced a relatively mild season overall, including a few heavy downpours that led to the melting of snowpacks and some localized flooding within area watersheds last month.
Jason Wintermute, manager of watershed and information services for the Lower Thames Conservation Authority, said the diminished snowfall itself isn’t that uncommon.
“From the perspective of the lower Thames, the lack of snow is not unusual,” he said Thursday. “The lack of ice on the river and lakes I would say is unusual.”
Wintermute said the Chatham-Kent area often has all of its snow melt out several times over the course of a winter.
“How much water is stored in the snow in the upper Thames” will be the deciding factor on potential later impacts on river flows, he added.
Eleanor Heagy, communications specialist for the Upper Thames Conservation Authority, said there is some snow cover, although noticeably less than the long-term average in that end of the watershed.
She said it’s still to be determined what that will mean in the coming months.
“Last fall was relatively wet, and the winter so far has also been relatively wet, so the ground is saturated and/or frozen,” she said. “This is relevant because it increases the likelihood of runoff when we do have snow melt and/or rain because the ground can’t absorb more water. As usual, it all depends on the weather.”
As far as water quality, Heagy said the non-growing season is when most nutrients are picked up in runoff from agricultural lands.
“The more winter melts we have, the more nutrients are being delivered into waterways,” she said. “These nutrients feed summertime algae blooms if the weather conditions are right.”
The upper and lower Thames watersheds have experienced multiple flood watches and warnings – along with localized states of emergency – in recent months, largely because of the water levels of the rivers and lakes.
Wintermute said the lack of snow leads to lower peak flows during the spring melt, which is “generally better from a flooding perspective.”
However, this can also come with other tradeoffs.
“It also means less water to sustain flows throughout the spring when wildlife is expecting it for their lifecycle processes,” he said, adding that jurisdictions needing to fill reservoirs with the spring meltwater can be affected.
Last winter, the lower Thames experienced an ice jam situation at the mouth, causing a drastic rise in levels and a tense situation as municipal and conservation officials kept vigil along the dikes.
This season’s lack of ice has allowed for the possibility of further erosion over the winter when the river and Lake Erie would have been locked up with ice, Wintermute said.
“With no ice on the river, nor on the lake, we are not concerned about ice jams,” he said. “Based on the weather forecasts, it doesn’t look like we can now get any substantial amount of ice on the river to worry about.
“That being said, the flood protection works downstream were stressed quite a bit from the ice jam last year.”
Necessary repairs have already been taken care of, Wintermute added, but medium- to long-term work is still needed to “bolster their effectiveness.”
He said federal funding that the municipality received will help go towards the cause.