River flow high but within normal range

This year’s spring runoff along the Mad River was at the high end of the typical range, but not a historically significant flooding event, according to Laura Wensink of the Nottawasaga Valley Conservation Authority. In fact, water levels were higher in the spring of 2025, as measured by the Environment Canada gauge at Airport Road. This spring, an ice jam, approximately 1.5 km upstream of Carruthers Memorial Park in Avening diverted the river’s flow through the channel floodplain and adjacent agricultural fields and forested areas.

There is visible damage within Carruthers Park, including a large hole, approximately four feet deep just behind the picnic pavilion. The entire area is strewn with river rock, indicating the path the river took during spring runoff. A graduate student from University of Guelph measured volumes at four cubic metres per second at the height of the flow.

Last year, the NVCA undertook a bank stabilization project in the park including construction of a side channel to handle excess flow. About 10 metres of the 80-metre bank stabilization project washed away in this year’s runoff, but according to Don Little, NVCA manager of stewardship and restoration services, the remaining 70 feet fared quite well.

“We design these habitat features to resist the water in the natural state of the stream. It’s hard to predict exactly where the water is going to come from,” he said. “In this case, the ice jam diverted the flow across an agricultural field, and through the middle of the park.”

Wensink says the damage in the park is a powerful illustration of the importance of flood plain mapping and prohibiting development close to the river.

Geomorphology consultant Paul Villard says, “A defined pathway has now formed through the agricultural field and across the park floodplain. Essentially, the erosion marks the beginning of a channel, with multiple scour pools and points that have developed both within the park and farmland. Several of these scour features are quite deep. For flows to reoccupy this route, discharge would probably need to exceed bankfull conditions.

“There is a notable accumulation of sand, gravel, and cobble (within the park). Removal is unnecessary, as the materials are alluvial and are expected to reposition and settle naturally over time.”

It is expected that repairing the affected areas will be fairly straightforward, and will include replanting of disturbed areas. Overall, the impacts are considered to be localized and manageable.

Little says the NVCA is currently figuring out cost and timing of next steps. “We will be in the park, repairing the damage as soon as we possibly can,” he said.

Bonnie MacPherson photo: An ice dam upstream of Carruthers Park in Avening caused the Mad River to breach its banks and flood the park causing significant damage.