The Town of Stonewall is reviewing its drainage infrastructure and emergency response following the historic June 9 rainfall event, while emphasizing that the community’s systems performed well despite being tested by an unprecedented volume of water.
The storm dropped approximately 255 millimetres of rain on the community in a matter of hours — an event Town CAO Dennis “Wally” Melnyk described as roughly a one-in-25,000-year rainfall event.
“The June 9th rainfall was extraordinary in both intensity and volume,” Melnyk said. “At approximately 255 mm, it represents what would be considered a one in 25,000-year event. Given the magnitude of this storm, our existing infrastructure performed very well overall.”
While the Town avoided widespread infrastructure failures, the overwhelming amount of water entering the drainage system in a short period created significant challenges.
“The most significant challenges we experienced were related to the sheer volume of water entering the system in an extremely short period of time,” Melnyk said. “During peak flow conditions, some drainage infrastructure — such as localized culverts, ditches and low-lying collection points — was temporarily overwhelmed.”
He noted these issues reflected capacity exceedances during an extreme weather event rather than failures of the infrastructure itself.
“Importantly, we did not observe widespread structural failures, but rather capacity exceedances under extreme conditions,” he said.
Although portions of Stonewall’s drainage network date back several decades, Melnyk said the Town has an ongoing program to assess and upgrade infrastructure through its asset management plan.
“The Town operates under a comprehensive asset management plan that includes a robust infrastructure review and investment program,” he said. “While some components of our drainage network date back decades, they are regularly assessed and prioritized for upgrades based on condition, risk and growth needs.”
He added that infrastructure improvements must be balanced with affordability and the Town’s long-term financial sustainability.
Looking ahead, the municipality plans to conduct a detailed review of the storm response to identify opportunities for targeted improvements.
“We fully expect that lessons learned from the June 9th storm will inform future infrastructure design, prioritization and policy decisions,” Melnyk said.
However, he cautioned that no municipal drainage system can reasonably be designed to handle rainfall events of this magnitude.
“It is important for residents to understand that municipal systems are not designed to accommodate rainfall events with a probability as low as 0.004 per cent,” he said. “Designing for that level of extreme would require an extraordinary level of investment that is not financially sustainable for a community of our size.”
The Town has not yet determined the full cost of repairs or potential drainage improvements, as assessments remain underway.
“At this time, we do not have finalized cost estimates for repairs or potential system enhancements, as assessments are ongoing,” Melnyk said. “Any future capital investments will be considered through our established planning and budgeting processes.”
The June 9-10 storm brought record rainfall to Stonewall and surrounding communities, causing widespread basement flooding, road closures, drainage issues and states of local emergency across several municipalities in the Interlake.
