The Town of The Blue Mountains would like to provide an update regarding the recent weather event that occurred on Monday, June 30, 2025.
Beginning around 4:00 p.m., the Town and surrounding areas experienced an extreme rainfall event, with Town Rain gauges measuring 85-125mm of rain recorded within a three-hour period. This event had a storm frequency greater than a 1 in 500-year event, according to the Grey Sauble Conservation Authority. The level of precipitation led to runoff levels in local waterways that exceeded typical spring levels, which is uncommon for this time of the year.
Due to the rapid intensity and volume of the rainfall, the Town’s stormwater management and drainage systems were overwhelmed. While all municipal wastewater treatment plants remained operational, the stormwater infrastructure was unable to manage the high levels of runoff. Overland flow led to localized flooding and submerged maintenance holes, which caused additional water to enter the wastewater system.
As a result, two wastewater bypass and overflow events occurred. One occurred at the Mill Street Pumping Station and the other at a maintenance hole near the western end of Cottage Avenue, with overflows discharged into the Beaver River. The overflow at the Mill Street Pumping Station ended on July 1 at 1:55 a.m., while the surcharge at Cottage Avenue ended on June 30 at 9:35 p.m. The Town’s drinking water was not impacted. Samples were collected during the event and hand-delivered by Town staff to SGS Canada on July 1, 2025, for testing.
Flooding and submerged roads occurred throughout several areas of the municipality, including a stretch of Highway 26 between Mill Street and McAuley Street. Upcoming improvements on Elgin Street are expected to help relieve some of the pressure on this area of the system. Planned work related to the Bay Street East Reconstruction project, which includes updates to the Mill Street Sewage Pumping Station and the installation of a secondary force main through Bay Street, will also increase the Town’s ability to manage future heavy rainfall events. In addition to these projects, the Town is actively working on a comprehensive Drainage Master Plan to provide a long-term strategy for managing stormwater in both existing and future growth areas. The plan will identify drainage deficiencies, address flood risks, enhance public safety and improve maintenance over the long term.
The intense rainfall also caused a culvert failure along Duncan Street, leading to the washout of a section of roadway. As a result, Duncan Street West is currently closed between Victoria Street South and 90 Duncan Street West until repair works are completed by the Roads Division. This work is scheduled to begin the week of July 7, and motorists and pedestrians are advised to use caution, follow posted detours and be mindful of crews working in the area.
During and following the rainfall, Town Staff, including Wastewater, Roads, the Fire Department and Community Services actively responded to mitigate damage and maintain public safety. The Wastewater division coordinated with three local contractors to assist with emergency pumping at key locations across Town. In addition, the Ontario Provincial Police (OPP) were on-site monitoring road conditions.
While this storm created challenges in both volume and intensity, the Town is committed to strengthening critical infrastructure and continuing to improve the resilience of stormwater systems to adequately handle more frequent extreme weather.
For more information, please contact:
Town of The Blue Mountains
Operations Department
(519) 599-3131 ext. 276