Water levels at Chestermere Reservoir returned to normal on Monday, July 27, 2026, after a three-day response and recovery effort sparked by an oil spill upstream in Calgary.
The Western Irrigation District shut off the flow into the reservoir on Friday, July 24, after staff spotted an oily sheen on the Western Headworks Canal. The contamination was traced to a commercial business in southeast Calgary, where a storage tank failed and released about 1,200 litres of motor oil and hydraulic oil into the city’s stormwater system.
A coordinated response involving the City of Calgary, Alberta Agriculture and Irrigation, and the irrigation district quickly contained the spill. The Calgary Fire Department used a vacuum truck to remove the oil from the canal, and the cleanup was completed within 24 hours.
WID reopened the inlet on Saturday, July 25, around noon. Because of high demand and reduced flow, water levels in the reservoir dropped about 33 centimetres before the district was able to boost the inlet flow on Sunday. Normal levels were restored by noon on Monday.
Throughout the incident, water delivery to the district’s farmers and agricultural clients was never interrupted. The business responsible is covering all cleanup costs, and no lasting environmental damage is expected.
The Chestermere Lake and Watershed Advisory Committee, a city subcommittee, monitors the lake’s ecosystem for threats like this one. The quick containment shows how seriously local agencies take the health of the reservoir and the surrounding watershed.
