A statement from the city of Leduc says 2,800 litres of diluted ethylene glycol leaked from its recreation centre into a storm water collection system.
The chemical is a moderately toxic, syrupy liquid used in antifreeze.
The town says a soccer ball struck and damaged an air purging valve on the recreation centre's roof Thursday, causing the leak.
Workers managed to clean some of the liquid with a vacuum truck before it reached an outfall.
The city says it's believed the spill is not hazardous to residents or wildlife but a barrier has been set up around nearby Telford Lake.
Provincial health and environment departments have been notified and are conducting water tests.