Janet Davis, the former city councillor for the area, was tagged in Sarty's tweet. She responded, saying city inspectors had been notified and were at the scene.

Stephen Wickens, who lives near Danforth and Coxwell avenues, said he was riding his bike down in the ravine system between Cullen Bryant Park and the Don Valley Parkway in the early afternoon on Thursday.

"The creek water often looks cloudy, but today was a more intense greenish grey and it smell[ed] sort of like lawn fertilizer," he told CBC Toronto in a Twitter message.