Officials in Kalamazoo say a clogged sewer may have gone unnoticed for days, leading to a roughly 60,000-gallon overflow.
The city is advising people to avoid coming into contact with water at the north end of Monarch Millpond and Portage Creek following the problem, which was reported Thursday morning.
The city says the overflow from a manhole may have started as early as Monday.
Workers removed a blockage Thursday afternoon and normal flow conditions were restored to the sewer.
Still, people are urged for now not to swim, wade, fish, canoe or kayak in the water.
Officials say pets and children also should be kept from the area.