Toxic algae covers river in foamy slime near Wisconsin’s capital

MADISON, Wis. — Residents of Madison, WI were shocked to see their local waterway turned into a river of toxic, foamy slime Friday.

A giant blue-green algae bloom was flowing down the entire length of downtown Madison in Lake Mendota and the Yahara River. The city warned residents it’s highly toxic.

Scientists say humans and mother nature are to blame for the bloom, which was caused by the spring’s hot weather combined with increased phosphate run-off. Officials with the Clean Lakes Alliance say just one pound of phosphorus in runoff can produce 500 pounds of algae.

Bikers along the Yahara River said it looks like suds spewing out of a washing machine.