TRAVERSE CITY, Mich. – The U.S. and Canada should crack down on sources of phosphorus runoff blamed for a rash of harmful algae blooms on Lake Erie, an advisory agency said Thursday.
The algae produce harmful toxins and contribute to oxygen-deprived dead zones where fish cannot survive.
The International Joint Commission said in a report that urgent steps are needed to curb runaway algae – a problem that led both nations to reach their first agreement to improve Great Lakes water quality more than 40 years ago, when some considered Erie ecologically dead.
Tougher standards for municipal and industrial waste treatment produced improvements by reducing the flow into the lake of phosphorus on which algae feeds. But the problem began worsening in the late 1990s. In 2011, the largest mass on record formed in the lake’s western basin, eventually reaching more than 100 miles from Toledo to Cleveland.
The report says different sources of phosphorus runoff have emerged – primarily large farms, where manure and other fertilizers are washed into tributary rivers during storms and snowmelt. They accounted for more than half of the phosphorus that reached the lake in 2011, while one-third came from smaller farms and nearshore communities as well as city sewers.