The kind of toxic algae that forms each summer on Lake Erie and other lakes around Ohio feeds on phosphorus, a key element of livestock manure and sewage. Much of the phosphorus that gets into the lake comes from the Maumee River, which flows through eastern Indiana and western Ohio, depositing its waters into the western part of Lake Erie near Toledo.
Manure and sewage wash from soil and into the rivers and streams that feed the Maumee. More rains mean more runoff.