“Algal blooms and dead zones in Lake Erie were severe during the 1960s, caused primarily by large releases of phosphorus from sewage and industrial plants. The 1972 federal Clean Water Act and the 1978 bi-national Great Lakes Water Quality Agreement led to dramatic reductions in phosphorus from these sources and a rapid improvement in water quality.

Lake Erie, however, saw a reemergence of the algal blooms and the growth of the dead zone in the mid-1990s, and the problems are worsening. In 2011, for example, Lake Erie experienced its most severe bloom of toxic algae on record. Last fall a toxic algal bloom in the lake forced officials to shut off a public water supply system in Ohio.

The new studies, part of the Ecological Forecasting (EcoFore) Lake Erie project led by researchers at the University of Michigan, found that the current targets to reduce phosphorus to alleviate algal blooms in Lake Erie may not be low enough to revive the dead zone. That conclusion informed the International Joint Commission’s recommendations in February for improving Lake Erie’s water quality.

The findings, and those of other studies from across the Great Lakes region, are delivering an ever clearer picture of the specific causes of nonpoint phosphorus runoff, algal blooms, and dead zones. The basic drivers of these problems are no longer unknown. The new research fills a critical void in information that has been often cited as a reason that strict regulations on nonpoint pollution sources, including agriculture, were not regulated under the 1972 federal Clean Water Act.”