A new federal report says Ohio cities are just as much to blame as its farms for toxic algae polluting Lake Erie.

The Columbus Dispatch reported that a U.S. Geological Survey study found sewage plants in Detroit, Toledo and other lakeside cities contribute just as much phosphorus to the lake as manure and fertilizer runoff from farms.

Phosphorus is a byproduct of sewage, fertilizers and manure and is responsible for the toxic blue-green algae that excrete liver and nerve toxins which can sicken people and kill fish and wildlife.

The algae threaten Lake Erie’s $10 billion-a-year fishing and tourism industry. Algae can cause "dead zones" in bodies of water where no oxygen exists, making them uninhabitable.

The current bloom of algae in Lake Erie has caused public beaches in at Maumee Bay and Kelley’s Island to issue health warnings.

Ohio-based scientists previously thought that farm runoff was responsible for as much as 60 percent of phosphorus in Lake Erie.

"There are some major discrepancies from these modeled results and what we’ve measured," Peter Richards told the newspaper. Richards is a water-quality researcher at Heidelberg University’s National Center for Water Quality Research.

However, Geological Survey research hydrologist Dale Robertson said he stands by his computer modeling, which shows that sewage plant cleanup ordered by the government in the 1980s didn’t cut enough phosphorous.

Heidelberg’s data show that the Maumee River is the leading supplier of phosphorous into Lake Erie, with 82.6 percent of it coming from farms.

The No. 2 source is the Detroit River, with nearly 75 percent coming from sewage-treatment plants.

Overall, 42.1 percent of Lake Erie’s phosphorous comes from sewage, with 43.6 coming from farms. The rest comes from decaying plant matter in forests and lawn fertilizer that gets washed into storm sewers.

Sandy Bihn of the Toledo-based Lake Erie Waterkeeper group said officials should order further phosphorous cuts at Detroit’s sewage treatment plant.

The Ohio Farm Bureau Federation’s Larry Antosch had a similar reaction. The federation has long said that farms are not solely to blame for algae in Ohio’s lakes and ponds.

By the Associated Press