From the Dayton Daily News:

The toxic blue-green algae choking Ohio’s largest inland lake is part of a much wider farm pollution problem that a state official says must be addressed…

…Farm pollution, including manure, herbicides and pesticides, affects waterways from Lake Erie to the Ohio River and nationwide from the Chesapeake Bay to the Gulf of Mexico, the newspaper said.

"It’s a problem we can no longer ignore," said Robert Boggs, director of the Ohio Department of Agriculture. "We have to be very aggressive and assertive in our way of handling it." …

No state or federal laws limit how much manure, fertilizers or pesticides can wash off Ohio farms during storms, the newspaper said.

In Mercer County, where Grand Lake St. Marys is located, the number of cows, hogs and chickens has more than doubled in 20 years and the 9.7 million animals produce more than 1.6 million tons of manure each year, according to The Dispatch’s analysis of U.S. Department of Agriculture statistics.

Much of that manure is spread on crop fields and some is washed into streams, many of which feed Grand Lake St. Marys.

Sean Logan, director of the Ohio Department of Natural Resources, says it’s much more difficult to track farm pollution than to trace water pollution to a factory.

"Could you imagine trying to determine which farm and which field is contributing what percentage to the problem?" he said.

State officials say more area farmers are applying for voluntary, federally funded programs paying them to reduce runoff. About 30 percent of farms in the Grand Lake St. Marys area are involved in at least one of those programs.

Critics have said the voluntary programs aren’t enough and environmental advocacy groups say the government does not hold agriculture responsible for its pollution. But farmers and agriculture-advocacy groups argue that they have a vested interest in protecting their land and water.

No farmer wants expensive fertilizer washing from fields into streams, said Larry Antosch, the Ohio Farm Bureau Federation’s environmental policy director.

The state is beginning to mandate some of these farm practices, and the Department of Natural Resources will require most Grand Lake St. Marys-area farmers to test their soils and create plans to manage manure.