A first-of-its-kind study says Iowa's lakes are dirtier now than they were before farming and development arrived.
The study by Iowa State University scientist John Downing and others is likely to figure heavily into future debates over farm regulations.
Downing says he was shocked at how much more silt is running into Iowa waterways now, even after decades of work to ease the flow.
The study found that lake conditions vary widely, but of the 33 natural lakes sampled, 88 percent gained phosphorus over the past century-and-a-half. Phosphorus is a naturally occurring element used in crop and lawn fertilizers and it feeds algae blooms that kill fish and cause bacteria outbreaks.