Federal environmental regulators must make "radical change" to the U.S. storm water program to clean up the nation's water and reverse degradation, a new report says.

The report by the National Research Council highlights the problem of combined sewage systems that attempt to dispose of both rainwater and waste. In most cities, those systems are reaching capacity, causing increasing amounts of rainwater to flow across urban landscapes—picking up pollutants from garbage to toxic chemicals—and into streams, lakes and rivers. That runoff pollutes watersheds and causes erosion

The council recommends that the U.S. Environmental Protection Agency, which regulates storm water discharged by cities, shift its focus from chemical pollutants in storm water to the runoff problem. The EPA commissioned the report.

"All storm water and other wastewater discharge permits should be based on watershed boundaries instead of political boundaries," the council says in a press release.

The report notes storm water-control measures including land conservation, reducing roads, parking lots and other hard surface covers (which channel storm water into waterways), and building holding and treatment systems for storm water. As we noted earlier this week, Milwaukee is one city that's done this already: if there's too much water to be discharged safely, its deep-water tunnel holds onto the excess fluid until sanitation plants can clean it.

"Storm water pollution is harmful and complex and this comprehensive report offers new information and wide-ranging policy recommendations," Benjamin Grumbles, EPA's assistant administrator for water, said in a statement. "Sound science, pollution prevention, and watershed protection will ensure continued clean water progress."

(Updated at 2:20 p.m. with EPA comment.)

(Image by iStockphoto/Edward Shaw)