Rulings Restrict Clean Water Act, Foiling E.P.A.

The Clean Water Act was intended to end dangerous water pollution by regulating every major polluter. But today, regulators may be unable to prosecute as many as half of the nation’s largest known polluters because officials lack jurisdiction or because proving jurisdiction would be overwhelmingly difficult or time consuming, according to midlevel officials.

“We are, in essence, shutting down our Clean Water programs in some states,” said Douglas F. Mundrick, an E.P.A. lawyer in Atlanta. “This is a huge step backward. When companies figure out the cops can’t operate, they start remembering how much cheaper it is to just dump stuff in a nearby creek.”