The EPA, opening a new line of attack on water pollution, imposed sweeping new requirements on cities and industry to develop programs for reducing contaminated runoff from streets, landfills, factories and construction sites.

In the first government effort to address "poison runoff," the Environmental Protection Agency issued regulations Monday under which some 100,000 industrial plants, 173 cities and 47 heavily populated counties will have to take steps to minimize pollutants that might be picked up by rainwater.Under the program, cities and industry will have to obtain discharge permits from the EPA or state government for storm water sewers that collect runoff water from street drains and ultimately dump it into rivers and lakes.

In flowing down city streets and industrial sites into drains, runoff picks up grease, toxic metals, pesticide residues and larger debris that is not subject to any decontamination treatment before final discharge.

EPA and state officials say such "non-point" pollution - as opposed to wastewater discharges from specific effluent pipes - is the largest single cause of water contamination.

Environmentalists said the EPA's new regulatory program was a long overdue effort to address a little-noticed but massive contributor to water pollution.

"Poison runoff has been neglected for far too long," said Richard Cohn-Lee, a research expert on water contamination for the Natural Resources Defense Council.