Leave your feedback Share Copy URL https://www.pbs.org/newshour/show/polluted-rain-run-off-poses-threat-to-water-systems Email Facebook Twitter LinkedIn Pinterest Tumblr Share on Facebook Share on Twitter Transcript In a landmark decision, a Washington state pollution board has ruled that flow of polluted storm water into local water systems must be reduced. Lee Hochberg reports on the ruling and controversy over the impact of new home developments on the problem. Read the Full Transcript Notice: Transcripts are machine and human generated and lightly edited for accuracy. They may contain errors. LEE HOCHBERG, NewsHour Correspondent: When it rains — which is pretty common in the Northwest — most people look at the sky. Water pollution experts look at the ground.And what they see disturbs them: chemicals, and motor oil, and herbicides washing from neighborhood streets and yards into creeks and bays.Half of U.S. water pollution comes from storm water run-off. In Seattle, it's responsible for more than 70 percent of the zinc and copper that winds up in Puget Sound, heavy metals that are toxic and kill Sockeye, King and Coho salmon, protected under the Endangered Species Act. CURT CRAWFORD, Storm Water Manager, King County, Washington: Well, this is the typical type of development that we're seeing now. And there are better ways of doing it. LEE HOCHBERG: King County's storm water manager Curt Crawford took us to a typical subdivision outside Seattle. Though it's only 24 acres, as many as 200,000 gallons of polluted water drain off of it after a normal rainfall. CURT CRAWFORD: When you clear those trees away and you put in these roads, impervious surface, you put in new roofs, it can be as much as a 300 percent increase in run-off volume.