The ad shows a tiny Speedo swimsuit hanging from a clothesline.

The copy reads: “The scariest thing to hit the water since Uncle Jack showed up wearing one of these.”

Can a little humor persuade Rhode Islanders to change their ways and reduce the pollution flowing into Narragansett Bay? Several state agencies sincerely hope so.

They unveiled a new media campaign called “Know Where It Goes” yesterday designed to persuade people to minimize the pollution that flows into local waterways during rainstorms.

The so-called “storm water pollution” includes excess lawn fertilizers, pet wastes, and oil and other fluids that drip out of motor vehicles.

The state Department of Transportation is spending about $650,000 over four years on a comprehensive effort to reduce pollution from roads and other sources that flow into rivers and streams. About $50,000 of that budget is going for the ad campaign, which will use a Web site, buses, bus shelters and local radio stations to make people think and possibly to change their ways.

The project is a group effort involving the DOT, the state Department of Environmental Management and the University of Rhode Island’s College of Life Sciences. They also are preparing training manuals for municipalities, speaking programs for schools and seminars.

Leaders of the new campaign spelled out some of its ramifications to a group of campers from the West Bay YMCA at the Goddard State Park gazebo yesterday afternoon. The youths paid attention even though the beach and the Bay were just a few steps away.

Robert Weygand, vice president of administration at the University of Rhode Island and head of the university’s Council for Sustainability, told the students the school had already built the largest permeable parking lot in the state at URI’s Ryan Center. It provides parking for 2,000 cars, yet rainwater never washes off — it is designed to let water filter back into the ground.

Warwick Mayor Scott Avedisian said his city knows its 39 miles of coastline are its most valuable asset. That’s why the city is spending millions of dollars improving its sewers. He said he’s pleased the entire state will be working on one coordinated effort to further clean up the Bay.

DOT Director Michael Lewis sat down in front of the kids and explained how his roads are like trenches of sand people dig at the beach. Whenever something spills, Lewis said, roads and sand trenches take it right to the nearest body of water.

Lewis added that DOT litter crews picked up 73,000 bags of litter from along Rhode Island roads last year. It’s time, he said, for people to accept more personal responsibility.

DEM Director W. Michael Sullivan said that during last year’s coastal cleanup, 14.5 pounds of cigarette butts were collected. He asked the kids to try to imagine how many discarded butts it must have taken to weigh that much.

Save the Bay’s John Torgan warned that on Tuesday he did some sampling that showed very low oxygen levels in the Providence River, a condition that can lead to fish kills or beach closures.

“We’ve seen dramatic improvements in water quality in Narragansett Bay,” Torgan said. “But storm water pollution is still a serious environmental problem.”

For more information on the campaign, go to: www.ristormwatersolutions.org.

plord@projo.com