Last weekend, stenciled white fish began appearing next to drains around the River Houses, part of a local high school student's effort to combat pollution in the Charles River.

Ben Bruckner, a senior at Cambridge Rindge and Latin School, gathered about 30 volunteers to paint the awareness messages, reading "Please Don't Dump. Protect the Charles River," next to 'catch basins,' or street drains, throughout Cambridge.

A member of the Cambridge Council of Boy Scouts, Bruckner organized the project to fulfill one of his requirements to become an Eagle Scout, and also to educate the community.

"Most people think the catch basins lead to sewers so they dump trash in them. But they really lead to storm drains that overflow into the Charles River," Bruckner said.

Though Bruckner says he didn't know it when he conceived of the project, the stenciling coincides with a citywide clean-up effort.

The Department of Environmental Protection has ordered Cambridge to try to make the city cleaner by 2005, according to John Nardone, a senior collections engineer at the Department of Public Works (DPW).

Keeping trash out of the catch basins will help the city meet that goal.

Bruckner's stenciling, though it had to be approved by the DPW, was independent from the city--Bruckner initiated the project and did not use city materials.

His stenciling project is one of many nationwide, said Gillian Grossman, the program coordinator for Save the Harbor, Save the Bay, a Boston conservationist group.

Stenciling has become an effective way to let residents know their actions have consequences, she said.

"It helps people realize that what goes down these drains ends up in our waterways, like the Charles River, and eventually in Boston Harbor," Grossman said.

Other Boston-area groups, like the Charles River Watershed Association, have also been stenciling catch basins throughout the year.

The popularity of this movement can be attributed to a shift in focus on the part of local activists.

In past years, environmental groups targeted companies dumping pollutants in both the Charles River and the Boston Harbor.

Now, with the river and harbor much cleaner, storm drain pollution is the main source of pollution in the Charles River, she said. As a result, activists are trying to get residents involved in the movement.

"People don't realize that the drains may empty into the Charles River," said Kris Finn of the Charles River Watershed Association. "Even if people live a mile away, their storm drains may still empty in the river."