As a kayaker, Bruce Cohn has a tentative relationship with the homeless who camp along the banks of the Petaluma River.

"Oh, yeah, they all know me," the Petaluma resident joked recently while walking along the river's northern reach near the Petaluma Village Premium Outlets, pointing out trashy areas.

Cohn has been trying — without luck so far — to bring attention to the litter and environmental damage created by the homeless along the far stretches of the river, places most people don't venture into.

During his frequent paddling trips up the river, Cohn collects as much trash as he can. But much of it he can't reach from his perch in his kayak. He said he pulls out 25 pounds of trash three or four times a week.

For all of his love for the river, he said it disgusts him to see the degradation of the serene beauty and natural habitat that is protected from most people by its very geography.

"It's just nasty. I fished a fire extinguisher out the other day," he said. "There are three sleeping bags in trees. There's a baby carriage, a newsstand, a car door."

Cohn said he is worried some of the debris will flow out with the tide, further contaminating the slough that winds toward San Pablo Bay.

His calls to law enforcement got bounced around to different jurisdictions. His efforts to alert river groups in Petaluma were rebuffed, he said, his photos of the trash removed from their web pages.

"I understand they need a place to live," Cohn said. "But if it's free, at least clean it up."

Most of the cans, plastic bags, empty food containers, sleeping bags and other flotsam the homeless leave on the banks and in the river gets swept toward the bay, gets snagged on vegetation or rots away on the banks.

The camps can be an environmental nightmare, said Petaluma Police Lt. Tim Lyons. Often the homeless bathe in the river or use it as a toilet. Their trash can contain any number of contaminants or harmful fluids.

"We had a rash of vehicle battery thefts and we found they were using the batteries to power everything," Lyons said, including satellite TV in one camp.

Cohn said those living near the river cut steps into the banks so they can climb down to water's edge.

That creates erosion along the banks, especially during the winter when heavy rains fill the river and streams, which flow into the river and eventually into San Pablo Bay via the tidal flow.

The Sonoma County Sheriff's Office and state Department of Fish and Wildlife occasionally respond if there are complaints about trash or environmental damage.

But Lt. Steve Brown said there haven't been any concerted efforts to remove the homeless around Petaluma recently.

When there are complaints, Lyons said, police will visit the camps and alert the residents they need to leave within 72 hours. Any property left behind is thrown out.

Cohn has seen some pretty elaborate campsites, including one with a shower created with burlap sacks. He once found a discarded barbecue grill.

David Keller, who is on the Petaluma River Council, said the areas Cohn sees are inaccessible and difficult to cart trash out of.

"You risk being harassed and threatened by people who live in the camps," he said, explaining why some cleanup efforts don't include those areas.

"It's an area of the Petaluma River that ironically is the most beautiful riparian habitat. It's so valuable," he said. "It does need to be cleaned up and it does need to be patrolled on a regular basis to keep the camps from being re-established."

Last year, four 40-cubic-yard debris boxes were filled during the community river cleanup. This year's cleanup is May 5.

(You can reach Staff Writer Lori A. Carter at 762-7297 or lori.carter@pressdemocrat.com.)