In 25 years of cleaning up the Potomac River, volunteers in the Annual Potomac River Watershed Cleanup have seen it all: refrigerators, cars, beer bottles — even toilets cast off into the nation's river.

This year's cleanup was no exception. As of late April, 5,723 volunteers collected 286,500 pounds of trash from more than 200 sites in the District of Columbia, Fairfax, Loudoun, Charles, Prince George's, Prince William and Montgomery counties.

Among the trash collected: 10,700 cigarette butts, 433 tires, a rolled-up carpet, a 50-foot long PVC pipe and a toilet bowl, according to Alena Rosen, who coordinates the cleanup for the Alice Ferguson Foundation. Other somewhat puzzling finds included a headless goose decoy, an air mattress, some trash cans and one ski.

One item they didn't see a lot through some parts of the watershed: the once-ubiquitous plastic bag. For a long time, the blue and white plastic grocery and superstore bags were a staple of the cleanup, along with beer and soda bottles. But the District of Columbia put in a 5-cent fee on plastic bags in 2010, and Montgomery County followed their lead with its own "bag bill" that went into effect last year.

It made a big difference, Rosen said. Site leaders in the District reported far fewer plastic bags. Meanwhile, on the other side of the river, it was business as usual. One site in Fairfax County reported 2,000 plastic bags; another, in Loudoun, reported 800.

"It's definitely making a difference," said Julie Lawson, communications and campaigns manager for the Anacostia Watershed Society. Lawson was also volunteering at the river cleanup; at her site in Montgomery County, she said, she only saw four plastic bags.

The Anacostia Watershed Society estimates that plastic bag litter has been reduced by 50 percent in DC and 60 percent in Montgomery County since the bag bills went into effect.

With the jurisdictions in the nation's capital so close together, it's easy to see a difference between the bag-bill cities and the ones where the law is not in place.

"It's very noticeable when you're driving and you get off at the Prince George's side of the Anacostia," Lawson said." There's a lot more bags floating around."

Lawson worked with other environmental activists and DC City Council members to pass a statewide bag bill in Maryland's General Assembly this session, but it was defeated. She said they will try again next year.

The Potomac River cleanup continues throughout April and May. For information about it and the Trash Free Potomac Initiative, visit http://fergusonfoundation.org/trash-free-potomac-watershed-initiative.