More than 12,000 volunteers hauled tires, plastic bags and even a Canadian flag-with the pole still attached-out of the Potomac River this spring.

The effort was part of the Trash Free Potomac Watershed Initiative, which aims to have the Chesapeake Bay's second largest tributary free of litter by 2013.

Judging by what volunteers found during this cleanup, they have a long way to go. Volunteers picked up 1,844 tires, 21,000 plastic bags and a whopping 190,000 beverage containers, many from 7-Eleven and McDonald's.

Every year, though, there are surprises. This year's included a gumball machine with the gumballs still inside, a Vespa motor scooter, barbed wire and cancelled checks-from 1985. "It was all kinds of strange stuff this year," said cleanup coordinator Becky Horner,

In all, the 575 cleanup sites along the river collected 222 tons of trash. The sites ranged from rural West Virginia to urban D.C. to increasingly suburban St. Mary's County in Southern Maryland. The cleanup spans a month, with sites getting anywhere from two volunteers to more than 400, Horner said. Occasionally, an entire school participates.

The cleanup has been going on since 1989 and is sponsored by the Alice Ferguson Foundation, which focuses on environmental education in the Potomac River watershed. It now has the support of the region's environmental leaders as well as two powerful congressmen, Majority Leader Steny Hoyer and Chris Van Hollen, both Democrats. More than 140 leaders have signed the foundation's Trash Treaty, acknowledging the problems that garbage contributes to the watershed and pledging to clean it up.

Although it doesn't get as much attention as nitrogen and phosphorus in terms of the Bay's overall health, trash is a major polluter. "It's a public health issue," Horner said. "It's in drinking water. It's a major problem, all in itself."

Horner said that the amount of trash collected grows every year, but that is because the foundation keeps adding new sites. Between last year and this one, she said, the trash per volunteer collected decreased-a flicker of hope for the 2013 goal.

To see a video and photos of the event, visit www.fergusonfoundation.org/trash_initiative/trash_index.shtml.