AUBURN, Mass. - Volunteers gathered for the 50th annual Zap the Blackstone cleanup on Saturday and left with trucks and trailers full of trash. 

Beginning early at dozens of sites, volunteers canvassed the riverbanks, turning up shopping carts, plastic bottles, car parts and anything else that didn’t belong there.

“I was expecting maybe one or two trash bags of nip bottles, and as you can see over here, it’s been probably an hour and we have about ten bags," said Adam Zwick. "We pulled out a bike as well.”

When 10,000 volunteers showed up for the inaugural Zap the Blackstone in 1972, it was the largest regional cleanup effort in U.S. history. 

Roy Kelley's grandfather organized the original event 50 years ago. 

“He was working on the river for years, and one of the things that he wanted to take care of was the pollution," Kelley said. "He got a lot of people involved, and that’s what we tried to do today. We got as many people as we could in a short timeframe, but we tapped into a lot of the volunteer organizations that already existed and brought them on board.”

All these years later, Mass Audubon ecologist Martha Gach said the cleanup and the volunteers' camaraderie remain as important as ever.

“We’ll clean it up, and a month later, it’ll have trash in it again," Gach said. "It just makes so much of a difference to the wildlife and to the people who come to visit. I think it’s always good for people to understand that they’re part of a bigger movement. The little bit they’re able to do, or the lot that they’re able to do, when you add it all together it creates this amazing collective achievement.”

If you missed Zap the Blackstone, volunteers like Katherine Zheng said you don't need to wait for next year's event to help out - there’s always a cleanup around the corner. 

“If you find a cleanup, go for it," Zheng said. "It’s fun. It’s good. You’re helping the environment. You’re with people. It’s a fun experience. You should do it!”