SEATTLE - Hundreds of people gathered on Saturday to help clean up the banks of the Duwamish River. It's an important Earth Day tradition that's made a big difference to one of Seattle's most polluted rivers over the years.

The volunteers got down and dirty pulling up weeds and planting new trees at nine different sites along the river.

"That's what it takes. It takes a lot of energy, a lot of enthusiasm and just grunt force work to pull all of these invasive weeds out and plant all of these new little trees that'll eventually grow up," said Kristin Holsman, a volunteer.

Volunteers say the massive clean up is the only way to restore the forgotten patches of nature.

"For more than 100 years, the Duwamish River has been our forgotten industrial backyard," said Kathy Fletcher with the group People For Puget Sound. "And of course, we're trying to get the natural vegetation to come back, because that's what's valuable to the wildlife."

The annual tradition was spearheaded by John Beal, a war veteran.

"A long time ago, he started coming out because he needed a place to be where it was peaceful, he was having a lot of health problems and was told he was going to die," said his wife, Lana. "And he said 'I'm just going to go by the stream and sit, and decided he was going to start picking things up."

Beal died last year, but his widow, Lana, says he would be proud of the volunteers' work.

"It's just been wonderful to see that they're continuing on what he had started," she said. "And there are a lot of environmental groups that have pitched in over the years."

Beal's work over the years inspired other veterans like Scott Swain to follow suit.

"One of the things that's common for veterans is they have so many common things with a lot of the people in the community they serve," he said. "We give back in a lot of different ways, and that's really all we want to do."