It is Earth Day weekend 2018, and around the Garden State thousands of volunteers will wade into streams and rivers to pull hundreds of tires and tons of bottles, bikes and all other types of trash out of rivers and waterways.

Since the first Earth Day on April 22, 1970, new laws fighting the most toxic and dangerous pollution of land, water and air have continued to improve the environment. But while environmental health in New Jersey has improved drastically since 1970, problems persist.

The most visible problem? Litter.

To this day, trash continues to make its way from roadsides to riverbeds in massive quantities.

The culprit? Humans.

The good news is that efforts have sprung up all around the Garden State to fight the trashing of our waterways.

Along the 21-mile long Passaic River, the Passaic Valley Sewer Commission has used a trash skimming boat to pull garbage directly out of the water since 1999. Since the program began, the skimmer has pulled about 3,050 tons of plastic bottles, styrofoam containers, aluminum cans and other garbage out of the Passaic.

In 2005, the PVSC began supplementing the skimmer operations with community cleanups of the river banks. PVSC spokesman Doug Scancarella. Scancarella said more than 270,000 volunteers to date have helped clean more than 9,000 tons of trash off the banks of the Passaic.

The constant stream of litter flowing into the Passaic, combined with the trash brought in with the tides, is frustrating to the people who work to clean the river. But Scancarella said that doesn't diminish the work being done.

"It's hard to quantify what [the river] would look like if we weren't doing it," Scancarella said.

In Central Jersey, Bill Schultz, the Raritan Riverkeeper, says work to clean trash out of the Raritan has surged in recent years.

"We're seeing a resurgence in interest in the Raritan River," Schultz said.

Schultz said that dam removal and toxic site remediation has helped the Raritan regain its health, but garbage in the water and on the river banks remains a persistent problem.

"Litter is a human behavior. That's one of the concerns that I still have," Schultz said. "I'm not sure that we're making the progress that we need to."

Schultz points to the Central Jersey Stream Team, a small nonprofit, as a model of volunteer river cleanups.

"This is the gang that is in the mud," Schultz said. "They are digging tires out of the riverbed. It's fantastic."

Jens Riedel, the president of the nonprofit, said they've pulled more than 4,000 tires and tons of trash out of the Raritan River and its tributaries to date.

The group has cleaned the entire main stem and south branch of the Raritan from Clinton to Piscataway at least once since the cleanups started.

Riedel says most of the trash they find is plastic bottles and food containers, but bicycles and mattresses have been pulled up before. They've even helped dig three cars out of the river in Bridgewater, near Duke Island Park

Clean Ocean Action's spring beach sweeps, April 22, 2017 28 Gallery: Clean Ocean Action's spring beach sweeps, April 22, 2017

Along the Shore since 1985, Clean Ocean Action organizes two major "beach sweeps" each year in April and October. The events typically take place at more than 60 locations simultaneously, drawing thousands of volunteers.

"It's really exciting to me to see the thousands of people that turn out," said Cindy Zipf, the executive director of Clean Ocean Action. "I think it shows the Jersey pride that we have for the Jersey Shore, but more importantly that people are recognizing the impact."

The state gets in on the cleanup action too. Since 2011, the state Department of Environmental Protection has organized "blitzes" of Barnegat Bay aimed at cleaning up litter throughout the important South Jersey watershed. Larry Hajna, a spokesman for NJDEP, said that about 27,000 volunteers have picked up about 4,200 cubic yards of trash since the program started.

The clean up work across the state is important, but it only mitigates the larger pollution problem.

"Clean ups are great, but we are advocating to stop plastic pollution at the source," said Sandra Meola, the policy and communications director for NY/NJ Baykeeper.

For her group, Meola said, that means pushing for a statewide fee on plastic and paper bags, a statewide ban on styrofoam food containers in public schools and universities and a statewide ban on the intentional release of balloons.

There's a common theme shared by waterway advocates across the Garden State: Cleaning up trash is important, but the positive effects are diminished by people continuing to dump garbage and litter across New Jersey.

"As a society, we have to learn that our rivers are not acceptable garbage cans," Schultz said.

Michael Sol Warren may be reached at mwarren@njadvancemedia.com. Follow him on Twitter @MSolDub. Find NJ.com on Facebook.