Trash volunteers collected thousands pieces of debris from balloons during cleanups along the shores of the Great Lakes in the past few years, The Detroit Free Press reports.

The newspaper reports that data from the environmental group Alliance for the Great Lakes shows that trash volunteers have cleaned up more than 18,000 pieces of waste from balloons from the lakes’ shorelines spanning from 2016 to 2018. The cleanup efforts were reportedly carried out by the nonprofit’s “Adopt-a-Beach” program, which gathers volunteers each year to cleanup trash along the shorelines.

Jennifer Caddick, a spokeswoman for the nonprofit, told the paper that the group’s volunteers collected anywhere between 4,400 and 7,200 items of balloon waste annually as part of its program during the three-year period.

“It’s really dramatic and troubling,” Caddick told The Detroit Free Press. “It paints a picture of the bigger plastic pollution problem plaguing the Great Lakes, our oceans, and really the entire planet.”

Caddick’s comments come as a number of states across the nation have passed legislation banning residents from intentionally releasing balloons. According to the paper, New York, New Jersey and Massachusetts are a few states that are considering enacting similar measures.

“It’s a huge problem — washed-up balloons on the beach are huge,” Pamela Denmon, a biologist with the U.S. Fish and Wildlife Service, told the paper.

“Every day we could go out and pick up balloons. We actually have people that write on balloons their phone number because they want somebody to call when they find it.”

Christina Trapani, who works as a volunteer at the Eastern Shore of Virginia National Wildlife Refuge in Virginia, told the paper that “people don’t think about” the release of balloons as “being litter.” Trapani said.

“There might be balloon bans in some places and not in others,” she continued. “But it doesn’t matter when you release it — they can end up in these places.”

“The bottom line is, when you let go of a balloon, you’re littering,” the cleanup volunteer added. “You wouldn’t dump a bunch of uninflated balloons on the ground.”