Some of them are after nothing more than a leisurely float down the river. Tubing has long been a hot-weather institution for Maryland families, who used to walk up the old railroad bed, throw their inflated rubber rings in the water and drift back to Monkton Station.
"It's the Preakness of tubing destinations," says Theaux Le Gardeur, the Gunpowder Riverkeeper, part of a network of volunteers who act as stewards of the state's waterway.
In this case, the revelry sparked by enterprising business owners could cause officials to curtail the tradition.
Two weeks ago, state park rangers pulled the parking permit for one tubing vendor for violating the alcohol clause in his agreement. Days later, a state fisheries commission voted unanimously to ask the Department of Natural Resources and the Maryland Park Service to restrict activities in a 7.2-mile section of the Gunpowder nationally known for its trout fishing.
"We need to put the park service on notice," says James Gracie, chairman of the Sport Fish Advisory Commission. "It's unfishable on weekends."
But one of the tubing vendors says the Gunpowder is for everyone and he doesn't have the authority to inspect coolers and backpacks before customers shove off down the river.
Besides, says Gary Kloch, it's unfair to blame his business alone.
"Some people have their own tubes and they bring their own alcohol and they leave behind their own trash," he says. "A lot of my customers are families that behave themselves and are just here to have fun."
Like Mike and Barbara Axelsson of Monkton, who were entertaining their four grandchildren on a recent 100-degree day.
"It was something we did with our children years ago and now we're sharing it with them," said Barbara as she helped load Bailee, Emilee, Carter and Riley, all under the age of 10, into tubes and give them a push. "We're trying to give them an appreciation of nature."
Betsey Gilbert of Baltimore wants to take her son, Matthew, 7, tubing as soon as he is a little older to continue a tradition she began as a child.
"I like that it's so close to Baltimore and my son and I have been talking about it for two years," she said.
"But I don't want to bring my son to a frat party."
A flash point
It's not the first time that the Gunpowder has become the flash point for conflicting recreational uses.
Four years ago, the Greater Baltimore Canoe Club and members of Maryland Trout Unlimited had a showdown over downed trees in the river. What the paddlers saw as a safety hazard, the anglers viewed as the perfect natural habitat for trout. The matter had to be resolved with state intervention and a written policy.
But the Gunpowder tubing season is much shorter and problems take on a sense of urgency, says Todd Huff, the Baltimore County council member who represents the area.