But between the scary looking "floaties" and an unrelated drop in fish numbers, some people who use the river for recreation are worried.
"There's just a bunch of things coming together. You hear people talking about it. You wonder what's up," said Ron Ambrose, 45, who lives near Shepherdstown, W.Va., and uses the river for boating and fishing.
Government officials who monitor river conditions said there is reason for concern about the river, especially with the expansion of poultry farms and cattle feed lots in the Potomac Headwaters of West Virginia.
But they say the river is not in critical danger, as some environmental groups have charged.
In April, the national conservation group American Rivers named the Potomac to its list of the 10 most endangered rivers in North America.
In the wake of that announcement, the West Virginia Rivers Association predicted that communities along the Potomac could face their own version of Milwaukee's deadly 1993 cryptosporidium outbreak.
"It's disheartening that people in the Potomac Valley need to worry about getting sick from the drinking water coming from their tap. Or that parents might have to keep their children from playing in the river," association director Roger Harrison said in a recent newsletter.
But Michael Arcuri, environmental resources specialist supervisor at the West Virginia Department of Environmental Protection, disagrees that there are serious problems with the river.
"I don't think it's time to push the panic button at this point," Arcuri said.
That doesn't mean there isn't cause for concern. The river is suffering from "moderate" pollution, he said.
In drought conditions like the area has seen this summer, any chemicals in the river become more concentrated, he said.
State and federal governments are monitoring the effects of agriculture, timbering and construction, activities found in nearly every watershed, he said.
So far, the industries have not had any detrimental effect on the Potomac River, said Patty Manown, spokeswoman for the Maryland Department of Natural Resources.
Fishermen may perceive problems with the river because of a drop in smallmouth bass numbers this year, she said.
However, the fish kill is being blamed not on pollution but on weather conditions. Last year's flooding stressed the fish population and water temperatures this spring remained cold longer than normal, said Ed Enamait, natural resources fisheries manager.
The Potomac is nowhere close to being as polluted as it was before a massive clean-up effort in the 1970s.
"I don't think it'll ever get that bad again. I pray that it doesn't," said John Norris of Pathfinders in Hancock, which rents canoes and bicycles.
Norris, 41, grew up in Hancock and remembers the Potomac when it was black and greasy.
"To look down into the water 25 years ago, you couldn't see the bottom and it just looked black," he said.