Why does no one swim in the Potomac? Would my skin fall off if I jumped in? Would I contract some horrible disease? Would I be devoured by angry snakeheads? -- Emily Moody, Gaithersburg

To answer those questions in order:

Some people do.

Probably not.

You might.

No.

The Potomac is a big river -- 400 miles from where it starts in Western Maryland to where it empties into the Chesapeake Bay -- so we can't talk about it as if it was just that segment we see cascading over Great Falls, then sweeping past the Wilson Bridge.

But we'll concentrate on the river in our back yard first. One reason people don't -- or shouldn't -- swim around here is because it's illegal. District law stipulates that it is unlawful to swim in the part of the Potomac that passes through Washington. Swimming also is prohibited from the banks of public parks in Maryland such as Fort Washington and Fort Foote.

The main reason is safety. It's obvious at Great Falls that the Potomac is treacherous; the angry, roiling waters have "liquid death machine" written all over them. Even relatively placid stretches of the river downstream can hide dangerous shifting currents.

Those are what you might call the mechanical reasons you shouldn't swim in the Potomac.

Then there are what might be called the bacteriological reasons. At various points along the river, including in Washington, storm runoff and the contents of toilets both flow into the same place: the sewer system. This is a problem when there are storms. Heavy rains can overwhelm treatment plants, allowing raw sewage to backflow into the Potomac.

You wouldn't want to be swimming in that, uh, stuff. That stuff, specifically, is fecal coliform bacteria, three words that I don't even like saying.

Your skin probably wouldn't fall off if you came in contact with fecal coliform bacteria, but you might contract some disease. Ed Merrifield of the citizens group Potomac Riverkeeper said that his kayaking friends have told him of getting ear infections after rolling in the Potomac. Rowers splattered in the face with river water have been known to develop eye infections.

People who monitor the Potomac say it's cleaner than it once was -- back in the 1970s, it was pretty bad news -- but not as good as it could be. It's certainly not the pristine waterway that Native Americans gamboled in centuries ago. They weren't the only ones who enjoyed its waters. Both President Adamses, John and John Quincy, liked to take the three-block walk from the White House to the Potomac for a bracing morning paddle. In fact, John Quincy Adams is said to have been a frequent skinny-dipper, swimming in the Potomac in the buff well into his 70s.

Where would a president eager to sink his naked form into the Potomac go these days? Maybe to Bill Sonnik's place. Bill is president of the Potomac Fish and Game Club, a private, 550-acre retreat on the river near Williamsport, Md. Every summer, they dump a bunch of sand near a launch ramp to create a makeshift beach.

"The swimming's great," said Bill. "It's a rare weekend there aren't kids paddling around at the foot of our boat ramp. I've never heard of anybody getting ill, or any cautions. Obviously, when the river's high or swift, common sense would say you don't get in. But every Sunday afternoon, we take the float boats out, find some shallow water, throw the lawn chairs in the water and have a good old time."

Bill says the river's pretty narrow there. You can knock a ball over it with a golf club (well, he can; I'm sure Answer Man can't). Things are different where the Potomac ceases to be. It's 11 miles wide at Point Lookout, at the Chesapeake. They have swimming beaches there, and some even have lifeguards. You can wade into the Potomac from the Virginia side, too, in Colonial Beach.

As for the latest threat -- death by snakehead -- Bob Lunsford, biologist at the Maryland Department of Natural Resources, said: "Absolutely not. And you can quote me on that. They have no interest in bothering something bigger than themselves. If you look like a smaller fish, you might be in trouble."

Bob said a snakehead is no more a danger than the pickerel, another fish with teeth that swims in the Potomac. "No one's ever been attacked by a pickerel," he said.

Note: If you have been attacked by a pickerel, please let Answer Man know. He's shopping around for screenplay ideas.

Send a Kid to Camp

I'll be heading out to Camp Moss Hollow on Wednesday to see firsthand the kids who are benefiting from Post readers' generosity. Thirteen of the $260,000 or so dollars we've raised came from Griffin Baltz, 10, of Laurel. "I've been keeping money for charity and would like to donate some to Send a Kid to Camp," Griffin wrote.

That's the spirit. I figure if every single reader of this column gave $13, we'd reach our $750,000 goal by July 23.

Here's how you can contribute: Make a check or money order payable to "Send a Kid to Camp" and mail it to: Attention, Lockbox, Department 0500, Washington, D.C. 20073-0500. To contribute online, go to www.washingtonpost.com/camp. Click on the icon that says, "Make Your Tax-Deductible Donation."

To contribute by phone with Visa or MasterCard, call Post-Haste at 301-313-2200 on a touch-tone phone. Then punch in KIDS, or 5437.

Researcher Alex MacCallum contributed to this report.