Is it safe to swim in the Chesapeake Bay and its tributaries? Depends on who you are, and whom you ask.

Under the 2000 Beach Act, the EPA required states to establish water quality criteria for beaches. States and counties are supposed to test the beaches regularly and post warnings when the beaches exceed their allowable levels for bacteria. In Maryland, health officials advise swimmers to stay out of the water within 72 hours of a rainstorm.

But in practice, swimmers dive into the water as soon as the rain stops, and few are counting the hours. And many swimming holes, creeks and runs do not meet the definition of beach, so they’re not monitored, even though people swim there.

The Chesapeake Bay Foundation decided to help fill the gap this summer. It partnered with three small colleges — Hood College in Frederick, Howard Community College in Columbia, and Harford Community College near Bel Air. The colleges sample water in popular recreation areas and test the samples in their labs. The testers looked for enterococci, a fecal bacteria that can cause diarrhea and other intestinal problems when swallowed.

The testing partnership found bacteria counts were 50 times higher than what the EPA considers safe at Kilgore Falls, a waterfall in Rocks State Park in Harford County that is a popular swimming hole in the summer. In Walkersville, a Frederick County town, impervious surfaces and development have helped to push levels in the Glade Run stream to 200 times the safety limits after a half-inch of rain. Columbia’s lakes fared better, but were still three times higher than the EPA levels after a rainstorm.

“It’s a real back-burner issue for folks. They’re making some relative risk calculations. It’s lack of information, a lack of people talking about this issue,” said Doug Myers, a foundation scientist working on Maryland issues. “It’s a complicated issue for folks to talk about. We’re raising that issue a little bit with these samples.”

This is the second year of the testing program, which the foundation is funding through its own resources. The first year, it worked with Anne Arundel Community College, which already had an established testing program. Staff will decide next year whether, and where, it will continue the program.

The CBF program is not the only one testing water to determine bacteria levels. Along the Severn and Magothy rivers, several community associations pay Sally Hornor of Anne Arundel Community College to test their water twice weekly. That information is posted on her website, Operation Clearwater. Residents, including the counselors who run Sherwood Forest Camp, use it to make daily decisions on whether to swim.

Riverkeepers test their water and upload data to their Swim Guide, an app that provides information on Chesapeake rivers. Many of these riverkeepers, including Jeff Holland on the West and Rhode rivers, also keep e-mail lists and send out alerts when counts become too high at popular beaches.

But many waters remain untested, and many kayakers, swimmers and paddle boarders are unaware of the risks.

While the flesh-eating bacteria vibrio commands the most attention because it can be fatal, more common strains of bacteria cause more minor health problems such as intestinal discomfort, cellulitis and diarrhea. Swimmers often don’t seek medical attention for minor problems; and when the infection becomes more serious, as in the case of cellulitis, the doctors don’t always report the problems to the health department.

Myers said the Bay Foundation undertook this testing in part to show residents the consequences of too much nitrogen and phosphorus entering our waterways, and the remedies for it — such as better stormwater systems — are worth the expense. People connect to infections from water and notices posted saying they can’t swim because of pollution more than they do to talk of impervious surfaces and runoff, Myers said.

If the testing gives the health departments extra incentive to do their own beach checks more often, and before or after rains to get comparisons, Myers said the effort will have been effective.

“With a little bit of extra effort at local level, people can be more informed,” he said.