Fecal matter, it's enough to make you wonder whether you'll ever want to jump in the water again. But it's summer after all, and what's summer without a dip in the bay or a spin on the water skis.
Now there's a way to know how much fecal bacteria is in your chosen body of water.
The Maryland Department of the Environment posts swimming advisories on an interactive online map at marylandhealthybeaches.com. Beaches closed because of high bacteria readings are shown with red markers; safe beaches are shown in blue.
A smartphone app is in the works for the MDE beach data.
All Maryland counties with shorelines test water. Anne Arundel County has the most robust government testing program, with about 90 test sites along the county's more than 500 miles of shoreline.
Anne Arundel's Health Department tests waterfront locations on a weekly, biweekly or monthly basis to measure enterococci, bacteria that indicate waste from a warm-blooded animal in the water.
Closed beaches are marked with yellow warning signs and noted on email and Twitter alerts, as well as listed on a recorded phone line. Advisories are posted online at aahealth.org/beach.
Neighborhood associations and environmental groups pay Anne Arundel Community College to test about 40 more sites on the Magothy, Severn, South, West and Rhode rivers.
Tests begin before Memorial Day and continue through Labor Day. Results for both programs are posted online.
Baltimore County, with nearly 200 miles of shoreline, tests about two dozen locations two to three times per month and posts the results online at baltimorecountymd.gov/Agencies/health/environmentalhealth/watersampling/index.html.
"People can use that information to adjust their use," said Sally Hornor, a biology professor who has run Anne Arundel Community College's Operation Clearwater for 28 years. "It doesn't mean they can't use the water, just that they need to be careful."
Bacteria can get into waterways in a number of ways, including sewage spills, leaky septic systems, untreated waste from boat toilets, animals (such as geese or dogs) and from stormwater runoff.
Swimming in bacteria-laden water can cause gastrointestinal illnesses. Health officials say people should not swim in natural bodies of water if they have compromised immune systems, ear infections, a perforated eardrum, open cuts or skin lesions. Everyone who swims in natural bodies of water should wash well afterward.
In Arundel, the county and college programs test water samples and count colonies of bacteria. For county-tested sites, officials will close beaches to swimming if counts are too high, based on Environmental Protection Agency standards. Usually, the limit is 104 or 158 colonies of bacteria per 100 milliliters of water, depending on frequency of testing and how many people swim at the site.
The county warns against swimming in creeks, rivers or the Chesapeake Bay for at least 48 hours after any rain of a half inch or more. That's because stormwater washes bacteria and other pollutants into the water. The county also does not do bacteria testing within 48 hours of a rainfall, because bacteria counts predictably rise.
The county does not officially close beaches that are tested through the college's Operation Clearwater program. The college works with its participating groups, including Riverkeepers, to spread the word of high bacteria levels. Some communities post the data on Facebook or bulletin boards at beaches.
For Operation Clearwater test results for the Magothy and Severn, go to ola2.aacc.edu/tldomanski. For the South River, visit southriverfederation.net under "river health," and for the West and Rhode rivers, go to westrhoderiverkeeper.org under "programs."
The nonprofit Riverkeepers have their own nationwide website and app that shares their independent test results and government results called the Waterkeeper Swim Guide.