It's the time of year when residents of Anne Arundel County's waterfront communities begin to think about heading to their neighborhood beaches for a dip - and the urge to hit the water means another warm-weather ritual is under way.
For the 28th year, the Severn River Association has begun Operation Clearwater, a program to provide areas on the Severn River with regular testing of the water quality in their swimming and water recreation spots.
During the 16-week program, which continues through Labor Day, test results are posted on the association's Web site, www.severnriver.org, and community representatives are notified of high bacteria counts, if any appear.
" `Is the water fit to swim in?' is the question we want to ask," said Sally Hornor, a professor of microbiology at Anne Arundel Community College, who runs Operation Clearwater out of the college's environmental center. "Generally, what the community wants sampled is the area where little children would swim, in the shallow water off the beach."
The Health Department conducts countywide water-quality testing at nearly 80 sites throughout the summer, but Operation Clearwater provides more detailed data to communities on the Severn River.
Testing for Operation Clearwater began May 15 at about 15 sites. Within the next few weeks that number probably will increase to 25, as more community associations sign up for the service, Hornor said. The program offers 16 weeks of testing for $320, or eight weeks for $160.
Each Wednesday morning, one of Hornor's students - working for Operation Clearwater for the summer - collects water samples and brings them to the college lab for analysis. Hornor posts the data online the next day.
For the second year, Operation Clearwater is testing for the bacteria group enterococci, instead of fecal coliform bacteria. Both organisms are found in the intestines of warm-blooded animals, but recent studies have shown that the presence of enterococci bacteria is a more accurate indicator of water quality.
The Environmental Protection Agency recommends against swimming when enterococci counts exceed the accepted levels of 35 per 100 milliliters of water.
If the counts are above the recommended levels, Hornor notifies a contact for the area.
"Communities have various responses," she said. "Some regularly post data to let people know, some don't do anything.
"This is a way to let community members know what the status of the water quality is, and they can make their own decisions," Hornor said.
Bacteria counts from creek to creek, and within the same creek, can vary widely, and they may be affected by rain and the amount of birds in the area. Also, the bacterial organisms usually don't live for more than 24 hours.
Last summer in Epping Forest, for example, a count of 430 taken after a rain was followed the next week by a count of 20.
"If we get a heavy rain, then the counts just go sky-high," Hornor said. "A lot of material gets washed into storm drains."
In her years of collecting data for Operation Clearwater, Hornor has recorded consistently high counts at Herald Harbor, a finding she has attributed to the large number of birds in the area.
"But these past two weeks we've seen very few birds, and the counts are really low," she said. "It's interesting, I don't know why the birds aren't there."
During the summer, the county Health Department samples water for enterococci from 78 creeks and streams throughout the county. The department is training college students to begin the sampling program, said Gerard A. Zitnik, program manager for housing and food protection with the department.
The Health Department samples are taken weekly, and posted on the department's Web site at www.aahealth.org. They are also reported on a 24-hour information line: 410-222-7999.
"There are sites in Anne Arundel County where historically we've had some high results, and these sites are well-known and well-documented," Zitnik said.
Areas that have been closed to recreational activity by the county in recent years include the headwaters of Rock Creek, and sections of Furnace and Marley creeks.
Zitnik said the department doesn't close a beach or creek based on one high bacterial count, but reviews an accumulation of data to make a decision.
"We're not going to make that determination on the merits of one sample coming back high," he said.
According to its Web site, the Health Department issues safety advisories and creek closures for recreational use only when a sewage spill or leak indicates that human waste has been discharged into the water.
But Hornor said most of the communities that participate in Operation Clearwater, rely on the weekly bacteria counts to make an informed decision about using their neighborhood beaches and creeks.
"There's no direct evidence that people can become ill from swimming in waters contaminated with bacteria that come from birds, but would you want to swim in it?" Hornor asked. "I think it's important to know about it, no matter what the sources."