At Delaware's beaches, scientists test waters for signs of fecal bacteria

LEWES, Del. (AP) — Most people probably don't think much about all the organisms riding the tides of Delaware's coastal waters. Sharks might come to mind. Whales, sure. Fecal bacteria, not so much.

But there is a small group of experts who have been keeping a close eye on potentially harmful bacteria at the beaches for decades.


Every Monday morning, as the sun begins to emerge and glisten over the waves along Delaware's coast, a small team of scientists race from beach to beach to collect water samples that will reveal whether the beaches are safe for the pending influx of visitors.

Led by Michael Bott of the Delaware Department of Natural Resources and Environmental Control, those scientists are looking for the presence of bacteria that could indicate the potential to make vulnerable beachgoers ill.


"The public health criteria and actual risk is based off human sewage, but the indicator is enterococcus, which grows in the guts of any warm-blooded animal," Bott said. "In Delaware, our primary source for fecal bacteria is wildlife."

Those experts have a few hours to pull samples from 23 coastal locations between Slaughter Beach and Fenwick Island before dropping them off at a University of Delaware laboratory in Lewes. On Wednesdays, they return for a second round of testing at Delaware's busiest beaches, which are Cape Henlopen State Park, Rehoboth Beach, Dewey Beach, Bethany Beach and Fenwick Island.

Enterococcus is not what makes people sick, Bott said, but rather is an indicator that bacteria that can cause gastrointestinal illness or distress could be present.

When it is found — like it was recently at Slaughter Beach due to an influx of defecating shorebirds — Bott's team issues a public advisory. Those go out to an email list that people can sign up for online, and are also available with more details through an online interactive map.

Those advisories are not beach closures. They're just a warning that elevated levels of bacteria are present. It's up to the individual beach towns to make the call to limit contact with the water, Bott said.

DNREC also periodically tests freshwater swimming beaches such as Lake Como in Smyrna.

When higher levels of bacteria are detected, it generally does not pose a problem for most healthy people who don't plan on chugging the water. But high levels can cause gastrointestinal distress if ingested by sensitive groups like the young, old and ill.

Those state advisories also usually contain background information about recent rain events or large groups of birds to offer insight into the likely cause of the higher bacteria levels. Beaches under advisory are retested as often as possible until those levels return to normal, Bott said.


"It's part of that natural system," Bott said. "You can't fight it."

Edward Whereat, a scientist at the University of Delaware's pollution ecology laboratory in Lewes, said studies have shown that fecal indicator bacteria in Delaware's waterways often comes from wildlife sources, like the birds at Slaughter Beach. That means it's less likely that an otherwise healthy person would get sick — but there's always a risk.

The human-based bacteria would pose a much higher threat, like it did when experts found that people visiting beaches near sewage plants in the late 1960s and 1970s did get sick from ingesting fecal bacteria, he said.

"Now we have more levels of treatment and we sterilize the effluent, so it is unlikely that bacteria from our sewage systems are getting into the water, except if there are problems," Whereat said. "When ocean beaches get high bacteria readings, it is likely to be birds. The solution there is to do genetic testing, where you try to isolate whose bacteria is whose."

It is possible to track the source of that fecal bacteria and possibly do it in a quicker turnaround time, but would cost 10 to 50 times more than the testing used today, Whereat said.

"For 75 years, there's been this long history of it and it has been an effective tool," he said. "It's cheap, it's easy and we understand it. . . . Maybe in 10, 20 years all this will change."


For now, experts rely on growing the bacteria taken from coastal waters in a laboratory.

"You're not going to be able to see a number on your cellphone as you drive to the beach that day, but you might see what it was for the week or the season," Whereat said. There is some uncertainty and estimating involved in this work, but the methods have been working in getting a clear picture of the bacteria at the beaches, he said.

As the weather begins to warm near the Delaware beaches, a loud clang sounds on the rooftop of the small laboratory near the Roosevelt Inlet in Lewes at which Whereat works. The jarring sound provides a stark contrast to the quiet, clean workspace, but Whereat doesn't even register the noise.

Scientists know that sound means it is low tide. Large gulls take to the sky to drop their shellfish catches onto the flat roof, hoping to reveal the meaty goodness inside.

It's just another day at work for Whereat, who — along with colleagues and interns — runs dozens of samples every summer for state officials to monitor bacteria levels at the state's the most popular swimming beaches.

It's here that DNREC employees deliver those samples, which take about 24 hours to culture. Those cultures release a robin's egg fluorescence that indicates the presence of bacteria. The testing used at the lab can then estimate the concentration in a sample to predict if it's over the federally mandated safe limit for people to immerse themselves from head to toe.


"It's an indicator of fecal contamination," he said. "And other pathogens, if they're present, would correlate with that."

Whereat also oversees the university's Citizen Monitoring Program. It relies on local volunteers to collect samples that feed a database revealing the real-time health of the state's waterways. Separate from the state's recreational water monitoring program, UD's citizen science project collects data throughout the year at places not meant for swimming.

Inside humans and other warm-blooded animals, enterococci are good, for the most part. They help digest food — and each person delivers more than 100 million of these bacteria into their toilet every day, Whereat said.

The program to test Delaware's recreational waters is supported by federal grant money through the BEACH Act of 2000 and is meant to monitor these waterways and then advise people when bacteria is detected. Delaware gets just over $200,000 a year for the program, and other coastal beaches and those along the Great Lakes are also eligible for funding.

"Having good data everywhere, it's a basic environmental right," said Collin O'Mara, president and CEO of the National Wildlife Federation and a former DNREC secretary. "You should know the water in the stream in your backyard or beaches is safe and healthy for your family to go into."

Both Bott and Whereat encourage people to look at the average mean of bacteria levels at these beach sites for a better picture of the risk, rather than relying solely on individual advisories.


That's for a good reason. Those individual advisories aren't available until the day after the sample is taken, and conditions can vary wildly in a matter of days.

At some inland waterways, such as the Inland Bays and canals, brown signs offer a never-ending advisory for the presence of bacteria — which includes everything from those fecal indicator bacteria to the inaccurately dubbed flesh-eating bacteria called Vibrio vulnificus.

Bott and Whereat also encourage people to be aware of how rain events can wash bacteria into nearshore waters, whether directly from rain falling on the beach or piers, or from the discharge of stormwater into the ocean in places like Rehoboth Beach.

"With more people and more pollution and more extreme weather, warmer temperatures and more runoff, we just have to do everything we possibly can to protect the beach water quality," O'Mara said.

The bigger debate is how to keep the water clean, he said. "We have good data. Now we need more investment."

U.S. Sen. Tom Carper said ensuring water quality at Delaware's beaches is key to the state's economy and the $7 billion impact of coastal tourism.


"This success relies in large part on our beaches' reputation and the public's confidence that our coastal waters are safe for swimming and other recreational activities," he said. "This federal funding will boost state and local efforts to ensure we have clean coastal waters, helping to prevent threats to public health and costly beach closures during the busy summer season."

That's why you shouldn't feed leftover Thrasher's fries to the gulls. And why it's important to pick up that dog poo. No one wants poop bacteria where they wade.

For more about the testing at Delaware's beaches, go to or call 800-922-WAVE.

For more information about UD's Citizen Monitoring Program or to become a dedicated, longtime volunteer (volunteers are most needed in the area of Massey's Landing and north Rehoboth Bay), go to

What other beach curiosities would you like to learn about? Contact reporter Maddy Lauria at (302) 345-0608, or on Twitter @MaddyinMilford.