Enterococcus 2017-11-29T08:19:55+00:00

What is Enterococcus?

“Enterococcus is a bacterium that’s common in rainwater runoff. It’s found in the gut of mammals so typically what occurs is after periods of heavy rain, cattle waste, pet waste and some sewage overflows will get washed off the land and into rivers, and streams and eventually into larger bodies of water,” said Scott Packard, Director of Communications with the Galveston County Health District. 12 News

Enterococcus is another fecal indicator bacteria that could potentially cause harm to people who come into contact or ingest them while in the water. It can cause urinary tract infections, bacteremia, bacterial endocarditis, diverticulitis, and meningitis.

Enterococci, along with E. coli, are used to test for water contamination. The U.S. EPA finds enterococci as a very good predictor of illness in all waters. The regulatory body had recommended the use of enterococci for water quality monitoring in fresh and marine recreation waters.  E. coli, on the other hand, is recommended for fresh recreational waters.

Bacteria counts are measured by the number of colony forming units (cfu) per 100 milliliters of water. The EPA set suitable levels for enterococci in marine waters as 35 cfu/100mL for a 30-day mean and 104 – 501 cfu/100mL for a single sample. In fresh water, the EPA capped the acceptable level at 33 cfu/100mL for a 30-day mean and 61 – 151 cfu/100 mL as a single sample reading.

Enterococci are typically not considered harmful to humans. However, their presence in the water is a red flag for other disease-causing agents such as viruses, bacteria, and protozoa. If a swimmer swims in waters infested with Enterococci, they could develop  diseases of the skin, eyes, ears and respiratory tract. If people eat raw shellfish or fish harvested from waters with fecal contamination, they could also get sick.

Elevated levels of Enterococcus and fecal coliform bacteria in a water body can negatively affect the recreational and economic value of the aquatic resource. It can cause beach closures, swimming and boating bans, and closures of fishing and shellfishing areas. That is why regulatory agencies monitor Enterococcus and fecal coliform in water.  

Reduce Enterococcus in Water

To reduce the amount of Enterococcus down to acceptable levels, water managers must find the source. The EPA cited these examples of enterococci sources:

  • wastewater treatment plant effluent,

  • leaking septic systems,

  • stormwater runoff,

  • sewage discharged or dumped from recreational boats,

  • domestic animal and wildlife waste,

  • improper land application of manure or sewage, and

  • runoff from manure storage areas, pastures, rangelands, and feedlots

But routine water quality testing does not really provide the source of Enterococcus as well as fecal coliform in water.  Enterococci is a group of bacteria that commonly reside in the guts of animals, including humans. So when a test for water contamination detects Enterococcus, the host of the bacteria could come from a myriad of sources. Source Molecular analyzes the DNA of the bacteria to find out if it came from humans, livestock, pets or wildlife.

Source Molecular’s microbial source tracking (MST) services complements and enhances the results of routine water quality monitoring. MST results provide scientific evidence to back remediation efforts.

Successful Enterococcus Projects

Back and Spa Creek Watersheds


The Back and Spa Creek watersheds in Anne Arundel County, Maryland, experienced high levels of enterococci bacteria, particularly in two sampling sites. The water near Chesapeake Children’s Museum and South Cherry Grove Avenue had an overabundance of enterococcus when it was sampled in June and July 2016.

Rhonda Wardlaw at Capital Gazette noted that some people suspected the Enterococcus may come from a sewer leak or spill. This is usually the default assumption made when it comes to water pollution. People reach the same conclusion when the waters are contaminated by fecal coliform bacteria.

The City of Annapolis wanted to see if it was true so they took additional samples from both sites in August 2016 and sent them to Source Molecular for MST analysis. Results came back negative of human fecal contamination. The same conclusion was drawn by the City Utilities Division, which conducted inspections. They could not find any relation between the high bacteria levels to leaks or spills from the city’s sanitary sewer system.

Thus, the city was able to prove they were not at fault for the water contamination.

Tower Road Bayside Beach


Tower Road Bayside Beach in Delaware suffered from consistently high counts of

Enterococcus. The Department of Natural Resources and Environmental Control conducted a source tracking study in the summer of 2011 to address the persistent pollution. The suspected sources of the Enterococci were humans, dogs and seagulls.

A total of 49 samples were collected from May to September 2011 at different locations along the shoreline. Source Molecular and Dr. Jody Harwood of the University of South Florida tested the samples for human and gull DNA. Source Molecular also tested the samples for specific dog‐associated and bird‐associated fecal bacteria.

Seagulls emerged as the main culprit for the fecal contamination. The labs reported that seagull‐associated bacteria dominated in 98% of the water samples while human and dog bacteria were only detected in 19% and 4% of the samples, respectively.

The state was then able to craft plans that targeted the seagulls to prevent them from further contaminating the beach.

Find Enterococcus Sources Now

Where does the Enterococcus bacteria in your waters come from?  Source Molecular can help you find the answer.  Contact us today!