Bacteria Data

2014 Operation Clearwater Results


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The South River Federation is a participant in Operation Clearwater, a bacteria testing program for community waterfront recreational areas on the South River that runs from May through Labor Day. The program provides waterfront communities on the South River with regular updates of the microbial water quality at their waterfront recreational areas. Operation Clearwater was started by the Severn River Association and is a collaborative effort with Dr. Sally Hornor, a Professor of Microbiology at Anne Arundel Community College, aimed at providing timely public health information to participating communities and helping to identify times when it may be inadvisable to swim.

Note: The Anne Arundel County Health Department advises that after a rainfall, all Anne Arundel County beaches are under a no swimming/no direct water contact advisory for 48 hours due to predicted elevated bacteria levels from rainwater runoff and increased health risks.

2014 Bacteria Results: (Greater than 104 cfu/100 ml are considered elevated bacteria levels.  These samples are highlighted in red)

Have Your Swimming Area Sampled:

OPERATION CLEARWATER monitors water quality by enumerating a group of bacteria collectively known as the Enterococci. These bacteria, like the fecal coliforms counted in the past, are associated with fecal waste of warm-blooded animals, birds and mammals. These bacteria themselves are not harmful to swimmers but they do indicate the presence of recent fecal contamination of water. When the number of Enterococci exceeds 104/100 ml, there may be other microorganisms present in the water which could cause illness, such as gastroenteritis or ear infections. It is generally recommended by the U.S. Environmental Protection Agency not to swim in water containing enterococci counts that have an average value exceeding 35/100 ml or a single sample result of more than 104/100. Thus counts that exceed 104/100 ml are highlighted in red on our web site. For more information about the EPA method and interpretation of results, visit this EPA document. The counts of bacteria in water are always variable. The number of Enterococci/100 ml will vary greatly depending on rainfall. Once we have received enough rain to cause substantial overland flow into our creeks and rivers, generally about one-half inch of rain, bacterial counts will tend to rise sharply and will remain high for 24-48 hours. This is especially true in areas where runoff flows down streets directly into creeks and rivers. For this reason, rain data are included in this report when we have had at least 0.5" of rain within the watershed 24-48 hours previous to sample collection. Of course, summer thunderstorms are notoriously spotty. As we measure rainfall in Annapolis, a brief but intense storm in Crownsville or Edgewater may not even be recorded.

Samples are collected on Wednesday mornings between 7 am and noon at a location of your choosing at the community's waterfront facility. If you do not specify where to sample, Federation staff will use best professional judgment to sample the community swimming beach. Data are posted at the Federation website by Friday morning. If the number of enterococci exceeds 104/100 ml, Operation Clearwater Community Representatives are notified promptly by phone or email.

A 14 week schedule costs $385 and runs from mid-May through August.

Contact the Federation office at 410-224-3802 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it us for more information or to sign up for sampling.

Click here for the application.


2011 Bacteria Results:


What does this mean?

Over 70% of the sites sampled in 2010 passed the EPA threshold for Enterococci bacteria (<104 cfu/ml).  The vast majority of the samples that failed were taken on July 14th and August 18th, both within 24 hours of a 1"+ rain event, which tends to worsen bacteria outbreaks.   Two sites, Pine Whiff (Almshouse Creek) and South River Park (Warehouse Creek), did have persistent bacteria problems, but even without that data, there were several spikes during rain events.

Past Bacteria Sampling Results:

2011 Data [pdf]

2010 Data [pdf]

2009 Data [pdf]

2008 Data [pdf]

2007 Data [pdf]

2006 Data [pdf]

2005 Data [pdf]

2004 Data [pdf]


Attention New Survey!  Click here to read the entire letter from Capt. Diana Muller, Director of Science and South RIVERKEEPER┬« regarding water-related illnesses.  Click here to download the 2014 Illness Tracking Sheet.