WSSC Monitoring – Results Analysis

WSSC Analysis of Monitoring, December 2011

WSSC presented the results of their water quality monitoring through Dec 2011, pursuant to the consent degree. A preliminary qualitative observation is that 80-100% of the bacteria sources in area streams has been found to be from pets, wildlife, and agriculture, and the predominate source, avian/waterfowl. A note regarding the comment in slide 4: “Suggestions from AWS considered: reduce points outside the Anacostia watershed.” The complete suggestion was to reduce the sampling points and double the monitoring frequency at certain stations, leaving unchanged the actual number of times monitoring is done.

WSSC Monitoring Results, 2007-2016

As a result of the consent decree, the Washington Suburban Sanitary Commission (WSSC) began monitoring regional waterways for levels of fecal bacteria, including bacteria source testing. Here are the results through 2016 for Sligo Creek:

Date Sligo Upstream Site Ranking Fecal Bacteria Results
Enterococcus CFU/100mL
Sligo Downstream Site Ranking Fecal Bacteria Results
Enterococcus CFU/100mL
December 15th, 2016 25th/40 sites tested 282 29th/40 sites tested 419
March 23, 2016 15th/40 sites tested 16 1st/40 sites tested
(tied with thirteen other sites)
September 15th, 2015 32nd/40 sites tested 510 25th/40 sites tested 283
March 19th, 2015 1st/40 sites tested
(tied with 15 other sites)
<10 29th/40 sites tested 45
September 17th, 2014 36th/40 sites tested 433 12th/40 sites tested 71
April 2nd, 2014 23rd/40 sites tested 69 24th/40 sites tested 71
September 18th, 2013 38th/40 sites tested 952 9th/40 sites tested 85
March 28th, 2013 19th/40 sites tested 18 25th/40 sites tested 31
October 18th, 2012 20th/40 sites tested 162 29th/40 sites tested 273
April 4th, 2012 33rd/40 sites tested 83 35th/40 sites tested 102
November 2nd, 2011 16th/40 sites tested 125 9th/40 sites tested 70
June 4th, 2011 N/A N/A 4th/4 sites tested 370
March 29th, 2011 27th/40 sites tested 38 39th/40 sites tested 825
November 10th, 2010 N/A N/A 3rd/4 sites tested 39
October 12th, 2010 18th/40 sites tested 323 10th/40 sites tested 213
June 28th, 2010 N/A N/A 4th/4 sites tested 2720
April 13th, 2010 18th/40 sites tested 23 1st/40 sites tested
(tied with six other sites)
November 18th, 2009 N/A N/A 2nd/4 sites tested 39
September 21st, 2009 39th/40 sites tested 848 40th/40 sites tested 877
June 26th, 2009 N/A N/A 4rd/4 sites tested 187
March 24th, 2009 35th/40 sites tested 78 29th/40 sites tested 23
November 19th, 2008 N/A N/A 4rd/4 sites tested 57
September 17th, 2008 27th/40 sites tested 308 35th/40 sites tested 483
July 9th, 2008 N/A N/A 3rd/4 sites tested 50
March 26th, 2008 1st/40 sites tested
(tied with 25 other sites)
<10 38th/40 sites tested 90
January 9th, 2008 N/A N/A 4th/4 sites tested 328
September 20th, 2007 35th/40 sites tested 720 32nd/40 sites tested 550
June 25th, 2007 N/A N/A 4th/4 sites tested 635
March 28th, 2007 37th/40 sites tested 179 35th/40 sites tested 113


The Maryland state standards for Enterococci bacteria are:

All Areas:  33
Frequent Full Body Contact Recreation:  61
Moderately Frequent Full Body Contact Recreation:  78
Occasional Frequent Full Body Contact Recreation: 107
Infrequent Full Body Contact Recreation: 151

All numbers are counts per 100 milliliters


2004-2005 Water Quality Testing

The Anacostia Watershed Society’s Water Quality Specialist Masaya Maeda conducted bacteria testing of Sligo Creek. This important work led to the WSSC’s present monitoring.