Bacteria Levels in Sligo Creek

WSSC Analysis of Monitoring, December 2011

WSSC made a presentation about the results of the monitoring through 2011, which can be found here. A preliminary qualitative observation is that 80-100% of the bacteria sources in area streams has been found to be pets, wildlife, and agriculture, and the predominate source avian/waterfowl. Note regarding the comment in slide 4: Suggestions from AWS considered: Reduce sampling points outside Anacostia watershed. Emphasis on the word points. The complete suggestion was to reduce the sampling points and double the monitoring frequency at those stations, leaving the actual number of times monitoring was done unchanged at those stations.

WSSC Monitoring Results, 2007-present

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 so far for Sligo Creek:

DateSligo Upstream Site RankingFecal Bacteria Results
Enterococcus CFU/100mL
Sligo Downstream Site RankingFecal Bacteria Results
Enterococcus CFU/100mL
December 15th, 201625th/40 sites tested28229th/40 sites tested419
March 23, 201615th/40 sites tested161st/40 sites tested
(tied with thirteen other sites)
September 15th, 201532nd/40 sites tested51025th/40 sites tested283
March 19th, 20151st/40 sites tested
(tied with 15 other sites)
<1029th/40 sites tested45
September 17th, 201436th/40 sites tested43312th/40 sites tested71
April 2nd, 201423rd/40 sites tested6924th/40 sites tested71
September 18th, 201338th/40 sites tested9529th/40 sites tested85
March 28th, 201319th/40 sites tested1825th/40 sites tested31
October 18th, 201220th/40 sites tested16229th/40 sites tested273
April 4th, 201233rd/40 sites tested8335th/40 sites tested102
November 2nd, 201116th/40 sites tested1259th/40 sites tested70
June 4th, 2011N/AN/A4th/4 sites tested370
March 29th, 201127th/40 sites tested3839th/40 sites tested825
November 10th, 2010N/AN/A3rd/4 sites tested39
October 12th, 201018th/40 sites tested32310th/40 sites tested213
June 28th, 2010N/AN/A4th/4 sites tested2720
April 13th, 201018th/40 sites tested231st/40 sites tested
(tied with six other sites)
November 18th, 2009N/AN/A2nd/4 sites tested39
September 21st, 200939th/40 sites tested84840th/40 sites tested877
June 26th, 2009N/AN/A4rd/4 sites tested187
March 24th, 200935th/40 sites tested7829th/40 sites tested23
November 19th, 2008N/AN/A4rd/4 sites tested57
September 17th, 200827th/40 sites tested30835th/40 sites tested483
July 9th, 2008N/AN/A3rd/4 sites tested50
March 26th, 20081st/40 sites tested
(tied with 25 other sites)
<1038th/40 sites tested90
January 9th, 2008N/AN/A4th/4 sites tested328
September 20th, 200735th/40 sites tested72032nd/40 sites tested550
June 25th, 2007N/AN/A4th/4 sites tested635
March 28th, 200737th/40 sites tested17935th/40 sites tested113

The Maryland state standards for Enterococci bacteria:
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


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