Intersting Graph

Geometric Mean of Fecal Coliform number -2002-

     Explanation

• Compared to the fecal coliform numbers at the monitoring sites on the Potomac River, those on the Anacostia River are high.  The difference is very clear and it reinforces the fact that the Anacostia River has been the recipient of a disproportionate level of pollution.
• Curiously, the numbers for fecal coliform on the Anacostia River are higher at the monitoring site upstream in Maryland than they are downstream in the District of Columbia where there are a high number of CSO outfalls near or around the monitoring site.  (See map below for the location of the sampling sites)  These findings correspond to the WASA report[1] and data from the Anacostia Watershed Society’s ongoing  Water Quality Monitoring & Flagging Project –2003-.
• Possible explanations why the water quality upstream is more contaminated in regard to fecal coliform than downstream include: leakage from sewer pipes, leakage from septic tanks, malfunction of septic tanks, illegal sewer pipe connections,  domestic and wild animal manure, and urban runoff.
• The effect of the tide is another possible explanation for the difference in water quality on the Anacostia River.  The water downstream in the Anacostia is “washed” by cleaner water from the Potomac River coming in as a result of tidal action, and therefore might yield lower levels of fecal coliform.
• Fecal coliform is just one of the many pollution parameters in the Anacostia River.  However, the presence of fecal coliform in the water column indicates  that raw sewage from human activity is a likely contributor to the problem.  Lowering the fecal coliform levels will decrease the burden on the river.

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