By Bradley Kennedy
Nash Run is one of the dirtiest streams in the Anacostia River watershed. However, thanks to D.C’s 5-cent disposable bag fee, one major source of pollution is finally on the decline.
“Astronomical levels of trash” and “dirtiest of all streams” -- these are phrases used to describe the humble little Nash Run, a small tributary of the Anacostia River. Nash Run starts in Fairmount Heights, MD, and runs through the Deanwood neighborhood of DC before emptying into the Anacostia near the Kenilworth Aquatic Gardens. It is one of the biggest contributors of the litter pollution impairing the Anacostia River. But a study on this stream over the past 4 years offers hope that the litter problem can be reversed.
Before the bag fee, and for a short time after, the number of bags in the Anacostia seems to have actually been increasing. Data from a 2007-2008 yearlong survey by the District Department of the Environment show that the total number of bags found in eight tributary streams doubled in a single year. Of course, the absolute numbers of bags (and all litter) varies a lot depending on the weather, but this survey showed an increasing trend:
Chart from Anacostia River Trash Reduction Plan, referring to monitoring study results from Summer 2007 to Spring 2008, before the bag fee. “Number” is the total # of plastic bags found during surveys of 8 stream tributaries of the Anacostia River.
In 2009, the Anacostia Watershed Society installed a trash trap on Nash Run and began collecting data on the types of trash it collected. The trash trap is a special device placed in the stream that allows water to pass through, but catches litter. Once a month for the past four years, volunteers have cleaned out the trap and counted the number of bottles, styrofoam, bags, and other debris.
The amount of trash collected depends on how much rain has fallen during the month -- heavy rainfall carries more trash to the stream and thus the trap. So in order to have a more objective measure of the change in plastic bag use, we use the number of bags found compared to the total amount of trash collected -- expressed as bags per kilogram of trash.
As you can see, similar to the DDOE chart above, this chart also shows an increasing trend in plastic bag litter from March 2009 to June 2010. However, the overall trend is a decrease in plastic bags polluting the stream over the 3-year period after the bag fee was implemented, from January 2010 to November 2012. Why didn’t decline didn’t start immediately after the bag went into effect? We can see several reasons why this might be the case: First, about one third of the Nash Run watershed is actually in Prince George’s County, MD, where there is no bag fee. So, the number of bags entering the stream from Maryland was presumably still increasing according to that 2007-2009 trend. Secondly, it takes time for litter to make its way from neighborhood streets to local streams. Third, compliance and understanding of the bag fee was not 100% right away. So, it’s not too surprising that the number of bags in the stream didn’t drop immediately.
What is clear is that the number of bags is declining, and that this decreasing trend matches the experience of other stream cleanup groups in the DC region. The Alice Ferguson Foundation, which runs cleanup events throughout the Potomac watershed, reported a 50% decline in plastic bags in Montgomery County in the first year after the the Montgomery bag fee went live. The faster decrease may be due to a faster adoption rate in Montgomery County and streams that are fully within the county, unlike Nash Run.
The Anacostia Watershed Society will continue to tally monthly data from the trash trap on Nash Run. Based on these initial results, we expect to see the decline in plastic bags continue, especially if Prince George’s County and/or the state of Maryland implement their own 5-cent bag fees.
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