Water Quality Conditions

Combined Sewer Overflows (CSOs)
The Anacostia River continues to be adversely impacted by high bacteria levels. General sources of this bacterial contamination include combined sewer overflows, leaking sewers, wildlife, pet waste, and a growing homeless population. The District of Columbia, like many older cities, has a sewer system that combines wastewater with stormwater runoff. Approximately 60 percent of the Anacostia watershed within the District of Columbia drains directly to the tidal Anacostia River via a combined sanitary and storm sewer system dating back to the late 1800's. There are 11, active major combined sewer outfalls to the Anacostia River and all discharge in the vicinity of the East Capitol Street and South Capitol Street bridges.
During normal dry weather conditions, all of the sewage in these combined sewers is processed by the Blue Plains Wastewater Treatment Plant. During small to medium rainstorms, however, the combined sewer system reaches its capacity and overflows of mixed untreated sewage and stormwater runoff enter directly into the Anacostia, the Potomac or Rock Creek at the 59 CSO outfalls located along those waterways. According to DCWASA, in an average year, there are approximately 82 overflow events in the Anacostia River, 75 in the Potomac River, and 30 in Rock Creek. On average, overflows result in an estimated 1.3 billion gallons of sanitary waste discharged per year into the Anacostia River.
CSO's are the primary point sources, accounting for approximately 61 percent of the bacterial loadings, degrading the Anacostia River's water quality. However, only about 14 percent of the annual, biochemical oxygen demand (BOD5) pollutant loadings to the Anacostia River are from CSO's compared to about 86 percent from upstream nonpoint sources and D.C. stormwater. Figure 36 shows the relative BOD5 load contributions from various parts of the watershed.

Dissolved Oxygen Levels-Organic Loadings
Stormwater runoff, combined sewer overflows, leaking sewer lines, as well as natural processes, all contribute significant amounts of organic matter to the Anacostia River. Organic matter, which refers to anything derived from living organisms, must then be broken down or decomposed by microorganisms within the river. Depending on the timing and size of the load, the decomposition of this material can require a substantial amount of oxygen. One measure of the amount of oxygen required to decompose organic matter (principally organic carbon) over a fixed amount of time (typically 5 days) is termed the five-day biochemical oxygen demand (BOD5). While BOD5 does not account for the total oxygen demand to a water body, it does provide a good representation. When characterized as a pollutant load, BOD5 is expressed in terms of the total organic load to a receiving waterbody that is biologically oxidizable.

Trash and Debris
It has been estimated that over 20,000 tons of trash and debris enter the Anacostia River annually. While the actual load to the river is unknown, without question, trash remains one of the watershed's most highly visible and aesthetic problems. Trash and non-woody debris, entering the watershed's tributaries and tidal river largely through urban storm drain systems, can have chemical and biological impacts on receiving waters including: interference with the establishment of aquatic plants, leaching of toxics from certain types of trash such as used oil quart containers and batteries, and floating trash hazards to wildlife through ingestion of or entanglement in floating debris. The types of trash and debris and the sources are many, making the management of this ubiquitous problem, quite challenging.
In 1992, the Floating Debris Removal Program for the Anacostia and Potomac Rivers was developed by the District of Columbia Department of Public Works as a pilot project to address debris control problems intrinsic to the tidal Anacostia River. These control problems include: relatively low flow rates and long turnover times of approximately 90 days in flushing out debris, many stormwater and CSO outfalls, and many mudflats and deltas exposed at low tides, all of which tend to retain debris. While the collection of trash and debris does not address nor begin to control the sources of the problem, it does provide a means for quantifying it.
The District of Columbia Water and Sewer Authority (DCWASA) which now runs the debris removal program removes, with its skimmer boat fleet, an average of 500 tons of trash and debris per year. The increase in the tonnages removed after 1993 are partly attributable to additional trash and debris collecting equipment.
Starting in 1998, approximately 15 miles of the Anacostia tributary system along with a four- mile-long portion of the upper tidal river area have been surveyed for trash every year by both COG and citizen volunteers. It should be noted that efforts to fill in the data gaps that exist in the baseline stream trash level dataset have intensified since 2006, when both Maryland and the District of Columbia listed the Anacostia River as impaired for trash under the Clean Water Act.