The broad goal of the study is to significantly expand data collection at the Northeast Branch Anacostia and Northwest Branch Anacostia to include water-quality sampling and analysis for a wide suite of natural and anthropogenic constituents (nutrients, sediment, metals, bacteria, and organics such as PCBs and PAHs).
Since the late nineteenth century, ecological problems in the Anacostia Watershed have largely resulted from an expanding human population and the associated changes in land use and land cover. The ongoing loss of forest and wetland habitat, alteration of streamflow, increases in nonpoint source pollution, and discharges of combined sewer overflow and industrial waste have all contributed to the decline in the ecological health of the watershed. These shifts in land use patterns over the last three centuries have drastically changed the ecology of the watershed.
The Anacostia Watershed encompasses 456 square kilometers (176 square miles) within suburban Maryland and the District of Columbia, and crosses two major physiographic provinces, the Coastal Plain and Piedmont. The Anacostia watershed is one of the most densely populated watersheds within the Chesapeake Bay drainage basin. The Watershed has undergone many changes through the years, mainly due to the influence of urbanization on the ecosystem. Major restoration efforts began in 1987.
Historically, many industries were based along the banks of the Anacostia River. Over the years, hazardous substances from these industries and other human activities were discharged directly into the river or were washed into the river by runoff. The Watershed also has experienced substantial deforestation and agricultural development, intense and continuous urbanization, industrial development, and significant loss of fringe wetlands and marshes. The River has been severely stressed by the effects of point and non-point source discharges of contaminants brought about by these changes within the Watershed.
This has resulted in significant sedimentation and elevated levels of hazardous substances, including polychlorinated biphenyls (PCBs), pesticides such as chlordane, lead and other heavy metals, and polynucleararomatic hydrocarbons (PAHs) in sediment throughout the 13.5-kilometer run of the Anacostia River. In addition, the lower reach of the River within the District of Columbia is subject to raw sewage discharges from Combined Sewer Overflows (CSO) during rain events exceeding one-half inch. Significant sedimentation during wet weather flows also impacts and deteriorates the river morphology.
Some of these hazardous substances have been found in fish at levels that endanger the health of the fish. Numerous fish in the river exhibit tumors and lesions. In addition, hazardous substances have been found in the fish at levels that may threaten the health of people who eat them. The District of Columbia declared several fish consumption health advisories in the 1990s with restrictions on bottom-feeding species and game fish, and a fish consumption ban for pregnant women and children.
An estimated 90% of the original wetlands in the Watershed have been lost. The Watershed has been designated one of only three of the region's Areas of Concern by the Chesapeake Bay Program due to risk to aquatic life. A fish consumption ban was imposed by the District of Columbia due to PCB and pesticide contamination of fish. Loss of habitat, erosion, sedimentation, flooding, destruction of wetlands, channelization, toxic pollution, decaying older communities and waterfront areas and loss of river-based recreational opportunities such as boating, fishing and swimming all characterize what had become of the Anacostia River and much of its watershed.
This project will collect samples for nutrients, trace metals, organics, including PCB's and PAH's, bacteria, and suspended sediment at the Northeast and Northwest Branches of the Anacostia River on a monthly basis, and during storm events using automatic sampling equipment. Additionally, continuous water-quality data will be collected, including water temperature, specific conductance, dissolved oxygen, turbidity, and pH.
In subsequent project years, once adequate samples have been collected, the measured nutrient concentration values will be related to concurrent values of continuously measured parameters (water temperature, specific conductance, turbidity, pH, and dissolved-oxygen content) to estimate nitrate, total nitrogen, total phosphorus, and suspended-sediment concentrations in the stream water at 15-minute intervals. The load for each time interval will be calculated by multiplying the estimated concentration by the discharge for the interval computed from the stage-discharge relation established for the site. Total loads for any given period of time can be calculated by summing the loads computed for each measurement interval during the specified period.