This publication is a joint effort of the Maryland Sea Grant College and the Alliance for the Chesapeake Bay, supported by the Chesapeake Bay Program's Toxics Subcommittee

Winding down from the Appalachians, and draining waters from four states and the District of Columbia, the Potomac River – now named an American Heritage River – helps to define the region. The tidal Potomac, from the fall line to the Bay, provides a prime example of the range of water quality conditions found in a single river. From the troubled waters that flow through the densely populated portions of Maryland, Virginia, and Washington, D.C. to the healthier waters of the lower Potomac, a trip down this historic river reveals the kinds of impacts we have had on the rivers that flow to the Chesapeake.

Targeting Toxics: A Characterization Report lists the upper tidal Potomac above the Wilson Bridge as an impaired stretch of river, with elevated levels of PCBs, a variety of metals, and other contaminants that likely derive from diffuse sources such as stormwater runoff. Problems persist in the middle Potomac, the river segment that stretches from the Wilson bridge to just beyond Route 301, near Morgantown, Maryland and Dalgren, Virginia. Both the upper and middle segments of the river are designated as Areas of Emphasis because of the significant potential for contaminant-related problems. In the lower Potomac, the river begins to improve. With the exception of a few localized regions along the southern Virginia shore, there are no indications of elevated levels of contaminants that adversely affect aquatic life. For this reason, the lower Potomac, the largest of the river's three segments, is classified as An Area of Low Probability of Adverse Effects— though some point out that additional data is needed to develop a more detailed and confident characterization. Not every river has been as well studied as the Potomac, and many segments have been designated as Areas with Inconclusive or Insufficient Data.

Management agencies and the public can use the characterization of these rivers as a starting point to identify areas that need monitoring in order to evaluate the effects of contaminants on living resources. Targeting Toxics can also help citizens focus actions on specific goals, such as developing watershed groups to call for better management of chemical contaminants and defining specific pollution prevention goals in local areas.

Credits

Writers: Jack Greer, Merrill Leffler, James Riordon Designer: Sander Rodgers Contaminants and the Chesapeake Bay is a joint effort of the Maryland Sea Grant College and the Alliance for the Chesapeake Bay, supported by the Chesapeake Bay Program's Toxics Subcommittee.