A SNAPSHOT OF POTOMAC WATERSHED HEALTH
- Of approximately 10,000 stream miles assessed in the watershed, more than 3,800 miles were deemed “threatened” or “impaired”.
- The Potomac is one of the least dam-regulated large river systems in the eastern United States.
- The Potomac has the highest level of nitrogen and the third highest level of phosphorus of all the major rivers in the Chesapeake Bay watershed. These nutrients can limit the growth of submerged aquatic vegetation, cause low oxygen conditions and create deadzones.
- Approximately 90% DC area drinking water comes from Potomac.
- Between 1986 and 1999, Maryland averaged more than 6,000 acres of forest loss per year. Forests are capable of capturing up to 6 times more rain than grass alone and 20 times more rain than impervious surfaces, such as parking lots.
- Over a 30-year period, the tree canopy in Washington, DC has declined by 16% and the stormwater runoff has increased by 34%.
- Swimming is not an approved activity in the waters of the Potomac and Anacostia in the District of Columbia.
- Effluent from wastewater treatment plants is currently the most notably identified point-source contribution of endocrine disrupting contaminants in the Potomac River.
- Emerging contaminants in the Potomac include personal care products, pharmaceuticals and over-the-counter medications, agricultural pollution, animal feedlots, industrial byproducts, and biosolids.
- In the last three decades, many areas in the watershed have seen their population more than double. A growing population alters and stresses the natural state of its land and water.
- The Potomac watershed is expected to add more than 1 million people to its population over the next 20 years.
- The most densely populated area in the watershed is the Middle Potomac, including Washington, DC, which is home to 3.72 or about 70% of the watershed’s population.
- In the next 20 years, the population of the Potomac watershed is expected to grow 10% each decade, adding 1 million inhabitants to reach a population of 6.25 million.
- An 80% prevalence of the intersex condition was reported in male smallmouth bass in the Shenandoah and Fork rivers of the Potomac in a 2002 USGS study.
- EPA reviews anywhere from 1500-3000 “new” chemicals annually-- many of which enter Potomac waterways, undetected by wastewater treatment plants.
- The combined sewer system in Washington, DC includes 53 combined sewer overflow outfalls in the Potomac watershed: 10 of which discharge to the main stem, 15 to the Anacostia River, and 28 to Rock Creek and its tributaries.
- Along the Anacostia shoreline, 17 discharge locations result in 2-3 billion gallons of sewage overflow into the river each year.
- The Potomac River delivers the largest amount of sediment to the Chesapeake Bay each year which can limit the growth and submerged aquatic vegetation and affect populations of all fish, shellfish and birds that depend on this vegetation as a source of food or shelter.
Please note: Sources include State of the Nation’s River reports 2007, 2008 and 2009, and the Interstate Commission on the Potomac River Basin. Questions about information sourcing can be sent to Anne Sundermann, Senior Director of Communications & Outreach, sundermann@potomac.org.