Connect the Drops

Protecting the Potomac

Potomac River water flows to the faucets of 6 million people, making the Nation’s River the lifeblood of our Washington, D.C., metropolitan area. Ensuring clean water means keeping a close eye on what goes into our waterways. Reducing polluted runoff - from farm fields and cities - is one of the best ways to protect clean water.


Thanks to our many partners and supporters, The Nature Conservancy has helped protect roughly 40,000 acres throughout the Potomac watershed, starting at the river’s headwaters in West Virginia and including tributaries like Sideling Hill and Nanjemoy creeks in Maryland. This network of Conservancy preserves, public parks, working farms and forests helps maintain clean water for people to drink and for healthy habitats in the Potomac and downstream in the Chesapeake Bay.

The Potomac is the second-largest source of fresh water feeding into the Chesapeake Bay. Securing clean water for the river is integral to restoring a healthy bay. The good news is that the Potomac watershed is more heavily forested today than a century ago. These forests produce tremendous benefits for clean water, helping to absorb excess nutrients and sediments from agricultural and urban areas that otherwise would flush into the river, causing harm to wildlife and threatening the security of our drinking water.


Stormwater - polluted runoff from urban and suburban lands - is the only growing source of pollution to the Potomac River and the Chesapeake Bay. Stormwater carries pollution from paved surfaces - including roads, parking lots, and driveways – as well as from residential lawns and golf courses; pet and wildlife waste; and construction activities into our area’s streams and rivers like the Anacostia, Rock Creek, and Potomac. The growing population in our region means more paved surfaces, and more challenges for clean water.

An additional problem for clean water is posed by old water pipe systems, like that found in Washington, D.C. These “combined” sewer systems convey both sanitary sewage and storm water in one piping system. All of their wastewater is delivered to a sewage treatment plant, where it is treated and then discharged to a water body. But in times of heavy rain, the capacity of the system is overloaded and the mixture of raw sewage and stormwater flows right into the river, untreated.

By replacing pavement with green infrastructure —features like trees, rain gardens and constructed wetlands that capture and filter polluted stormwater — the Conservancy is working to facilitate cost‐effective, environmentally sound stormwater management. These installations clean our urban waterways and help lower stormwater management costs, while simultaneously improving the quality of life for local communities through the reduction of heat islands and improved air quality. The Conservancy is identifying a green infrastructure pilot site in D.C., with a goal of breaking ground by early spring 2016.

The project is being launched in conjunction with NatureVest, the Conservancy’s impact investment unit, which uses private capital to fund conservation projects. New regulations under D.C.’s Stormwater Management Plan focus on using a market-based approach to spur green infrastructure development, including green roofs, bioretention cells and wetlands. The regulations are the first of their kind and may shape how several urban centers approach stormwater in the future.

Your support will help us achieve our goals of restoring urban waterways and maintaining our supply of clean water far into the future. Together, we can protect the Potomac River from the Central Appalachians to the Chesapeake Bay.

The Nature Conservancy’s pragmatic, science-based programs and partnerships help keep water clean and accessible, here and around the world. Connect the drops between clean water, The Nature Conservancy and you. Visit