The Potomac River (image) University of Maryland Share Print E-Mail Caption Alkaline minerals wash down from headwater streams and tributaries of the 14,700-square-mile Potomac River watershed to Washington D.C., where the river provides the nation's capital with drinking water and receives treated sewage before emptying into the Chesapeake Bay. High alkalinity can make drinking water treatment more expensive, adds to the regulatory requirements for discharging treated sewage, and compounds the environmental problems of the nation's largest estuary. Credit Photo: Michael Pennino Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.