Here is a link to a most excellent interactive tool that shows the danger of the sometimes placid looking waters below Great Falls of the Potomac River. Kudos to Sohail Al-Jamea, Bonnie Berkowitz, Emily Chow, Laris Karklis and Todd Lindeman for the design and development of this excellent online tool. Also see and read the related story In the Potomac’s grip: The deceptively placid waters at Great Falls by Steve Hendrix.
Sources
Brent O’Neill, National Park Service site manager at Great Falls Park; Steve Taylor, an engineer and investigator for a 1992 Maryland Department of Resources study of Potomac hydrology; USGS geologist Scott Southworth; USGS hydrologist Jonathan Dillow; Fairfax County Fire and Rescue’s swift-water team; Jason Beakes and Gil Rocha of the Potomac Paddlers Volunteer Corps; American Whitewater. Published Aug. 10, 2013