Locations of urban CZ sites. Red indicates > 50% impervious‚Ä® surface area.
Urban CZ study watersheds: Pennypack Creek, Philadelphia, PA; Dead Run subwater- shed of the Gwynns Falls, Baltimore, MD; NW Branch Anacostia, Washington, DC (MD); Difficult Run, Washington DC (VA); Swift Creek, Raleigh, NC. Locations along Fall Zone are shown in Figure 1. Color key: white: 0 – 15% ; pink: > 15% – 50%; red: > 50% impervious surface area. Green triangles indicate USGS stream gage locations; blue lines indicate hydrography; black lines show boundaries of watershed areas draining to stream gages.