U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map (Archived 2012-03-29 at the Wayback Machine), accessed October 5, 2012
web.archive.org
U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map (Archived 2012-03-29 at the Wayback Machine), accessed October 5, 2012