U.S. Geological Survey. "The National Map" (National Hydrography Dataset high-resolution flowline data). Archived from the original on March 29, 2012. Retrieved November 21, 2011.
web.archive.org
U.S. Geological Survey. "The National Map" (National Hydrography Dataset high-resolution flowline data). Archived from the original on March 29, 2012. Retrieved November 21, 2011.