U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived March 29, 2012, at the Wayback Machine. Retrieved August 15, 2011
web.archive.org
U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived March 29, 2012, at the Wayback Machine. Retrieved August 15, 2011