U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived 2017-08-23 at the Wayback Machine, accessed March 29, 2011
U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived 2017-08-23 at the Wayback Machine, accessed March 29, 2011