U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived 2012-03-29 at the Wayback Machine, accessed December 28, 2017
U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived 2012-03-29 at the Wayback Machine, accessed December 28, 2017