"The National Map". National Hydrography Dataset high-resolution flowline data. U.S. Geological Survey. Archived from the original on March 29, 2012. Retrieved May 4, 2011.
"The National Map". National Hydrography Dataset high-resolution flowline data. U.S. Geological Survey. Archived from the original on March 29, 2012. Retrieved May 4, 2011.