Adding image. From the Environmental Protection Agency, source here: https://cfpub.epa.gov/surf/huc.cfm?huc_code=18060003 As a US government publication, it is not subject to copyright protection
(Adding image. From the Environmental Protection Agency, source here: https://cfpub.epa.gov/surf/huc.cfm?huc_code=18060003 As a US government publication, it is not subject to copyright protection)