Hydrologic Unit : A geographical area representing part or all of a surface drainage basin or distinct hydrologic feature such as a reservoir, lake, etc
National Weather Service NWS Forecast Office, National Oceanic and Atmospheric Administration NOAA, SH Manual, Glossary of Hydrologic Terms, Washington, DC, USA 2015. http://www.nws.noaa.gov/om/hod/SHManual/SHMan014_g lossary.htm, (HydroI - Amer) {889}