Hi folks ..... The board asked about the USGS Elevation-Derived Specifications at their last meeting. You may find it interesting too, so I am sending it along to everyone. Happy Holidays! .....Dan link to spec: https://pubs.usgs.gov/tm/11/b11/tm11b11.pdf link to resource page: https://www.usgs.gov/core-science-systems/ngp/ss/elevation-derived-hydrography-specifications Elevation-Derived Hydrography Specifications - USGS<https://www.usgs.gov/core-science-systems/ngp/ss/elevation-derived-hydrography-specifications> The USGS provides specifications, READ Rules, and additional resources for the acquisition of elevation-derived hydrography (EDH) from distributed 3DEP products for inclusion in the National Hydrography Dataset. www.usgs.gov ----------------------------------------------------------------------- This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion list for all Maine GIS Users. If you no longer wish to receive e-mail from this list, you can remove your name and email address yourself at the this web address: https://lists.maine.edu/cgi-bin/wa?SUBED1=GEOLIBRARY-L&A=1 Or, you may also request that your name be removed by sending email to: [log in to unmask]