Also, the Wetland mapper on the NY site is
https://gisservices.dec.ny.gov/gis/erm/. I believe the DEC uses this map so you can get a good idea if you have a wetland or protected water. My take is that there are no extensive designated wetland areas near Keeseville except along the "major" creeks and the Ausable, but many little ones, so you will have to examine the map closely. You may have to deal with rare plants, but the "significant natural communities" designation in my area didn't seem to impact the DEC's response. I would agree with the NRCS guys that the property along the proposed site looks like a designated wetland and you will need to talk directly with the DEC at some point.
Another useful site is
https://gisservices.dec.ny.gov/gis/stormwater/. You can see what that layer of regs may apply. I would talk to a local excavation contractor and get their take. The guys around me had definite opinions about dealing with the DEC and pond size they would build to avoid that.
