Fishing guides on the Upper Delaware River fall under the juristiction of three and sometimes four government agencies. The first three are the states of New York and Pennsylvania, and the National Park Service. The fourth is the US Coast Guard if the guide uses any type of motorized vessel on the main stem of the Delaware River.
There is no reciprocity for guide licenses between NY and PA, so fishing guides must be licensed by both states whenever they are guiding within the boundry waters. These waters include the Delaware River which is entiely boundry water and also National Park Service Water so add in a National Park Service required authorization. The West Branch is aproximately half border water so both states licenses are required by a guide on this lower section of the West Branch. The East Branch of the Delaware is entirely under NY juristiction so only a NY state guide license is required on that river.
Professioanl guides will not guide or take clients on water they are not licensed for. To help the angling public know what guides are licensed where, each of the three entities, NY, PA & the NPS maintain a website that supplies that information.
New York
Pennsylvania
National Park Service
Because someone is licensed in one juristiction doesn't necessarily mean they are licensed in all. Pennsylvania and the National Park Service have strict insurance requirements. New York doesn't, so it's a good idea to ask for an insurance certificate from a NY only licensed guide to be sure you as a customer would be covered in the event of any injury or property loss.
Sure, it can get a little confusing but try to keep it simple by just remembering that a fishing guide needs to be licensed by each state he is guiding in and the National Park Service on NPS water. When PA is one side of the river and NY the other, both states licenses are required by the guide. If on the main stem of the Delaware, both states and the National Park Service. I guess I could have left out the first three paragraphs and said it that way to begin with.