How do you dispose of gray water at a site that doesn’t have full hookup sewer?

Yes, the RV sites have full hook ups. Also, just some info, the shower/bathrooms are some of the best I've seen at any RV campground. These can be useful especially when multiple people need to get ready early in the morning to go to the parks.

All of the sites I've seen at fort wilderness have full hookup sewer but at other camps I've been to they'll have a sewage receptacle somewhere and you use a tote-like thing on wheels to move black and gray water.