can the camping sites accommodate a 30 foot trailer, and is there a dump station?

yes, there is a dump station. 30ft will be tight in most sites. if you do not have a reservation, get there early (7:00am) Camp hosts will try hard to make a good match for non-reservations.

There is a dump station. 30ft should fit in most. It might be a little tight, however last time I was there we were right next to a big rv, prolly 45 ft, they had room to spare.

You could probably fit one in a couple of the spaces there but would have to disconnect the tow vehicle. I don't know if they have a posted length limit. Yes there is a dump station

Yes, they have a dump station and can accommodate a 30ft trailer. It will be tight though. They do not have hookups either unless you stay at Watchman.