Wow, RIP Dorney Park, I guess.
Well, they did officially come out and say that Wildwater Kingdom wasn't opening with Dorney Park's rides on the 8th, but haven't ruled it out completely. CF also owns (and operates?) those two Schlitterbahn parks in Texas, and they've been open since the middle of June.
In states where masks are not mandated, staffing is probably a major issue more than anything else. Figure 2 lifeguards per pair of slides, not to mention the 10 at the wave pool and who-knows-how-many for the lazy river, then you have all of the food service stands...it all adds up. In states that have said "if you're in a public place you have to wear a mask," then waterparks are a non-starter.
Noah's Ark was full this weekend, White Water in Branson and Big Surf in the Ozarks have opened, they don't recommended masks in the water