Are the picnic areas open for huge family gathering? About 75 people in August

I think you should call the office and ask directly. Megan in the office was VERY helpful to me on my camping trip there.

There are pavilions available, but I think you need to reserve areas if you have a large group. I'm not sure if either pavilion area would hold 75 seated comfortably at one time though. Maybe with extra chairs and/or tables. Or else you'll be pretty spread out.