Do you have to stay at the campground in order to visit the park or are there seperate prices?

No you don't but you still need to go to the office for a visitor pass.

The campground is about a 20 minute drive from the park. They are not associated with each other and have separate fees.

They have single day passes for pool

You do not have to camp here. Guest passes are $12.72 per day per person to use the swimming pools, splash Park and water slides. If you also want the wrist band for the other activities including bike rental, boat rides, bumper boats, paddle boats, aqua trikes, mini golf and jumping pillow, the charges is another $12.72 per person.