I'd you want to have a party there do you have to pay?

You don't have to pay if you don't want electric however if you want electric you will have to contact the parks and recreation dept and it's like 25.00 plus it keeps your spot no matter who shows up. I had a party there last year and reserved it so I wouldn't have to show up early and two parties had to relocate since I had reserved my spot but I needed electric for the inflatables

They are first come... I dont believe you can reserve in advance

No, you do not have to pay. There are pavilions for parties.