As already recommended, go online or call ahead for resurvations. There is a single-wide trailer near the entrance where the pard managers are. They took the payment and assigned campgrounds. I was there on overnight with a low below freezing and the park was 15%-20% full, including tents and motorhomes. Some of them looked like they'd been there for days.
This is a paid campsite for all overnight camping. You will need to go online to the utah parks site and register or call them. Some sites can reserved the day of. But they get pretty booked on weekends.
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