Call the city parks department. They will be able to give you the best answer and assist with any reservations that might need to be made.
Not enough tables !
Some parks are state, county, city, and federal. You need to call some campgrounds directly to find if 20 + people are okay. It depends on how much room they have already rented out. Yes reservations would be nice. But you may have to do it 6 to 8 months even a year out. For large groups.
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