Is it illegal to be on Tempe beach park grounds after the park is closed?

I'm pretty sure it is unlawful to be messing around on the park, but it's probably loosely enforced. And I'd bet the sidewalk by the lake is always available. However, the parking lot does get closed and locked at closing time and you have to call Tempe police to come let you out. I don't imagine they will be happy when they get there either

Nah, I've parked there plenty and cops don't do anything.

I would think so.