Typically opens at 7am and closes at dark. 6PM-9PM.
As far as night riding goes...here is the most up to date 411 on the subject.
"Park hours are from dawn til dusk for all users. If an event like a ball game or CX race is happening, park is open until that event ends. If you night ride and there are still events going on, then you "shouldn't" have a problem. If you night ride outside of those parameters you are operating at your own risk and under "DON'T ASK, DON'T TELL."
Your safest bet to not get locked in is to park next door in the church parking lot. If they give you a hard time...leave. Don't give them a hard time because you are a guest in their parking lot.
This goes for North Meck, Beatty, Renni, Fisher Farm and Jetton. Sherman Branch is no beuno on night riding, PERIOD. Gates are closed and locked at dusk. If you park on the rode and night ride, you may very likely get ticketed.
Sorry to be the Debbie Downer but someone's gotta do it.