This one is obvious if you have seen others like it, but otherwise it's a bit tricky.
It's on public (CNM) property, on the north side of the fence. The area is very busy during school hours. Best to come in evening, after school is out and the parking lot is closed. Walk in from Morris St., or cross the footbridge trom Oso Grande Park. During school hours, watch for muggles!
The area has lots of ground squirrel holes. The cache is not in any of these. It's above ground. No toys, and you will need a tool to remove the log. There should be some around. Good luck!