Is this park reachable from Lambs road, Pitman? If you follow the stream south, do you get to Alcion Lake (again in Pitman). Old stopping grounds for me (if this is the place). We called it "Lost Lakes", but I know also it's called Mantua Park (or it was). It's been a good 10 years since I have ridden there.

Try GCC x-country trails or Parvin State Park, both have some interesting areas!