This use to be blocked by some 55gallon drums which is why my friend's and I named the trail next to it the "Plutonium" trail. This one is an old one that really just needs some mountain biking on it to make it a great trail. Just head towards the AM tower and just before you get to the big rocks, hang a right. It'll drop you off towards the bottom of the "Plutonium" trail before the smaller lake.
