If you're talking about below the spillway, it's not legal to go down there. No trespassing signs are posted all around the perimeter.
I haven't been down there in 5 or 6 years at least, but I think I was legal when I was down there. You could hike down the hill to the water without seeing any signs. They did have signs once down by the water - they were posted all along the Eastern edge of the spillway pond telling you not to go past them...but they were all facing the water itself, saying don't go past them into the woods.
Using my somewhat dulled logic, if I can read a sign that says don't go past it, and I don't go past it, then I must be legal where I'm at to be able to read the sign in the first place.
Legal or not, I don't really think there are all that many fish in that pond. It seemed pretty barren to me.