I put up those signs. I had limited sign material and posts to work with, so pardon the partial confusion until we completely resign and map the place, hopefully this fall.
At the bottom, once you come out of the long downhill, you can either turn left and go uphill, straight and go back to the parking lot, or right and end up back at the sandy climb. The new uphill takes you back to the flat top of the hill. The intent is to go right at the T and end up at the top. At that point, you can chose to do whatever you want. Turning sharp left will take you back down the long downhill to do the uphill again, or do whatever you want. Just please don't ride down the new uphill.
The real plan is to eliminate the T and you will go straight and end up with a less steep climb the rest of the way to the top. A new entrance to the old downhill (the rocky stuff to the left) will be built off of the long downhill trail, eliminating all of the confusion. The old downhill will have a bridge over the cross country loop and end up on a flowing downhill line with natural jumps.
I added several redundant "do not enter" signs at the top, and a one way arrow pointing up the hill at the bottom. I also changed the arrows at the top indicating that you can go either way at the fork to only going right to the downhill. Hopefully this clears things up. If I still find people riding downhill, I have some plans for obstacles that will be annoying to ride down, but easy to ride up. Hopefully I don't have to build them.
Long term, possibly this fall, I want to build a connector from near the bottom of the Sandy Bowl back to the bottom of the new climb. That way, you can ride in a kidney-bean shape in a 2-3 mile loop without having to do the sandy climb, or you can do the sandy climb and skip the new return and uphill. It will be your choice.
More mowing will happen this Thursday-Saturday. I have a few more sections to improve. I think I need to leave one section bad just so people appreciate how much better the cleared stuff looks.