Randy on 9/16/2016 8:25:12 PM:
They do close and block off the Paw Paw Tunnel. Don't know the exact date but it's before December. However, there is a trail where you can hike/walk your bike up over the Paw Paw Tunnel. That's the same trail the horses take. You mentioned the C&O. The Big Savage Tunnel would only affect you if you were riding the GAP Trail (past Cumberland, MD). As far as water. There aren't many streams and I would not take the water from the Potomac River. It's polluted!