My wife Bev and I were out collecting, when we found a Penstock leading to a generator station. The penstock is at least 8 ft in Diameter, and from the roar of the water inside, I would guesstimate it was running at 1/2 to 3/4 capacity. The Penstock runs from a glacier fed lake at 2500 ft. of elevation, to a turbine at 80 ft above sea-level. Wouldn't want to be a salmon trying to get back upstream.!!!