Hell's Canyon

Today I learned that Hell's Canyon, in Oregon, is deeper, at 2436meters, than the Grand Canyon (1737meters). I also learned that the Snake river, which runs through hells canyon, is one of the major tributaries of the Columbia river and that it is one of the largest rivers in the US, with only three rivers having a higher hydroelectric potential, one of which is the Columbia, and I forgot what the other two are.