List Explination
- The difficulty varies with different water levels
therefore two values are given for the easiest and hardest it
comes at commonly run flows. Furthermore, "P" stands for
portage.
- The quality of the whitewater on the run. Not
taking into account flat water or portages. Hence, something
like the Middle American would get a good rating.
- Starting with the quality of whitewater, then taking
portages, long flatwater stretches, scenery and convenience into account. Hence the Middle American would get a lower rating.