So I went out paddling the Petawawa tonight and took a really close look at Railway. I can tell you that the water is so high that if you swim down the right side from the very top you won't hit any rocks on the way down. Unfortunately, if you swim Railway down the right side from the top you will spend more than half of the swim underwater and that is a very, very, very long way to go underwater. I think tomorrow I'll just stick to the rubber boat with the tourists.
Also, the water isn't very cold, I wore T-shirt under drysuit and was quite comforable in and out of the water.