Be aware that the "big log bridge" across the Mersey is no longer intact so you will need to cross at the "broken log crossing " upstream from there which in my opinion will be very hard to do if the Mersey rises only a little and as I have only heard about the "chock stone crossing" below Fergusson Falls and have no Idea as to how safe it is or the conditions down the North bank of the River I suspect this is a Summer ( with no big rain ) journey now.
Unless you wade /swim the Mersey

corvus