If you take the middle passage out of Agnes to Murdoch, use the river left portages.  there are portages both sides - left is used more, and more likely to be cleared.

I took right side once - the landing was more obvious than the one on left, and looked easier so...., and wound up carrying the canoe back across the river to the other side when I got to end of trail (continuing on river right had not been cleared for a few years, it looked like - anyway it was easier to walk across the river than to continue on my side) - at that point, the river left portage was split by a short paddle and I picked up the second half of the trail there.