This is a classic whitewater day trip in the history of the WCA that I'm looking forward to exploring for the first time. It's a very nice pool & drop river where all the rapids are obvious and there are portage trails along them. The rapids range in difficulty and there are some very challenging rapids and chutes, so you can make the trip as easy or hard as you want by choosing which rapids to run vs portage. It's 16 km but a long day as a result of all the scouting and portaging, so expect to spend around 6 hours on the river.
Update 04/28: there is no online gauge for the Mississagua but recent water management updates suggest that the flows will remain high. There will be some unrunnable rapids with many frequent portages, so try to pack efficiently to transition quickly from paddling to portaging, and be prepared to tackle a few longer portages as well.
Post-trip notes: we found the river at a fun medium level - not too pushy or too boney - which allowed the more adventurous members to run most of the rapids except for the ones that are actually waterfalls. Some rapids were definitely a high Class III, maybe even Class IV in difficulty. The Parks Canada site shows that the upstream water level in Mississagua Lake is dropping fast, so I think we were lucky to catch the last of the spring runoff just before they're going close the dam for the summer. An earlier timing, in mid-late April, would be better for having reliable water levels on this river. We ended up spending about 8 hours on the river, taking our time to scout and run rapids and enjoying a luxurious lunch break in the canyon to soak up the beautiful scenery. Still it didn't feel like nearly enough time to do this river justice - I'll probably run it as an overnight trip next time, with many options for beautiful campsites along the way.
