On the edge of civilisation is what this river feels like. Just out of the small hamlet of Saint-Stanislas, the Mistassibi is a paddlers delight. This river feels big, with wide, powerful rapids that are fairly continuous.
the first rapids are short, but a good warm up for what is to come. Mid-way through the run is a long, complex rapid that is about 1 km in length. Many routes are possible. After a flatter section, the largest two rapids, Hawaii, and Black Mass (Messe Noire) are in quick succession. Have a look at them if you haven't run them before. After that, easier water leads to the take out on the outside of a sweeping left bend. In the spring time there is an enormous playwave that forms at Black Mass.
To get to the take out; From Dolbeau-Mistassini, take QC-169S, and turn left onto Rang St Louis. When you get to Saint-Stanislas, go and check the current access situation with Wally and his crew at the excellent Quebec Raft at the Western end of town. The usual access has been along a dirt road at the end of Avenue Hebert.
To get to the put in; From Saint-Stanislas, take Chemin de l'Eden for 5km, then turn right onto Chemin du lac Eden. The put in is on the right once you see the river.