For a nice stretch of class II-IV rapids in the spring, check out this section of the Petit Nation river. Best run at high water levels in the spring up to June, this 10-kilometre stretch of the Petit Nation River features a smattering of rapids between Portage-de-la-Nation and the take-out at the first bridge you come across. This stretch is also good in the Fall, around November, but the water is 1/2 to 1/3 the volume.
Portage de la Nation, where Highway 321 crosses the river. Not sure where to park, look around and find something safe and be sure not to irritate local home and landowners. Some of the best access points around here are private, so perhaps offer to pay a few bucks for the day.
Take out at the bridge on Rang Saint Louis near, Plaisance. Be sure not to go past this bridge, as up next is the Chutes de la Petit Nation – possibly runnable but definitely needs heavy scouting first.