The regulations are not exactly the same in QC and ON regs, HOWEVER there is a sign on both sides of the river about 6 kms downstream of the dam. Also, June SIXTEENTH is the opening day.
Also, the Temiscaming dam is currently being rebuilt, so a new ramp was built directly across from Thorne (just before you get to the bridge). I live just down the road so msg me if you have any other questions.