The Ottawa River at Ottawa/Gatineau is now at the highest level in the 53 years of on-line records and the Ottawa River/Lac des Deux Montagnes at Sainte-Anne-de-Bellevue at the west end of Montreal is at the highest level in its 97 years of on-line records. The first is 17 cm above its station's record high and the second is 25 cm above its station's high; both are still rising.

https://wateroffice.ec.gc.ca/google_map/google_map_e.html?search_type=province&province=QC

So, not just the usual runoff from the spring snowmelt and wet April.