Ottawa River levels forecasted to rise this week

Ottawa River levels forecasted to rise this week

The Ottawa River Regulation Planning Board is advising residents that the river’s levels will rise this week, with the possibility of flooding in low-lying areas.

In a press release issued on April 14, the board notes that heavy rain in the upper portions of the watershed between April 11 and 13 have caused an increase in the river levels between Mattawa and Montreal.

“While the absence of snow in a large portion of the basin reduces the risk of significant flooding, it is important to remember that spring water levels depend also on the timing and amount of rainfall during the months of April and May,” the statement notes. “Weather conditions that bring heavy rainfall events can only be known a few days in advance.”

The press release also gave an overview of the steps taken to mitigate the effects of the spring thaw.

“In March, reservoirs had begun an early but cautious re-fill as the snowpack was well-below average while maintaining sufficient storage volume in the event of significant spring rainfall,” the statement reads. “With the latest weather event, the principal storage reservoirs in the northern part of the watershed will store a large portion of runoff from this portion of the basin, thereby reducing flows in downstream areas. However, dams located in the central and southern portions of the basin are essentially “run of the river” facilities with no significant storage capacity. These facilities are not able to reduce flows and the levels associated with increased spring runoff.”

During the spring, the ORRPB releases regular updates forecasting the river levels in several different areas.