Repeat of 2019 not expected so far
Officials says water levels and flows are ‘within or slightly above normal range’
If you look at a satellite image, it’s nice and brown in these southern areas, which is really good: That’s what we want to see.
This year’s early, orderly snow melt in the southern sections of the Ottawa River watershed means that a repeat of last year’s widespread flooding is not expected — unless the weather takes a nasty turn.
With 35 millimetres of rain in the forecast for Sunday, the Rideau Valley Conservation Authority issued a flood watch Friday, meaning there’s a possibility of flooding along the shores of Christie Lake and Wolfe Lake and in low-lying areas of North Gower along Stevens Creek and Taylor Drain.
But officials do not anticipate a repeat of last year’s extreme flooding given that the snow melt along the southern tributaries of the Ottawa River is about three weeks ahead of where it was last year.
“It has been a good, gradual melt,” said Brian Stratton, manager of engineering services for the Rideau Valley Conservation Authority.
That situation stands in stark contrast to last year, when a heavy snowpack melted late and quickly during a wet April, contributing to a disastrous spring flood.
This year, officials with the Ottawa River Regulation Planning Board are cautiously optimistic. “We’re in good shape in many ways, but it’s early,” Michael Sarich, the board’s senior water resources engineer, said Friday.
The board co-ordinates the management of the 13 major reservoirs in the massive Ottawa River drainage basin — an area larger than England — and provides water level forecasts during the spring freshet.
According to the board, water levels and flows on the Ottawa River are “within or slightly above their normal range” for this time of year.
The snowpack is above average in northern sections of the Ottawa River basin, particularly its eastern areas, when compared to the snowfall average between 1985 and 2015. In some places, the snow is 2.5 metres deep.
But the snowpack has been significantly reduced near the river’s southern tributaries, including the Petawawa, Bonnechere, Mississippi Rideau and South Nation river basins.
“If you look at a satellite image, it’s nice and brown in these southern areas, which is really good: That’s what we want to see,” Sarich said. “We want that local water to get into the river and get out before the northern melt arrives.”
Last year, the southern and northern melts happened on top of another, he said, because of the late, wet spring.
The planning board’s officials forecast says that, “while it is not possible to completely rule out the occurrence of a large spring freshet, the factors that are known at this time — i.e., a decreasing snow pack and early spring start — are positive indicators of a year without excessive flooding along the Ottawa River.”
Higher-than-normal rainfalls contributed to the damaging spring floods in 2017 and 2019, and the planning board cautioned that it could not accurately predict precipitation amounts in the next six weeks.
“However,” it added, “weather specialists are seeing signs of average precipitation in the next two weeks, which would be beneficial to the spring freshet period.”
Last year’s flood was the result of a perfect storm of weather factors. An independent review of the flood said it was caused by a colder-than-average winter and spring, a bigger-than-average snowpack, an insignificant winter thaw, and a rapid snow melt with heavy rainfall.
Dozens of homes along the Ottawa River were flooded in late April and May, with the communities of Mattawa, Pembroke, Constance Bay, Quoyon, Gatineau and Rockland all experiencing significant damage. In Ottawa, a state of emergency was declared and 15,000 volunteers filled 1.5 million sandbags to defend homes against the river.
Many of the affected homeowners had also been flooded in 2017. aduffy@postmedia.com