As of Monday at 5 p.m., at least 189 properties in the Grand Forks area had been issued evacuation orders by the Regional District of Kootenay Boundary (RDKB), as water in the Kettle and Granby rivers raced through the watershed after a weekend of heavy rain and snowmelt.
The Boundary was issued a formal flood warning Monday, as that water began to gather downstream.
At the Grano Creek automated snow monitoring station located high in the watershed, 50 millimetres of rain fell on a sizeable snowpack over the weekend, said RDKB emergency operations centre deputy director Chris Marsh in a Monday afternoon update.
“That’s proven to be a huge challenge for us,” Marsh said. Around 3:45 p.m. Monday, real-time gauges for the Granby River at Grand Forks, as well as for the West Kettle and Kettle rivers at Westbridge showed water volumes lowering. But, Marsh said, there can be an approximate 16-hour delay between the Westbridge gauges and what rushes through Grand Forks.
“Residents are warned that the river levels have exceeded bank-full or will exceed bank-full imminently, and that flooding of areas adjacent to the rivers affected will result,” a June 1 RDKB release reads. According to the RDKB, 20-year return levels in the Kettle River would amount to a high flood risk for low-lying properties in the region.
Evacuation centre established in Grand Forks
With the surge in evacuation orders Monday, the RDKB has set up an evacuation centre at the Jack Goddard Memorial Arena in Grand Forks, where evacuees are asked to check in with staff.
— RDKB Emergency Info (@RDKB_Emergency) June 1, 2020
To prepare for flooding, the RDKB declared a State of Local Emergency on May 29, triggering the release of provincial resources to the region. By Saturday morning, Grand Forks residents could see 40 BC Wildfire crew members unfurling giant lengths of orange Tiger dams – fillable bladders used as emergency flood protection – on the southeast corner of downtown Grand Forks.
Across the Kettle River on 68th Avenue between 1st Street and west towards the Interfor mill, crews built a large earth berm to block the river water there, should it have breached its banks. By Saturday evening, however, the city had altered the berm to allow for alternating one-way traffic along that stretch of 68th Avenue, as river forecasts drew a slightly more promising picture.
Some downtown businesses sandbagged their buildings’ most vulnerable points, while a legion of volunteers heaved sandbags seemingly non-stop at the Grand Forks arena, filling thousands for residents who needed them.
Temperatures across the Boundary were initially projected to be more than 10 degrees above average over the last weekend, accompanied by erratic thunderstorms and heavy rain across the Kettle River watershed. Saturday turned out to be much cooler than expected, possibly slowing some snowmelt in higher regions.
Considering the forecast, the BC River Forecast Centre issued a Flood Watch advisory for the Boundary region Thursday, when river flow forecast graphs for the region showed the west end of the Kettle River system near Westbridge predicted to peak above 2018 levels, when low-lying properties in that region were damaged in a one in 100-year flood event. As of May 31, the BC River Forecast Centre suggested that the western section of the Kettle would peak at five-year return levels – the highest for the year, but well below 2018 returns.
A projection for the Kettle River at Ferry, Wash., indicated Monday morning that the river was at or near its peak for at least a week, but the trend line for the first week of June suggested the water level would be slow to fall far below a minor flooding stage.
— Jensen Edwards (@jensenedw) June 1, 2020