The Fraser River could ultimately peak at five, six or even seven metres at the Mission gauge. At this point in the 2012 spring freshet, it’s anybody’s guess.
“Because of the above average snowpack, we’re expecting above average flows,” said city staffer Tara Friesen in a report to Chilliwack city council.
River levels are still expected to peak between the end of May and mid-July, and estimates are for levels to reach between 4.5m and 5.5m by next week.
City staff have been conducting routine freshet preparations and monitoring of water levels and forecasts, said Friesen.
Assuming “normal melt conditions” will prevail this spring, the river is expected to peak at 6 metres at the Mission gauge. The average is about 5.5 metres.
But with temperatures on the rise of late, the river could rise noticeably next week, which isn’t something that “would cause us a problem,” she told council. “Our dike system is designed to protect us up to 8 metres at the Mission gauge.”
Some areas in Chilliwack could see overtopping of banks at 6 metres, and sections of the unprotected areas like Carey Point have also seen flooding at 5 metres.
Chilliwack officials are hoping there’s no extreme weather coming for the upper watersheds, particularly the Upper Fraser and the Thompson regions where flows can influence the peaks seen in the lower Fraser.
Construction work on the check dam at Orchard Slough is now complete, said city officials. So is the berm structure built by property owners located between the river and the dike, who were impacted by flooding and seepage last year.
The city has just hired consulting engineers Kerr Wood Leidal to conduct an independent review of flooding or seepage that occurs.
As of May 1, the snowpack in Fraser River watersheds was pegged at 129 per cent of the historical average, according to River Forecast Centre updates.