Frank Frigo, manager of environmental management for the City of Calgary says if the Elbow and Bow rivers were horses, they would be rough stock at the Calgary Stampede and not ponies ready for the show ring.
In other words, approach with caution, especially in June when almost anything can happen, Frigo says.
“June is often the very important month in terms of setting the tone for both water supply and flood risk for the remainder of the season.”
And so Calgary went from drought concerns to flood worries in no time flat.
“Things have vastly shifted in the last few weeks, precipitation at many of the gauges we monitor out in the Elbow catchment and the Bow catchment are up to 130 per cent of what would be normal. Whereas just a few months ago we were in the position that precipitation was sitting at about one in 60-year dry conditions.”
Reservoirs controlling the Bow and Elbow Rivers have been releasing water downstream at normal rates. But things can change in a hurry, says John Jagorinec, water treatment manager for the City of Calgary.
“Upstream we only have 10 hours’ notice if we have a really big flow event coming our way. So, we have to preemptively lower the reservoir this time of year, if snowpack allows, and that way it allows us to lower it the rest of the way in case we do see a big flood.”
But that’s only half the battle, Jagorinec says.
“The tricky piece is, it’s a very fine balance. We have to capture the tail end of runoff to fill the reservoir. Otherwise, if we miss that opportunity, it might take until the following spring to recover the reservoir.
“If we preemptively lower the reservoir too quickly and the rains don’t materialize, we run into challenges with recovery.”
The balancing act won’t end until after the snow melt and the June rains are finished for the year.