Lake filling fast after heat, rain
Okanagan Lake is filling up fast after a week of unseasonably hot weather followed by a rainy long weekend that triggered a flood warning for most of the B.C. Southern Interior.
The lake’s surface was measured at 342.28 metres above sea level as of Tuesday morning last week, up 80 centimetres in just two weeks, according to Environment Canada.
It left the lake just 20 cm below the fullpool mark at which operators try to hold it by adjusting the dam at the south end of the lake in Penticton.
“We’re not in trouble. Everything is OK,” said Shaun Reimer, who’s in charge of the dam’s operation, in a phone interview Tuesday morning.
Reimer had been aiming to reach the high-water mark near the end of June, but now expects it to arrive about three weeks earlier due to rapid melt of the snowpack.
In the Okanagan, the snowpack was measured at 144% of normal on May 1, but had dipped to just 81% as of May 15, according to the B.C. River Forecast centre.
In the Similkameen, the snowpack plunged from 91% of normal to 38%.
“So what we're trying to do is hold the rate of (lake) rise for a soft landing, but we’re a little bit at the mercy of the weather,” said Reimer.
The dam was releasing approximately 35 cubic metres of water per second, up from 10 just two weeks ago.
The dam’s outflow can safely go as high as 60 cubic metres per second, but there are downstream effects on fish habitat and private property to consider and Reimer said other tributaries to the Okanagan River are also swollen, making it a delicate balance to strike this year.
“The one thing I can say with certainty is we are not getting into a 2017 (flood year) or anything like that,” said Reimer, who noted conditions then and in 2018 were vastly different with late-season snow accumulations.