Lake level looking fine as freshet heats up

May 11, 2023

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Penticton Herald – May 11, 2023

Between now and the end of July, enough water to fill the Toronto Blue Jays’ home stadium nearly 300 times over is expected flow into Okanagan Lake.

Approximately 420 million cubic metres of water is coming, according to estimates prepared by B.C. government staff and used to regulate the level of Okanagan Lake.

Some of the experts who forecast and monitor the numbers appeared Tuesday on a panel hosted by the Okanagan Basin Water Board to set the stage for the 2023 freshet.

And, despite some eye-popping snowpack figures and early hot spell, things aren’t looking too bad.

As of May 1, the snowpack in the Okanagan basin was estimated at 144% of normal, up from 113% just one month earlier.

“Interestingly, a big driver in that has been the fact that it had been cool up until about May 1,” explained Dave Campbell, head of the B.C. River Forecast Centre.

“We’re finding that the snow melt is so rapid right now that even a week on, the May 1 numbers are probably out of date and the amount of melt we’ve seen over the last week has been dramatic.

“So, a lot of that story of a delayed melt is now completely flipped and we’re into rapid snowmelt and real acceleration in terms of the season – so we’re probably two or three weeks ahead of time.”

Campbell said mid-elevation sites in the 1,500-metre range like Brenda Mines and Trout Lake are “essentially out of snow now.”

“And particularly with the weather forecast coming in over the next week (with highs projected to top 30 C) we’re probably going to even transition to near-record snow-free dates through a lot of those upper-elevation sites.”

He cautioned, however, that “with this early melt, that could put pressure later in the season on creeks that rely on that snowmelt component for run-off in the early part of the summer.”

Meanwhile, the forecast water inflow through July into Okanagan Lake is about 104% of normal, according to Shaun Reimer, who manages the water level via operation of a dam in Penticton.

As of Tuesday afternoon, the dam was discharging about 23 cubic metres of water per second into the Okanagan River, with plans to double it to 40 soon.

“That’s very moderate, so we certainly have room to either increase or decrease as weather conditions arise,” added Reimer, who serves as regional section head for public safety and protection in the Ministry of Forests.

Based on the forecasts, he’s hoping to bring the lake’s level to no higher than 20 centimetres below full pool by the end of July.

As of Tuesday afternoon, the lake’s surface was measured at 341.48 metres above sea level – a full metre below full pool of 342.48.

Full pool is is the maximum desired operating level based on a variety of factors, including protection of property and wildlife habitat.

Okanagan Lake’s highest recorded level in modern times was 343.25 m – 77 centimetres above full pool – which resulted flooding right across the region.