The level of Okanagan Lake has been lowered in anticipation of a high snowpack runoff this year.

(STEVE ARSTAD / iNFOnews.ca)

Dry March weather has resulted in some modest growth of the region’s snowpacks and it's raising flood concerns.

Seasonal flood risk is elevated in many regions, including the North and South Thompson, the River Forecast Centre said in its monthly snow survey and water supply bulletin release.

BC River Forecast Centre hydrologist Jonathan Boyd says this year's high snowpack level in the North and South Thompson is unusual, and a cause for concern for potential flooding in Kamloops.

He says even though the snowpacks dropped slightly relative to last month's numbers, the snowpacks are the second-highest recorded in 45 years, with the highest numbers recorded in 1999. 

"The 1970s had some high snowpack levels as well. In 1972 there was a perfect storm of conditions for flooding. That year, high snowpacks coincided with both the North and South Thompson Rivers peaking at the same time, leading to much higher water levels than seen in any previous years," he says.

In 1999, even though the snowpacks were slightly higher, spring conditions precluded flooding possibilities.

Boyd says weather will continue to be a factor well into June as far as flooding possibilities in Kamloops goes.

The region's snowpacks generally reach their maximum level by mid-April. While significant changes to the current snowpack are not expected, continued cooler weather could delay the snowmelt, leading to increased seasonal flood risks, the River Forecast Centre says.

Despite cooler than normal temperatures, March’s dry weather contributed to modest snowpack accumulation, with most regions remaining at similar or slight less snowpack relative to their March values.

Local snowpack levels as of April 1 are as follows:

• North Thompson 117 per cent of normal
• South Thompson 123 per cent of normal
• Okanagan   116 per cent of normal
• Nicola   92 per cent of normal
• Similkameen  112 per cent of normal

Public safety and protection section head Shaun Reimer says the March data means a possible lessening of water into Okanagan lake, but for now he is more or less maintaining the status quo.

“At 116 per cent snow pack for the Okanagan and how dry it's been over the last little while, it has meant our inflow into Okanagan Lake has been downgraded somewhat,” he says

He says the March to July inflow prediction for the lake has dropped from 155 per cent of normal to 134 per cent with today’s data.

Reimer says he might have to reduce the projected flow rate somewhat to reach the target for full lake level,  but says there are no immediate plans to change discharge rates at the Okanagan Lake dam for at least a few weeks

“The data doesn’t change anything in the short term,” he says.

The lake should reach the lowest level seen in 2018 sometime tomorrow. Reimer says the lake may come down a bit more before it starts rising again.

“With the kind of warmth we are starting to see, and the rain projected next week, it’s likely the lake will flatten out a little bit and start rising, like it just does this time of year. The middle of April is very typical,” he says.

Reimer says low lake levels are noticeable but “these are the measures we take when we see a high snowpack developing. We draw the lake down.”

“May and June are our typical rainiest periods, it just depends how rainy. Right now I’m pleased with how we’ve positioned ourselves,” he says.

He says tributaries could also present a potential problem with some exceptionally high localized snowpacks, however.

"Depending on how those snowpacks come down, and whether there is rain on snow, we could see some pretty high flows in those tributaries," he says.

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