You might not have noticed it this summer, but Osoyoos Lake was washing ashore just a little higher than normal.
Tuesday evening you can find out why as the International Osoyoos Lake Board of Control holds its annual public meeting at the Sonora Centre.
Spoiler alert: it has something to do with expected drought conditions earlier this year.
Tuesday, the Board will provide an overview of the role of the International Joint Commission (IJC) — including operation of the Zosel Dam in Washington State — and information on water level conditions to date in 2019.
The board is looking for “comments, concerns and questions” from the public — including explaining why Osoyoos Lake hovered around 912.55 feet into September.
At that level, the lake is almost a foot above its historic norm of about 911.60 feet.
Under normal conditions, an IJC Order specifies that Osoyoos Lake levels be maintained between 911 and 912 feet from May 1 to September 15.
The Order also provides for an expanded range of allowable lake levels between 910.5 and 912.5 feet during drought conditions if forecasts for Similkameen River flow volume and either net inflow to Okanagan Lake or Okanagan Lake levels fail to reach specified values.
“For a drought to be declared, there’s a drought criteria for the Similkameen River at Nighthawk in terms of the forecast or actual flow during the freshet period,” explained board member Brian Symonds. “They were well below that number this year, so that criteria was met.”
Forecasted Okanagan Lake criteria, however, did not meet the Order’s drought criteria and therefore the Board did not declare drought conditions in 2019.
“The Similkameen criteria was met and the Okanagan Lake criteria were close but not quite met,” said Mr. Symonds.
However, continuing concerns about meeting increased demands on water supply and maintaining in-stream flows in the Okanogan River downstream of Osoyoos Lake during the summer prompted Washington State to apply for a temporary deviation from the Order.
The IJC granted the request in June so that spring runoff from the Okanagan basin could be stored and released later in the summer to improve late-summer water supply in the Okanogan River.
Osoyoos Lake levels began to rise in June in accordance with the temporary lake levels and remained around (or just above) 912.50 feet through much of the summer.
The lake’s level started to decline in mid-September — to 912.28 feet — but has since increased again to 912.36 feet.
The historic August average is 911.61 feet, falling to 911.41 feet in September.
So what did that extra foot of lake level mean to local farmers, tourism operators and others who rely on water for their livelihood?
“I know there ware some people who were concerned just because it was happening, but the board did respond to those concerns,” said Mr. Symonds, adding the drought level in past years was set at 913 feet.
“That last six inches seemed to cause real concern for some people. By dropping it down to 912 and a half we found that it really reduced the negative impacts on lakefront owners and people around the lake.
“It does affect some of the recreational use of the lake, too,” he added. “For example, if the lake is higher than there’s a little less clearance under the bridge.”
Want to learn more?
The IJC’s public meeting is scheduled for a 6:30 p.m. start.