Photo: Chad Mathews

Zosel Dam regulates Osoyoos Lake water levels at Oroville.

The Washington State Department of Ecology is slowing the flow of water out of Osoyoos Lake earlier than usual due to concerns of drought.

The department says it will be closing the gates at Zosel Dam in an attempt to bring the lake to its maximum mandated level of 912 feet by early May, rather than the typical June 1 date, "to avoid water shortages and low flows later in the summer."

Below-average snowpacks in all area watersheds are being reported, with the Okanagan at 81 per cent of normal on March 1. The Similkameen snowpack, which flows into the Okanagan River south of Zosel Dam, is at 72 per cent.

The U.S. Drought Portal has most of Okanogan County south of Osoyoos in a stage-one moderate drought.

Penticton dam manager Shaun Reimer told Castanet earlier this week computer modelling is telling him to prepare for drought, although he is allowing Okanagan Lake to drift down somewhat to mitigate for the potential of rain. 

Osoyoos lake levels are regulated by targets agreed upon by the International Joint Commission of the Boundary Waters Act between the United States and Canada.

Despite the drought preparations, the Washington State Department of Ecology wants residents around Osoyoos Lake to be aware that the level of the lake can rise beyond 913 feet, as high as 915 feet, during the spring freshet.

“This phenomenon is driven by snowpack and temperatures, and cannot be controlled by Zosel Dam,” said Al Josephy, with Ecology’s Water Resources Program.

“Although the very high levels are rare, we’re reminding lake residents that it can cause inconvenience and occasional flooding to property owners along the lake and down to the site of the dam itself.”

Osoyoos Lake is now at 910.2 feet, but has been rising steadily since Monday.