Corps plans deep winter drawdown

SANDPOINT — A deep drawdown is planned for Lake Pend Oreille this winter, the U.S. Army Corps of Engineers announced on Tuesday.

The lake was at 2,061.1 feet above mean sea level at midnight on Sunday and the corps is continuing to draft water from the lake. The corps intends to lower the lake to 2,060 feet by the end of the month, 2,057 feet by Oct. 15 and 2,054 feet by Oct. 31.

“The lake is expected to reach the 2,051-foot level during the first week of November,” the corps said in a news release.

Although the corps intends to draw the lake down by as much as 2 feet by the end of the month, the Pend Oreille Basin Commission is asking the agency to lower it by only 1 foot until the month is out to preserve recreational access.

“We’re in discussions about how we ask for that if that’s a possibility,” Mader said.

For the first time since 1996, kokanee populations in the lake had no influence winter lake level management.

The Idaho Department of Fish & Game recommended neither a 2,055-foot level nor a 2,051-foot level because it does not currently have data to justify either elevation, said Chip Corsi, director of Fish & Game’s Panhandle region.

“It doesn’t mean that we’re done looking at the question, but we’re not in a good position to ask for a higher lake level if the data can’t support it,” said Corsi.

The department has relied on egg-to-fry survival rates when making winter pool recommendations, but the reliability of that metric has fallen into question amid closer scrutiny of data collected by Fish & Game.

Fisheries biologists found that survival rates were inexplicably high during deeper drawdowns, which reduces the amount of shoreline spawning habitat.

A University of Idaho masters thesis into the question of lake level management and kokanee is currently under way, but Corsi said the thesis and rigorous review won’t be done until next year.

Corsi said the department is asking the corps to wrap up the drawdown by Nov. 10, before kokanee begin depositing eggs in shoreline gravels. Corsi said the corps agreed to the request.

Winter drawdowns are typically not favored in Bonner County because they restrict access to the lake during winter, although they can be effective in combating Eurasian milfoil because they expose the aquatic noxious weeds.

“From the commission’s standpoint, that’s the benefit we see,” said Mader.

However, the question of kokanee’s influence on future winter pool management looms large for the commission.

“A question we all need to be asking is what does this mean for future lake levels?” said Mader.

Andy Dux, Fish & Game’s fishery research biologist, is slated to make a presentation to the basin commission on kokanee spawning ecology research when it meets at 10 a.m. on Oct. 22 at Dover City Hall.