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How low can you go?

by Brian Walker
| March 27, 2010 9:00 PM

Lake Coeur d'Alene is at its second-lowest level in 45 years.

The lake's level was 2,122 feet on Friday, almost 4 feet shallower than the average for the day of 2,125.78. The summer lake level is 2,128.

Hugh Imhof of Avista, which operates the Post Falls Dam that adjusts the level of the lake and Spokane River, said the level is due to a combination of low snow meltoff and precipitation and fish agreements on the Washington side.

"We are currently operating the Post Falls Dam at natural flows," Imhof said. "This is in accordance with fish protection agreements that allow for spawning redband trout downstream. They usually lay eggs the first two weeks of April. It's likely we will start to lower the outflow and raise the lake shortly after that.

"We need to keep the fish eggs watered until they hatch (in early June)."

The water supply forecast for the Coeur d'Alene basin from snow melt is 47 percent of normal.

Avista's Patrick Maher said the fish agreement has been in effect since 2004, but this year the lake level is noticeably down due to the low runoff.

The lake level is finally starting to rise naturally, coming up 4 inches in the past week.

Maher said the dam's spillgates are typically completely closed between mid-June to July 4.1

"This year is so dry we may be closed before Memorial Day, but it really depends on precipitation," Maher said.

Maher said Avista points to the 2006 flooding in Bonners Ferry as a reason for not even touching the dam before April 15.

"Pressure was put on the operators of the Libby dam to bring water to summer levels, but after they did that there was a rainstorm and nowhere to put the rain, flooding the city and Kootenai River," he said. "Even on a dry year, something like this is possible."

Maher believes the mild spring weather has caused people to want to recreate on or along the lake or river earlier than normal. Water levels have been a common question to Avista as a result.

Maher expects the lake level to naturally continue to rise in the coming weeks, but the amount hinges on precipitation.

The dam will be operated under Avista's new license for the first time this summer.

To enhance aquatic habitat for fish and the scenery downstream of the dam, the license requires Avista to maintain a minimum discharge of 600 cubic feet per second from the dam from June 7 until the Tuesday following Labor Day each year, and reduce the minimum discharge to 500 cfs if the lake level drops at least 3 inches below 2,128 feet during the summer full-pool period.

The minimum flow requirement was 300 cfs in the past.

Avista officials said the lake level may continue to drop even if the dam is operating at 500 cfs, but under the license, the 500 cfs requirement would take precedent over the lowering lake level if that occurs.

"Everybody was on board with the license requirements and we think we'll be able to manage (the levels)," Imhof said. "We'll do the best we can to keep the lake level stable, but a lot of things are beyond our control."