Fish & Game: Priest Lake siphon no pipe dream

PRIEST RIVER — The Priest River has 40 miles of meandering habitat that boasts complexity and clarity, which makes it perfect for trout species.

But for about six to eight weeks every summer, it becomes too warm for trout.

“It’s kind of like you have this great house and it’s comfortable — except for two hours a day somebody sucks all the oxygen out of it and you’re stuck there. It’s not a very good place to be,” said Chip Corsi, director of the Idaho Department of Fish & Game’s Panhandle region.

But Corsi said there may be a way to infuse the river with cooler water from Priest Lake, which make it more habitable to trout and lure in anglers to cast for them.

Fish & Game is studying the concept of siphoning water from the lake and introducing it downstream and preliminary investigation shows it is hardly a pipe dream. Modeling done by Portland State University shows that water from the lake would warm as it moved downstream, but it stay well below the temperature threshold that discourages trout.

The siphon could cool the river to about 54 degrees. The river temperature reaches the mid-70s at the height of the summer.

Moreover, the siphon would not drink Priest Lake’s milkshake.

“It would not affect the level of the lake. We’re talking about a project that would not change the outflow volume from the lake. It would only change where the water is drawn from and change the temperature,” Corsi told the Idaho Lakes Commission on Wednesday.

Preliminary study also suggests that a siphon would not affect the ecology of the lake, although Corsi said a limnologist would need to be consulted to verify that conclusion.

“It’s a scenario where we need to assure ourselves of that if we’re going to press forward with this idea,” said Corsi.

Forty miles of high-quality trout habitat with reasonably good public access would draw in anglers, who would then spend money at local stores, restaurants and hotels. It likely won’t have the pull of the Snake River’s Henrys Fork, which brings in an estimated $27 million in revenue from visiting anglers.

But Corsi said the enhancement could add as little as $1 million and as much as $3 million annually to the local economy, perhaps even bringing up to par with the economic value of the North Fork of the Coeur d’Alene River.

The cost of the project is expected to reach into the millions, but Corsi said it could ultimately pay for itself over time. It could potentially be funded through dam mitigation funding through the Bonneville Power Administration and Avista, although Fish & Game has not yet secured any commitments from those entities.

The design of the system is also up in the air. Corsi estimated a preliminary design would likely cost tens of thousands of dollars.

“I’m really hopeful for this project. It just seems like a winner to me,” said lakes Commissioner Brent Baker.

But Baker questioned whether river depths would be sufficient at lower flows.

Corsi said there are deep pools and plenty of complex structural habitat even when flows slacken. The water is also clean and clear.

“The only C we’re lacking here is cold,” said Corsi.