Detroit Lake Reservoir (copy)

This file photo from the summer of 2015 shows slips on dry land at Kane's Marina on Detroit Lake Reservoir during a summer of drought. The Army Corps of Engineers is walking away from plans to drain the reservoir to build a temperature cooling tower to create more conducive conditions for spawning fish. 

The U.S. Army of Corps of Engineers appears to be carefully walking away from plans that would require draining the reservoir at Detroit Lake for an extended period — a stretch of time that the Corps said could have lasted from one to two years.

The Corps is working on building a 300-foot temperature control tower at the lake, part of a project to improve conditions for endangered fish in the North Santiam River. The work is required under the terms of a 2008 legal opinion. The goals are to improve fish passage and temperatures for endangered salmon and steelhead. The temperature control tower would mix water from different levels of the reservoir and send it downstream at a temperature that is more conducive for spawning fish.

Regardless of what you think about the merits of spending an estimated $100 million to $250 million on the project, the Corps still is obliged by federal law and the terms of the legal opinion to move ahead with the effort.

That all raised the question of how best to build the temperature control tower, and the Corps was mulling its alternatives. For a time, Corps officials considered a proposal that would drain the reservoir, and you can understand the appeal of that option: Draining would make for considerably easier construction.

But the prospect of draining the reservoir raised a hue and cry among people who live along the North Santiam River, and for valid reasons. For starters, water from the reservoir helps supply drinking water for some 175,000 people. That includes people who live in places like Salem and Stayton, and you might recall that some of those folks already are a little worried about water from the reservoir in the wake of last summer's algae bloom. 

That's not all: The water from the reservoir helps irrigate 800 farms and farmers certainly don't need another dose of uncertainty going into the heart of growing season.

Not to mention the impact on recreational users, who rely on the reservoir for fishing and floating and other uses. (The Statesman Journal newspaper in Salem has cited a report from the consulting company ECONorthwest that concluded Detroit Lake experiences a 2 percent drop in visitors for every foot it is below full pool. That adds up to a substantial economic hit in a region with a heavy dependence on tourism.)

And that doesn't include the potential impacts elsewhere: In 2015, a year when drought conditions triggered a big decline in the lake's water levels, tourists made a beeline for Linn County sites such as Foster and Green Peter reservoirs, putting pressure on the facilities there. 

So you could almost hear the sigh of relief when the Corps officials reported recently that their preliminary environmental impact statement on the project recommends against draining Detroit Lake. 

The decision means that the Corps is leaning toward a somewhat more challenging approach to build the tower: The new plan proposes to attach the tower to the dam; originally, the tower was to be located away from the dam. The new proposal would require divers and underwater explosives. All of that obviously would add to the price tag for the project — but it also means that the work could proceed without draining the reservoir. And considering that the total economic damage from the draining was estimated to be somewhere around $200 million, you can see how the more complicated project suddenly penciled out a lot better.

This process isn't over yet: After all, it involves an environmental impact statement and a government agency, so we're still well shy of the finish line. The Corps' recommendation now heads into another round of public comment and other planning work must be completed before construction begins, potentially sometime in 2021. But you can be sure that plenty of people will be keeping a careful watch on this project, with an eye toward protecting a vital resource for the region. (mm)

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