Drier weather may hold back muddy waters.

Byline: SCOTT MABEN The Register-Guard

If the mild winter weather persists, it's a good bet the McKenzie River won't turn muddy like it did last spring when federal officials mostly drained Cougar Lake to begin a three-year construction project at the dam.

The U.S. Army Corps of Engineers this year hopes to keep the reservoir at the same level it was lowered to last spring - an elevation of 1,400 feet. That's about 130 feet below the usual minimum level for this time of year.

If late winter and spring rains are light, the agency could keep Cougar from rising at all, avoiding the need to release large volumes of muddy water into the South Fork of the McKenzie at the start of the popular spring fishing season.

"It's pretty much dependent on what Mother Nature gives us," Doug Esch, control room operator at the dam, said Wednesday. "Our intent is to keep the reservoir at this minimum construction pool. If we can keep it there, we should see a great reduction in turbidity."

The reservoir was lowered to give workers access to the inside face of the dam, where they will build a temperature-control tower this year. The project is intended to improve habitat for spring chinook salmon and bull trout, which are listed as threatened under the Endangered Species Act.

In a report to be released at the end of the month, the corps concludes that additional analysis of the drawdown and turbidity problem supports keeping the reservoir level low throughout the three-year project, said George Miller, project manager in the agency's Portland office.

The corps had planned to let Cougar refill each winter to 1,532 feet, then lower it again to 1,400 feet, Miller said. Instead, it will try to keep the flood-control reservoir down year-round.

"If we have something that even approximates a normal water year, we think we'll be in good shape," he said.

The corps was heavily criticized last year for spoiling the clarity of the usually pristine McKenzie during the prime fishing and recreation season. River guides, lodge owners and other businesses complained that the murky water below Cougar Dam drove away most of their customers from April into June.

The turbidity was worse than the corps had estimated as the South Fork flowing into the reservoir scoured tons of silt from the exposed lake bed. The river was practically unfishable, particularly for trout fly fishing but also for salmon and steelhead.

In response to the outcry, the corps stopped drawing down the reservoir 25 feet short of its original target. But many who live or work on the river said the gesture came too late, and they blamed the corps for failing to anticipate how much sediment would be kicked up.

Aaron Helfrich, president of the McKenzie River Guides Association, was one of the more vocal critics of the mess created by the drawdown. He's far less worried about the coming season.

"I think the corps is doing a pretty good job with their plans to keep that water evacuated all this winter," Helfrich said. "They're not going to be cutting though the ooze (in the reservoir) again."

At this point, a lot of rain would need to fall in the next couple of months to trigger another major release of water from Cougar, he said.

"If it hasn't happened yet, I don't think it will going into the spring," he said.

So far this winter, the flow in the main stem of the McKenzie has not been anywhere near high enough to require the corps to hold water in either Cougar or Blue River reservoirs, Esch said.

The corps will begin filling Blue River around the first of February, as usual, but will attempt to match the outflow at Cougar Dam to the natural South Fork streamflow, he said.

Esch said he expects a few storms may raise the level of Cougar somewhat but that the reservoir can be quickly lowered again to 1,400 feet.

Climate experts predict the Northwest will be slightly warmer and drier than normal this winter.

"The weather is the big unknown," Esch said. "That's what will drive us one way or another. If we get hammered with some real strong storms, as that water cuts through the sediment there will be some turbidity. After the storms end, within a week or so the turbidity should disappear."

The river's turbidity has spiked three times in the past two weeks after heavy rains. And that's a good thing, Miller said.

"We'd like to see it rain a little more this winter to help us flush out some of the unstable material in the residual pool area, rather than have it all come down at one time in the spring," he said.

A supplemental environmental analysis of the project will be released as part of the corps' new report later this month. Officials plan to schedule a public meeting for mid-February to explain their plans.

"Our conclusions on impacts haven't changed that much," Miller said.

But the agency also plans to do more monitoring to gauge how much sediment has moved downstream and how much of that has settled in the river. "The data we have to date doesn't really answer that question," he said.

The project contractor this year will pour the concrete tower, which is designed to give the corps greater control over the temperature of water released through the dam.

With the ability to draw water from different levels of the reservoir - warmer water near the surface, cooler water near the bottom - operators hope to come close to the natural river temperatures preferred by threatened populations of salmon and bull trout.

A popular spot for boaters, Cougar Lake is scheduled to remain lowered through 2004 and refill in spring 2005.