Work under way to restore Chelan River flow, habitat

CHELAN, Wash. – Ruggedly beautiful, the rocky channel and gorge once guided the free-flowing Chelan River from its origin at the southernmost tip of Lake Chelan along a rolling-and-tumbling course to the Columbia River, four miles and more than 400 feet below.

Biologists say northern pikeminnow, chub and possibly cutthroat trout inhabited the river’s upper reach, the approximately two-mile stretch below where the dam is today.

Osprey would circle for fish. Deer and rabbits would venture down for a drink and to nibble on the hardy wheatgrass and sage that softened the harsh desert climate. Cougars would pad down to capture a meal.

The Lake Chelan Hydro Project, completed in 1927, blocked the river, dried up the gorge for most of the year and destroyed much of the hardscrabble diversity.

But more than eight decades later, this dry and unforgiving ecosystem is about to make a comeback.

The Chelan County PUD is at work on a $13.8 million project to restore a year-round flow to the Chelan River and retool its lowest reach to lure spawning steelhead and chinook salmon to areas where they may never have spawned before.

Plans include a nature trail and picnic area in the river’s upper reach and four yearly whitewater events in the gorge for expert kayakers.

The Chelan Gorge rehab project is the product of years of debate that involved state and federal fish, wildlife and environmental agencies and a host of area community members.

Site work began in June and should be finished by fall 2009.

The completed project will restore Chelan River’s old, year-round flow at a slower rate. The planned flow of 80 cubic feet per second is equivalent to the low-flow average of the Entiat River.

The flow will be increased to 300 to 450 cubic feet per second for kayaking events in the gorge beginning next year.

The river’s lowest reach, near the dam’s powerhouse, will be redesigned into a meandering stream that combines the best attributes – water flows, temperature, vegetation and streambed gravel – to attract spawning steelhead and chinook salmon. These fish already spawn nearby, where the powerhouse tailrace channel merges into the Columbia River, just west of the Chelan Falls Road bridge. The new spawning habitat will cover about 2 acres.

The project will also add a 1.5-mile hiking trail extension to Chelan’s Riverwalk Loop Trail. Picnic areas, viewpoints and informative nature signs will dot the way.

An environmental consulting firm with expertise in stream restoration has worked with PUD biologists to design the new “habitat stream” with carefully placed logjams, boulder groupings, plants, river topography and the gravel that migrating fish prefer.

An in-river barrier system of boulders and concrete will protect the habitat stream work from washing away under riverflows that will routinely reach 2,000 to 6,000 cubic feet per second when the dam is spilling in early summer and fall.

At the planned year-round flow of 80 cubic feet per second, all the water coming out of the gorge will flow into the new habitat stream.

At higher flows, the project’s design will preserve the new stream’s 80 cubic feet per second flow and direct excess flow into another, roughly parallel channel, creating a divided river.

Spawning steelhead and chinook also need faster flows, but they arrive during seasons when the dam isn’t usually spilling from mid-March to mid-May for steelhead and from mid-October to late November for chinook.

To speed up stream flow during these spawning seasons, the PUD will use a pumping system to supplement the 80 cubic feet per second riverflow already coming from the dam.

A new pumping station, across from the powerhouse, will pump water from the powerhouse tailrace through a canal to an outlet just upstream of the habitat channel, increasing the flow to about 320 cubic feet per second.

The work at the top of the project the dam isn’t as complicated.

The Lake Chelan Hydro Project works via a 14- to 12-foot-diameter underground pipeline, called a “penstock,” that transports water from the dam 2.2 miles downhill to the powerhouse near the Columbia River.

The dam’s early engineers built a second pipeline into the dam in case future operators wanted to add a second penstock to feed more turbines at the powerhouse.

Water flows later proved insufficient for powerhouse expansion, Chelan Gorge project manager Bill Christman said.

To reintroduce year-round flow into the Chelan River, workers will build a new pipeline off this existing, 17-foot-diameter tunnel stub. They’ll extend the pipeline some 200 feet downstream from the dam, up and over the existing penstock to an outlet at the riverbed.

The new pipeline will carry cold water from the bottom of the Chelan River to the outlet downstream where it will cascade into the riverbed, year-round.

The cold water temperature is important, Christman said. If the water isn’t cold enough when it begins its downhill journey, the region’s hot, arid summers will overheat the water as it flows, making it too warm to support fish.

Christman said engineers ruled out simply spilling from the dam year-round to establish the constant flow, because in the summertime, surface river temperatures are too warm.

Also, the lake level sometimes dips lower than the dam’s spill gates, making it impossible to guarantee a year-round spill.

Eight decades of yearly, high-volume spill events have added to the problem.

Acting as flash floods, these high flows of 2,000-6,000 cubic feet per second on average, with occasional historic spills of more than 20,000 cubic feet per second, have scoured the riverbanks of vegetation that once helped prevent erosion and possibly provided some shade to cool the water.

The planned flow of 80 cubic feet per second is much lower than the estimated 640 cubic feet per second or higher that likely flowed through the undammed river, biologists say. But it’s a negotiated number a volume of water considered adequate for fish habitat, without overly limiting recreation and hydropower generation, Osborn said.

PUD biologists will study the evolution of their Chelan River rehab efforts for 10 years to gauge their effects. They’ll issue yearly progress reports to federal hydropower authorities.

The Lake Chelan Hydro Project is probably one of the region’s least ecologically disruptive dams.

It doesn’t block the path of migrating fish, because salmon and steelhead were never able to navigate the steep, rocky gorge, many biologists say.

The project produces enough electricity to power some 20,000 homes, and its reservoir is a natural lake.

Studies funded by the PUD say that even before the dam was built, sometimes massive yearly floods scoured the river channel and gorge, washing away much vegetation.

At least two previous dams, built in 1892 and 1893 to raise the lake level for irrigation and steamboat navigation, already interrupted the river’s natural flow. Massive floods damaged both these rustic structures.

At its best, the river’s hot, rocky canyon topped by shrub-steppe habitat is harsh and unforgiving.

Why spend $13.8 million on an experiment to create barely 3 acres of additional spawning habitat that fish might not even use? Will the experiment even work?

“That was hotly debated,” the PUD’s Osborn said of a work group of biologists formed during the early and middle stages of dam relicensing. “Had we not felt it had a high likelihood of success, we never would have supported it for the life of the 50-year license.”

Phil Archibald, U.S. Forest Service fishery biologist, said spawning fish have already been drawn to the Chelan River’s lower reach during times of spill.

“If there were no signs that salmon and steelhead had been present there, then this would be a big experiment,” he said. “But if you get flow and substance over the right substrate (gravel), you’ll get spawning.”

Expense, he said, is relative. “What does one bomb cost in Iraq?” Archibald said. “I believe in fish and fisheries and habitat restoration. Because this is how we’re going to regain salmon habitat in the upper Columbia in bits and pieces.”