Board Moves Forward With Skookumchuck Dam Studies; Removal Under Consideration

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Plans: WDFW Director in Support of Either Removing Dam or Installing ‘State-Of-The-Art’ Fish Passage System

The Chehalis Basin Board on Thursday approved funding for studies to see if any modifications — or removal — of the TransAlta-owned Skookumchuck Dam would benefit water storage or streamflow for fish species.

The dam, constructed halfway along the 40-mile long Skookumchuck River, has been used the last 51 years as a water source for the Calgary-based company’s steam plant near Centralia. But questions have been raised about the dam’s future as the company plans to shut down its final coal burner in 2025.

In a Sept. 23 letter to the Chehalis Basin Board, Washington state Department of Fish and Wildlife Director Kelly Susewind said the agency sees the removal of the dam or the installation of a state-of-the-art fish passage system as necessary to the wider basin strategy.

But more research will need to be done to see how to improve the river’s Chinook and steelhead populations, Susewind wrote, adding, “ongoing studies will inform whether dam removal or fish passage is preferable.”

Lori Schmitt, a spokeswoman for TransAlta, said the company doesn’t “have any plans to do anything differently other than what we’re doing right now” with the dam following the 2025 divestment.

As an energy source, the dam produces a mere 1 megawatt of energy that’s sold to Puget Sound Energy. It is not currently equipped to serve as a flood retention facility.

A change in operation or dam ownership might be an option in order to alter the dam, said Nat Kale, aquatic species restoration plan manager with the Office of Chehalis Basin.

“TransAlta owns the dam, and TransAlta is currently responsible for the dam, and they currently anticipate being responsible for the dam in perpetuity,” Kale said. “If the dam were removed, that is a question I don’t think anyone could answer right now. It would presumably be a transfer of ownership, but that would be a question to answer in our next phase of analysis.”

Merri Martz, a senior managing scientist with Anchor QEA, the consulting firm that conducted the first phase of studies, presented Thursday to the Chehalis Basin Board its findings so far on the dam.

The work was started at the behest of the Chehalis Basin Board back in March.

The first-phase of research compiled previous studies on pre-dam habitat, fisheries and dam configuration and operation information from TransAlta. It also analyzed waterflow in and out of the dam on current gauges. Possible fish passage options were also presented.

The study included rough dollar estimates for dam removal or modification. It’s estimated to cost anywhere from $20 million to $50 million for partial or full removal. Increasing the facility’s flood storage capacity could cost anywhere from $22 million to $27 million, though the cost would likely be higher due to mitigation and engineering costs, according to a memo from the Office of the Chehalis Basin.

“Really, the current takeaway from this initial analysis is that fish passage and flood storage are really not compatible,” Martz said. “You’re trying to keep the reservoir as full as possible for fish passage and as empty as possible for flood storage, so they really don’t jive very well.”

The current gauge analysis conducted also didn’t take into account changes in waterflow that could come as a result of climate change. The Skookumchuck River is fully fed by seasonal rainwater, which could be impacted by the increasingly drier summers and wetter winters.

Martz said there is a lack of data on fish habitat capacity upstream from the dam, too.

Before the dam was constructed in 1970, WDFW estimated upstream from the reservoir that about 4 to 5 miles served as possible Chinook spawning habitat, 8 miles of coho spawning and more than 20 miles of spawning habitat for steelhead.

But those estimates were made during a time when fish access along most of the river had been reduced due to three splash dams used to float logs — the last of which was removed in 1969.

Today, the Skookumchuck River provides some of the most healthy and important habitat for Chinook spawning in the Chehalis Basin.

One project that could improve downstream passage for juvenile steelhead would be to re-engineer the dam’s sluice way, which would cost about $500,000. While fish are able to come down from the dam’s reservoir during wetter parts of the year through a fish sluice, they’re unable to travel the opposite direction.

Martz said gaining access to Weyerhaeuser-owned land upstream of the reservoir for aquatic species habitat study is currently a “work in progress.” That work will hopefully be part of future studies to be undertaken this biennium.

Currently, there aren’t enough answers as to which direction the dam should take in order to benefit flood mitigation and fish, especially since TransAlta’s dam already produces steady and cool water that’s kept fish populations healthy.

“The study showed that we need to do more studies,” said Chehalis Basin Board member Edna Fund.

Fund said the project has been very important to the City of Centralia and the Office of Chehalis Basin.

“There’s been so many theories about that dam. Trying to get the reality out there and knowing that TransAlta is in transition, this is very important to me as a member of OCB that we continue in this research,” she said.

The Office of the Chehalis Basin has separately been studying the possibility of building a water retention facility on the Chehalis River near Pe Ell. That dam would only hold back water when flooding appears to be imminent and would otherwise allow for the free flow of the river. 

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