‘No silver bullet’ for Green Peter problems

By Sarah Brown
Lebanon Local

Following weeks of complaints and concerns – mostly from our neighbors in Sweet Home – about the muddy Santiam River, the South Santiam Watershed Council hosted an informational Q&A meeting on Nov. 30 at the Senior Center.

Greg Taylor, supervisory fisheries biologist for the USACE Willamette Project, gave an explanation for why Green Peter Reservoir was drawn down last month to the lowest point in its history, then took time to answer questions. Approximately five dozen people showed up to the meeting, a fraction of the estimated 200 to 300 who attended a similar meeting in Sweet Home 10 days prior.

Taylor, who’s worked for the U.S. Army Corps of Engineers for 22 years, was one of two Corps representatives on a panel of six that drew up plans following a 2021 injunction that handed the win to plaintiffs Native Fish Society, Northwest Environmental Defense Center and Wild Earth Guardians.

Taylor explained that his position in the Corps is to help the Corps work through issues at the fisheries.

“Some of these issues are incredibly complex and difficult,” he said. “Almost always, when we work through these things, they result in trade-offs.”


USACE Fisheries Biologist Greg Taylor explains about the structure of Green Peter Dam.

Managing fish in a man-made structure

Concerning salmon, in the fall an estimated 70% spawn above Foster Lake while 30% spawn below Foster, Taylor said. Getting the fish through the dam safely is the hardest thing to do for “a whole variety of reasons.”

Green Peter Dam was completed in 1967, built with a regulating outlet (RO) near the bottom, a penstock and turbine above that, and a spillway near the top.

“When you go to manage a dam, you have to work with what you have,” Taylor said.

Past attempts to pass fish through the dam, he noted, didn’t work.

Taylor explained to the Lebanon Local that the dam was originally built with a trap-and-haul system in the base of the dam to pass adult Chinook salmon up the Santiam rivers. The system primarily didn’t work, he said, because the temperatures were too cold.

A juvenile downstream system was also tested, but it was determined that, although there was good fish survival, there weren’t high numbers of the fish. That system was “mothballed” in 1988.

Prior to the new “deep drawdown” plans, the dam would be drawn down for December and January to a low level – what the Corps terms “minimum conservation pool” – for flood management by passing water through the penstock and RO. The dam would begin to refill in February. In October and November, the drawdown would once again begin to reach the minimum conservation pool by December. The minimum conservation pool, however, did not support the passage of Chinook salmon.

What changed

A 2008 Biological Opinion required the Corps to take 96 actions within 15 years that would help spring Chinook salmon, a species on the Endangered Species Act list. The Corps accomplished 87 of them but, admittedly, did not complete all actions because, Taylor said, some needed more time or more funds.

The three plaintiffs then sued the Corps for failure to complete all actions. The plaintiffs won, which entitled them to a remedy of which they requested would be a set of actions. The ultimate goal, Taylor said, is to pass more fish down the Santiam with a higher survival rate.

A panel consisting of two experts representing the plaintiffs and two from the National Marine Fisheries Service (as well as two Corps staff) worked to develop a plan of those actions. The first set of actions (a first phase, if you will) included a draw down of Green Peter to an elevation of 780 feet (142 feet lower than usual), which is expected to help Chinook pass through the RO. The penstock cannot be used for pass-through because the turbines increase fish mortality. In the spring, the Chinook are to be passed over the spillway.

This first phase is expected to be lifted at the end of Dec. 31, 2024, at which time a new set of actions will be determined.

In response to a question about whether the Corps opposed the judge’s ruling, Taylor simply responded that USACE decided not to appeal the decision.

Photo courtesy of Linn County

Impacts to fish and humans

“When you take an action inside these dams to try to do something beneficial, trying to help a fish, there’s always impacts and there’s benefits,” Taylor said. “Silver bullets don’t exist. If you’re looking for an operation that helps all fish, it doesn’t exist.”

Actions can sometimes even help a species while also harming the species. For example, he said, the adults may benefit from an action, but fry (young fish) may be impacted.

“That is just how these things work.”

In the case of the deep drawdown, the first obvious impact was the death of thousands of Kokanee, which died from barotrauma, or a rapid change in pressure. Another negative impact, one that concerns Taylor, is a change in water temperature.

After spawning in the fall, salmon require a very specific temperature to safely lay their eggs below Foster Dam. After this deep drawdown, the Corps has found the temperature is “super close to impacting those eggs in a very negative way,” Taylor said.

A third, and most obvious impact, is the large amount of sediment now floating downstream. Taylor explained there is 56 years worth of layers of sediment accumulated at Green Peter.

“When we had to draw the river down, the first thing the river did was cut down through that accumulated sediment for miles,” he said.

As the heavier stuff settles down, the finer particles stay suspended in the water. It’s a problem that strains municipal water treatment plants, but it also impacts fish.

“Sediment affects fish. Period,” Taylor said.

Looking back on an experiment conducted about 20 years ago with turbidity levels similar to where they are now, the Corps learned much of how it affects fish.

“We didn’t see mortality, but we saw some impact to them.”

Those include problems with gills and disease, and their ability to feed. According to Taylor, thousands of fish are currently being closely monitored at the hatchery below Foster. When asked if the sediment will ruin spawning beds, Taylor said a similar action at Cougar Reservoir showed that not enough sediment was embedded in the beds to cause much concern.

“I’m a heck of a lot more worried about temperatures,” he said.

Also based on past accounts of similar drawdowns and turbid waters, the Corps expects future drawdowns to continue pulling sediment down the Santiam River, but with less magnitude over time.

A small crowd gathered at the Lebanon Senior Center listens to why Green Peter underwent a deep drawdown.

What’s next

As the action plan moves forward, teams of people studying the impacts of the drawdown will report on the bad effects as well as the good, and will determine whether improvements can be made for future actions. It may be possible, Taylor said, that results could support the Corps’ position to ask the judge to modify the operation.

Despite apparent impacts to the fish, Taylor said so far the survival rate appears to be good based on early indications, yet it is still too early to say for sure.

In 2025, a new set of actions will be discussed and determined.

Meanwhile, the Linn County Commission on Nov. 21 decided to take legal action to try to modify U.S. District Court Judge Marco Hernandez’s order, and the City of Sweet Home is also looking into legal action.

At the Lebanon meeting, Commissioner Roger Nyquist urged residents to contact Oregon’s U.S. Senator Ron Wyden, requesting he make an appropriation to “clean up the mess that’s been created.”

More answers to questions

  • USACE has stated there are no plans to remove the dams.
  • The operation does not impact the potential for flooding. In fact, Taylor said, there’s more space at Green Peter to retain more water during the flood season.
  • Based on past deep drawdowns elsewhere, the Corps would have known to expect impacts to the water’s turbidity levels.