Lori Campbell, a water quality specialist who worked on a recently completed water quality study for the Deschutes River drainage, stands next to informational boards outlining their findings during an informational session at The Riv in the Dalles Monday.
The Selective Water Withdrawl structure on the Deschutes was the first facility of its kind, combining fish passage, temperature management and power generation. This graphic shows how it is constructed, with water intake at the bottom of the reservoir and near the surface as well.
Lori Campbell, a water quality specialist who worked on a recently completed water quality study for the Deschutes River drainage, stands next to informational boards outlining their findings during an informational session at The Riv in the Dalles Monday.
Mark B. Gibson photo
The Selective Water Withdrawl structure on the Deschutes was the first facility of its kind, combining fish passage, temperature management and power generation. This graphic shows how it is constructed, with water intake at the bottom of the reservoir and near the surface as well.
An intensive three-year water quality study of the Deschutes River drainage—which includes the Deschutes, Crooked and Metolius rivers—has been completed and information on their findings were made available at an open house in The Dalles Monday night at The Riv. The study found that “there are many ways in which the Deschutes is thriving...other aspects of river health, such as nutrient and algae levels, are more concerning.”
Lori Campbell, a water quality specialist who worked on the study, said they were able to get a very good reading of the river. “We had a drought year, a normal year, and a good high-flow year,” she said, which provided a broad scope of data. She said the study generally confirmed what they already knew—that water quality in the drainage had degraded over time.
She did note, however, that data did not show a significant spike or increase in algae-related pollution downriver when the “selective water withdrawal” structure (SWW), designed to better regulate river temperature and allow migratory fish passage through the system, became operational in 2010.
Although comparative measures of algae levels could not be made due to improper sampling in the past, related factors like nitrate levels were charted over time. There has been an increase, she said, but “the trend to algae didn’t begin with the selective water withdrawal, it has been a much longer trend, historically.” The Pelton and related dams were built in 1958.
Many fisherman on the lower river have in recent years expressed concern in regards to algae increasing in the lower Deschutes, believing it to be directly linked to the SWW.
Jim Manion is the general manager for Warm Springs Power, which runs the SWW as a Confederated Tribes of Warm Springs project in partnership with Portland General Electric (PGE). He said the SWW was built to change the way water from the reservoir was withdrawn. Prior to the new system, water was taken from the very bottom of the reservoir, where it is coldest, and discharged into the lower Deschutes.
In order to reintroduce salmon and steelhead above the dam and improve water temperatures in the lower river—a federal requirement in the re-licensing of the facility as a low impact hydroelectric project—the outtake structure was redesigned to allow warmer water from the surface of the reservoir to be mixed with colder water from below.
The surface flow also allows migratory fish to enter the facility, where they are sorted and trucked to the lower river.
According to the water quality report, the structure is working as intended and has “effectively reconnected the Deschutes Basin, which was artificially divided for half a century.”
It works by creating attractant currents in the surface of Lake Billy Chinook, pulling in juvenile fish and enabling their transport downstream. Prior to the SWW’s installation, juvenile fish were unable to find the outlet to the lower river and couldn’t continue their ocean-going migration. Since construction, over 1.2 million juvenile fish have been passed through the system on their way downstream to the ocean.
By mixing water from both the surface and depths of the reservoir, the SWW also reduces the project’s effect on water temperature in the Lower Deschutes. This restored temperature regime helps juvenile salmon emerge from their spawning gravel earlier. For fall Chinook, this allows the juveniles to grow larger before leaving the river, so they have higher survival rates when they enter the ocean—as reflected in the high return rates of adult fall Chinook the Deschutes has enjoyed since the system became operational, according to the report.
Those changes resulted in more water from the Crooked River, which is relatively warm, to pass downstream, and that increased the algae load in the lower Deschutes. “The algae load is going down river now because of fish passage and water mixing at the dam,” Manion explained, although algae growth occurs both in the reservoir and downstream and has increased throughout the system.
In solving one set of problems, another set of challenges became apparent, he said.
Manion said the study—and the committees formed to consider solutions—will help managers find the best route forward.
“We will be looking at different scenarios regarding how we blend water, and changes in upstream water management to reduce the nutrient load,” he explained. “We are taking a collaborative approach. There are a lot of stakeholders on the river, a lot of challenges.”
Megan Hill, who works with environmental services for PGE, said there were a lot of alternatives to consider. “Maybe you need ‘floods’ to flush out the system; maybe upstream water quality and nutrient reduction will be most important. But there’s no silver bullet, no simple solution—it’s really complicated, and it involves cities as well as irrigation and water districts.”
Based on the results of the study, possibilities for next steps include programs that reduce or mitigate nutrient loading, changes to the operation of the SWW, installation of an algae screen and other options.
The way forward will require the support of all those concerned with the river, said Steve Corson, with PGE corporate communications.
“This isn’t something PGE can just do,” he said. “The project co-owners cannot make unilateral decisions for the project—our direction will be determined through collaboration with our stakeholders and consultation with our regulators.”
A first step, already taken, was the establishment of a broad committee, which formed a fish committee to consider alternatives noted in the water quality report.
Manion and Hill will both be working with those committees in advisory roles.
They are working with members of the Deschutes River Conservancy (DRC), a non-profit organization formed to “restore stream flow and improve water quality in the Deschutes Basin,” according to their website. The group was founded in 1996 as a collaborative, multi-stakeholder organization.
The fish committee is already looking at the study, said Hill. “We’re looking at the next phase,” she said.
Commented