Monday, July 26, 2010
It’s a crisp March morning, and with recent rains raising the water temperature a few degrees, Bob Edwards and Megan Heinrich have their work cut out for them. Fish activity tends to pick up as water temps increase in the spring, and with winter steelhead running strong this season, the two Oregon Department of Fish and Wildlife employees will be working fish for most of the day. With fishermen lining the banks of the Hood River from just below the Powerdale trap where Edwards and Heinrich work, to the mouth at the Columbia, the two get a sneak peak at what the early risers with rods and reels are hoping to hook into.
Along with the Powerdale diversion dam, the fish trapping and counting facility at the same location will be decommissioned this year, and the removal of both will mean significant changes for the fish of the Hood River and its tributaries.
The in-water work period for the decommissioning project begins July 1, so June will be the final month the facility will be in operation. Since its completion in 1996, the roughly $2 million facility — owned by Bonneville Power Administration and operated by ODFW and the Confederated Tribes of Warms Springs — has acted as a replacement for the dam’s fish ladder and served as an important tool for research and regulation of the Hood River and its tributaries above the dam.
In recent years, fish biologists have concentrated their attention on the river’s steelhead populations, and have utilized the facility for an extensive research project aimed at improving the river’s population of both wild and hatchery steelhead.
“Because Powerdale was so low in the basin, and because it allowed us to collect and monitor nearly 100 percent of fish passing upstream, it provided the perfect conditions for a scientific research project,” said Jason Seals, ODFW assistant district fish biologist.
Seals explained that, since the mid-1990s, ODFW has been collecting genetic samples on all steelhead passing through the facility. Among other things, the agency has used the genetic information for two major projects.
The first is that they were able to create an elaborate family tree which is precise enough for researchers to be able to trace a single fish back to its parents, grandparents and so on.
“The project is significant in that it allowed us to determine how reproductively successful the fish we studied are; specifically in regards to hatchery steelhead spawning in the wild,” Seals said. “What we found is that hatchery steelhead are much less reproductively successful than wild ones. Only two generations removed from the wild, they are about 70 percent less reproductively successful.”
The second major project the facility has been involved with is providing confirmed wild Hood River steelhead and salmon as brood stock to the Parkdale Fish Hatchery. Using a series of holding tanks, workers at the trap have been able to collect fish, take scale and genetic samples and hold them safely while the samples are analyzed. Geneticists analyzing the samples are able to compare it to the database (family tree) created over the years and determine the fish’s origin and family history. A percent of wild, Hood River fish, of the right age, sex, and seasonal run are transported to the Parkdale hatchery, where they are used for breeding.
“In the past, fish were collected for brood stock based on what they looked like,” Seals said. “That caused some problems. For example, winter steelhead were bred with summer steelhead, and we started to see some unusual run timing with those hatchery fish. The intent of the hatchery program is to mimic the same life history characteristics as wild fish, and the ability to determine such specific characteristics of our brood stock helps us do that.”
With the removal of the Powerdale facility, the Parkdale Hatchery will see some new challenges in its operations. “Our mission, and the Tribes’ mission at the hatchery, is to restore salmon and steelhead runs in the basin to harvestable levels,” said Chris Brun, production program coordinator for the Confederated Tribes of Warm Springs, which operates the facility in partnership with ODFW. The hatchery was built nearly the same time as the Powerdale trap, and the two have worked closely to supplement the basin’s steelhead population and reintroduce its chinook salmon population. “With the Powerdale trap coming out, it will present new challenges for fish management, but the dam being removed will greatly improve fish passage.”
Since brood stock for the hatchery will, after June, no longer be collected at Powerdale, ODFW plans to install a series of seasonal fish weirs traps on the East and West forks near Dee. The weirs will trap upstream migrating salmon and steelhead, and ODFW will continue to supply the hatchery with brood stock.
“Our primary concern with the project being removed is brood stock,” Brun said. “From a fish management standpoint, Powerdale was a really good tool. But the dam itself was also an obstacle, and taking it out is certainly going to help fish passage.”
In terms of fish management, one major change the river will see is the ability for hatchery fish to pass freely up the river without regulation. Currently, ODFW restricts hatchery steelhead populations to about a 1-to-1 ratio with wild steelhead. Other than fish collected for brood stock, all wild steelhead and salmon are passed upstream of the dam. Only one hatchery steelhead is let up for every native, however, and the rest are tagged and re-released at the mouth of the Hood River. Brun explained that because the salmon program is still in a reintroductory phase, all wild and hatchery salmon are let upstream.
“There’s certainly more hatchery steelhead that return than wild ones,” Seals said. “We haven’t figured out exactly what we are going to do with the program in the future.” He went on to explain that the plan is to use the seasonal weirs to continue to analyze and collect wild fish for brood stock and remove hatchery fish to keep populations balanced.
Decommissioning Powerdale’s 200-foot-long diversion dam, fish trapping facility, intake structure, power canal, steel flume and sand settling basin is going to be a complex project, but by this time next year up- and downstream bound fish will come across a set of cascading rapids where there was once a massive concrete and steel barrier.
To minimize disruption to the river during the project, a temporary cofferdam will be installed upstream, which will force water to go around the dam that is to be decommissioned. Two temporary channels will be created for the river to flow around the project; one near the current parking and public river access and another where the fish trap is.
“We’re going to salvage as much as we can from the facility,” Seals said. “After that, this place is history.”