Do Some Fish Do Better Without the SWW?
Which way to the lower Deschutes? Salmon and steelhead are still having trouble swimming through the reservoir to find the SWW.
The SWW Continues to Disappoint
Reintroduction of anadromous fish above the Pelton Round Butte Complex on the Deschutes River has been a vexing challenge. Numbers of returning adult sockeye, steelhead and Chinook from the reintroduction effort for release upstream of the dams have been anemic, rarely breaking out of low double-digit territory.
Last week, news arrived of an encouraging sign: returning reintroduction origin steelhead broke into three-digit territory, with more than 300 adults already back, and several months to go in the June to May run year in which steelhead are counted. 300 steelhead may not seem like many, but after 15 years of unsuccessful reintroduction efforts, and more than 50 years since PGE abandoned its fish ladder at the Pelton Round Butte Project, it’s at least a trend in the right direction.
The failure of the fish ladder more than half a century ago effectively extirpated salmonids from most of their historic range in central end eastern Oregon, and relegated any reintroduction effort, including the current one, to a traditional trap and haul program.
The recent uptick raises some questions about how carefully fish managers are keeping track of changes made in recent years in how hatchery steelhead are released. Due to these changes, over 30% of the 100,000 steelhead smolts released annually now go directly into the Deschutes downstream from all three dams. This means smolts don’t have to swim through Lake Billy Chinook to reach the reservoir above Round Butte Dam, and the collection facility at the Selective Water Withdrawal Tower (SWW) in the forebay of the reservoir before being trucked downstream.
If totally bypassing the reservoir and SWW begins to look like success for reintroduction, as suggested by this year’s increased steelhead return, what should be the role of the SWW in the future? If bypassing the SWW increases adult steelhead returns, why operate the SWW at all?
Which Fish are Which?
To begin to answer this query, a quick detour through the early life cycle stage of reintroduction hatchery fish is needed.
Prior to 2020, a juvenile hatchery steelhead from the reintroduction program had three truck rides to look forward to in its life. The first was from the hatchery, where it was shipped to an acclimation site adjacent the stream reach upriver of the dams where the steelhead in question would be released. (Acclimation systems allow juvenile fish to recover from the shock of tanker transport as well as a chance to imprint on the chemical signature of their home stream waters.)
The second, should the fish be lucky enough to survive a swim downstream through Lake Billy Chinook to the collection facility at the SWW, was a ride downstream for release into the Deschutes below the dams. If this steelhead were to survive the ocean phase of its life-cycle and return to the fish trap below the re-regulating dam, it would get a third truck ride above the three-dam complex, where it would be released back into Lake Billy Chinook to attempt to spawn successfully in the middle Deschutes, Crooked or Metolius rivers.
By 2015, fisheries managers at ODFW had taken note of disappointing numbers that told them three rides in a tanker and a swim through a reservoir with confusing currents and novel predators was too much. They did three things: first, they switched from releasing only fry (smaller, younger juvenile fish) to a mix of fry and full-term smolts. Next, over a period of years, they doubled the number of full-term smolts for both steelhead and Chinook from 50,000 to 100,000. Last, and perhaps most significantly, they began trucking over 30% of the smolts from upstream acclimation tanks directly to the free-flowing lower Deschutes, effectively eliminating several sources of potential mortality in Lake Billy Chinook.
It seems quite sensible that eliminating the deadly reservoir swim for outmigrating juveniles would lead to a better percentage of adult returns. It may be that this is what we’re seeing with better adult steelhead returns this year. The trouble is, as hatchery release protocols now stand, we’ll never know.
Successful Reintroduction Needs Good Science
Available records indicate ODFW isn’t differentially marking the portion of fish it grants a free pass around the SWW by trucking them directly to the lower river. To differentiate them from the group of fish that make their way through the reservoir from the acclimation sites to the smolt collection facility at SWW, the reservoir-bypassed fish would need a mark other than the left maxillary clip that all hatchery reintroduction fish receive.
Does bypassing the swim through the reservoir and collection at the SWW yield better smolt to adult survival? The only way to know if a change in hatchery release protocols– in this case, some fish bypassing the reservoir and the SWW– is yielding desired results would be to mark the fish that are being treated differently, and this isn’t happening.
Without this differentiation, the lack of an identifying mark also allows PGE to claim reintroduction success for the SWW, even though smolts trucked from the upriver-most tributaries to downstream of the re-regulating dam did not, and will not, encounter the collection facility at the SWW at any stage of their lives.
Some evidence suggests the SWW and the reservoir are a hindrance rather than a help. In 2023, only 19.9 percent of the nearly 70,000 reintroduction steelhead smolts migrating through the reservoir made it to the collection facility at the SWW. The median travel time for these fish was 42 days. For a rough comparison’s sake, in most years, there are hatchery steelhead that swim from Idaho rivers to Astoria in less time.
Trucking a significant portion of outmigrating smolts to bypass the reservoir and the SWW seems at least a tacit admission that the Tower, as currently configured, isn’t drawing adequate numbers of juvenile fish to the collection facility there. That is unfortunate, because that is the main thing the SWW was designed to do. Trucking smolts around the SWW indicates it’s not doing this job well enough.
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