With Warming Water What's Better for Juvenile Salmon:
With fast-warming water conditions, federal, state and tribal salmon managers this week protested U.S. Army Corps of Engineers' plans to shift juvenile salmon "transportation" from barges to trucks.
The transportation plan is called for in NOAA Fisheries' Endangered Species Act biological opinion regarding listed fish. At this time of year the collection and transport of juvenile salmon, now mostly subyearling fall chinook, is expected to bring survival benefits by hauling fish through the lower Snake/Columbia River hydrosystem, past predators and increasingly unhealthy water conditions.
The Corps' annual "Fish Passage Plan," which is built on BiOp directives, says to begin as of Aug. 17 loading young salmon on tanker trucks instead of the large barges that are used through the spring and early summer.
The salmon managers in a "systems operations request" filed Thursday with the Corps say that the collection channel and raceways, where fish are held for up to 48 hours before transport, are heating up to the point where it would be better to let the fish proceed downstream in-river through turbines, mechanical bypass or spill.
Signing off on the SOR, which was discussed Thursday during a special meeting of the Technical Management Team, were the National Marine Fisheries Service (NOAA Fisheries), U.S. Fish and Wildlife Service, Oregon Department of Fish and Wildlife, Washington Department of Fish and Wildlife, the Idaho Department of Fish and Game, and the Columbia River Inter-Tribal Fish Commission. The TMT includes representatives of Columbia River basin fish and hydro management entities. The Corps and Bureau of Reclamation operate dams in the Federal Columbia River Power System, which includes hydro projects in the Columbia and lower Snake. The SOR asked for the "delay of the start of truck transport at McNary Dam until further notice. Due to relatively high existing water temperatures in the holding raceways at McNary Dam coupled with a very warm forecast in the Tri-Cities region, conditions would not be favorable to collect, hold for up to 48 hours, and transport by truck until conditions can be re-evaluated."
The recommendation to not implement truck transport at McNary Dam on Aug. 17 is based on the following information, the SOR says:
"The raceways have been toasty," NOAA Fisheries' Paul Wagner said of McNary channels where collected fish are held to await transportation downstream. He said that studies that project survival benefits for transportation in such conditions are outdated. The current operations strategy is based on research that ended in 2002, he said.
Since 2002 "a lot of improvements have been made to make the river a better place to migrate," Wagner said of advancements at McNary and the three dams downstream. McNary is in south-central Washington, not far downstream from the confluence of the Columbia and Snake rivers.
Those improvements include an expansion of summertime spill at McNary to 24 hours per day and a juvenile bypass outfall that was relocated to help reduce predator-caused mortality. Top spill weirs have been installed at John Day to provide safer passage and avian predator dissuasion has been installed there as well. Summertime 24-hour spill is also now in place at John Day.
Likewise improved spill patterns which help provide safer passage are being implemented at The Dalles Dam, where a "spillway wall" has been constructed to guide migrating juvenile more quickly downriver and away from predators. Avian wire arrays are there now too to discourage bird predation. At Bonneville Dam surface bypass is likewise in place now to provide safer downstream passage.
"The signatories to this SOR believe that due relatively high existing water temperatures at McNary Dam (Forebay, Tailwater, Raceways, etc.) coupled with a very warm forecast in the Tri- Cities region, conditions would not be favorable to collect, hold, and transport by truck until conditions can be re-evaluated," the SOR says.
Russ Kiefer, representing the state of Idaho, said that it is the consensus "professional opinion" of salmon managers, that foregoing truck transport would provide a survival benefit -- in terms of increased smolt to adult returns from in-river migrants.
"The salmon managers are collectively in agreement that we are more likely to get more adults" with in-river migrations given the potential stresses from warm-water holding, Kiefer said.
The Corps' Doug Baus told the TMT that the dam operators would not implement the SOR but rather rely on a battle plan described in the FPP.
"We haven't seen any elevated mortality at this time," Baus said of McNary's collection channels and holding raceways. If mortality is observed the FOP directs the Corps to ramp up flows toward the dam's mechanical bypass system, and divert collected fish back into the river.
Available data, mostly from the 2002 study, indicate that SARs are better for transported fish, Baus said.
"At this time we don't see the need to implement the SOR," Baus said.
The Nez Perce Tribe's Dave Statler said that the fish managers would be better advised to follow "a preventative" type of strategy. He said that direct mortalities could be only one sign of problems. Holding fish for 48 hours in warmer water can cause biological stress that results in latent mortality and/or disease.
"Knowing of stressful conditions is just as important to consider as actual mortality," Statler said.
"A fish doesn't have to be dead to be impacted," the Washington Department of Fish and Wildlife's Charlie Morrill said.
He said that a "less than prudent action is the one that has been evidently been chosen by the Corps."
learn more on topics covered in the film
see the video
read the script
learn the songs