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Report: Not Enough Information on Delayed Mortality for Fish, Snake River Dams by Matthew Weaver Capital Press, June 27, 2023

A 2007 report recommended against
continuing to try to measure delayed mortality.

A review of scientific literature finds data is lacking to confirm delayed mortality caused by the lower Snake River dams on fish listed under the Endangered Species Act, according to the Pacific Northwest Waterways Association.

Delayed mortality is the death of fish in estuaries or the ocean because of the stress they experienced passing through the dams.

Agricultural stakeholders want lawmakers to understand that "we don't have enough information to make a decision" about dam breaching, said Heather Stebbings, executive director of the Pacific Northwest Waterways Association.

"If you're going to be making a decision as catastrophic to our region, our farming communities, to our economy, to our climate goals, you really need to have all the information in front of you, and we don't have that yet," Stebbings said.

The National Oceanic and Atmospheric Administration National Marine Fisheries Service, or NOAA Fisheries, monitors dam impacts on fish.

Ritchie Graves, NOAA Columbia Hydropower Branch chief, in May told the Capital Press the agency is looking for better ways to measure delayed mortality, calling it "devilishly hard."

PNWA wanted to understand the available science about delayed mortality, Stebbings said.

"There are a lot of variables that are unknown," she said. "Things like fish size come into play, how long it takes the juvenile salmon to get downstream -- just a range of things that are impacting the survival of salmonids that contribute to the delayed mortality conversation."

The scientific review was prepared by Mount Hood Environmental, a fisheries and aquatic toxicology research company, for the Inland Ports and Navigation Group, a collaboration of ports, businesses and public agencies who support navigation, energy, trade, economic development and salmon recovery.

IPNG is managed by the waterways association, a regional trade group representing more than 150 members. IPNG has been involved in ongoing litigation since 2002, and recent mediation between litigation parties overseen by the White House Council on Environmental Quality and Federal Mediation and Conciliation Service.

What the report says
The scientific review concludes that delayed fish mortality may be occurring as a result of carryover effects from exposure to the Columbia River hydrosystem, but mechanisms of delayed mortality are not well-defined, and the magnitude is unknown.

"It is unclear how removal of the lower Snake River dams would reduce hydrosystem-related delayed mortality because the mortality mechanism may be a function of broad-scale habitat changes caused by operation of the entire FCRPS, not exposure to individual dams," the report states.

The report suggests three primary areas to focus research:

• Altering the estuary arrival time for juvenile fish.

• Examining fish for nonlethal injuries.

• Estuary habitat limitations.

In response to questions about the scientific review, NOAA spokesmen Michael Milstein directed the Capital Press to two reports: the agency's 2022 Rebuilding Interior Columbia Basin Salmon and Steelhead report and a 2007 latent mortality report conducted by the Independent Scientific Advisory Board (ISAB) for the Northwest Power and Conservation Council, Columbia River Basin Indian Tribes and NOAA Fisheries, studying the impacts of all eight dams in the Columbia-Snake River system.

The 2022 report called breaching the dams "the centerpiece action" for restoring salmon populations. Agricultural stakeholders criticized the 2022 report for using significant input from two plaintiffs in the federal lawsuit seeking dam breaching.

The 2007 report recommended against continuing to try to measure delayed or latent mortality.

"Its value relative to a damless reference is not useful," the 2007 report states. Instead, the advisory board said, total mortality of in-river migrants and transported fish is the "critical issue" and "has the considerable advantage of being directly measurable."

The report stated there is "a high degree of uncertainty in any estimates" and that ocean conditions affecting survival "vary greatly."

What environmentalists say
In 2020, a coalition of environmental and fishing groups, led by the Earthjustice law firm, sued over the U.S. Army Corps of Engineers, Bureau of Reclamation and Bonneville Power Administration‘s latest dam operations plan.

Amanda Goodin, Earthjustice senior attorney, called delayed mortality "only one of the ways that dams have contributed to the extinction crisis Snake River salmon now face."

"To say we should continue to delay action because we could know more about this one way that dams kill salmon is an industry tactic to maintain a status quo that leads straight to extinction," Goodin said.

"The best salmon scientists in the world" have concluded "repeatedly" that restoring the lower Snake River through dam removal is essential for protecting wild salmon and steelhead from extinction and restoring healthy, fishable salmon populations, she said.

"This literature review doesn't change that scientific consensus," she said.

Next steps
Federal mediation between the litigants will end Aug. 31.

Stebbings in May said that all stakeholders were not being given the same consideration in the mediation process.

"I don't think that picture has changed very much," she said.

Litigation participants have been "extremely quiet" in recent months, she said.

"I think the U.S. government is working internally to try to figure some stuff out," she said.

Goodin said Earthjustice is optimistic.

"We're in a unique position right now to solve two critical regional problems -- restoring the lower Snake River to bring back salmon and replacing the dams with renewable, clean energy," she said.

Earthjustice is working with its partners and behalf of its clients on both issues, she said.

"We are eagerly awaiting a decision from the Biden administration on a plan to breach the lower Snake River dams as soon as possible and replace the services the dams currently provide -- energy, transportation, irrigation -- with options that support thriving communities," she said. "The federal government must uphold its commitments to Northwest Tribal Nations and act quickly and decisively before Northwest salmon and steelhead are lost forever."

Stebbings wants to see more funding brought into the region to better understand delayed mortality, and also basin-wide recovery efforts, including habitat restoration and predator abatement.

"Doing all of the things we know are actually going to benefit the fish in the interim while we find out some more information on this," she said.