Columbia River System Operations and the Future of the Lower Snake River Dams
Congressional research reportJul 31, 2026
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Columbia River System Operations and the
Future of the Lower Snake River Dams
Updated July 31, 2026
Congressional Research Service
https://crsreports.congress.gov
R48089
SUMMARY
Columbia River System Operations and the
Future of the Lower Snake River Dams
Congress has repeatedly debated how to operate and allocate resources from federal water
resources projects—such as multipurpose federal dams—to serve various human needs while
protecting or conserving species listed under the Endangered Species Act (ESA; 16 U.S.C.
§§1531-1544). The Columbia River Basin, which includes the Snake River, is home to numerous
federal and nonfederal dams that provide an array of services within the basin and whose
operations affect certain fish species. Four dams on the Lower Snake River that are owned and
operated by the U.S. Army Corps of Engineers are a focal point for these debates.
The Columbia River Basin supports anadromous salmon and steelhead trout populations, many
of which are now listed as endangered or threatened under the ESA. Four of these listed
populations inhabit the Snake River watershed, a subbasin that encompasses more than 40% of
the larger Columbia River Basin. Federal courts have recognized that certain fish populations in
the Columbia River Basin have economic and religious importance to local Tribes, and the
federal government has acted to establish and protect the treaty fishing rights of Tribes occupying
the Columbia River Basin. Despite federal and nonfederal efforts to protect and recover fish
populations through actions such as altered dam operations and habitat-focused initiatives, listed
salmon and steelhead trout populations remain low in the Columbia River Basin.
R48089
July 31, 2026
Anna E. Normand,
Coordinator
Specialist in Natural
Resources Policy
Pervaze A. Sheikh,
Coordinator
Specialist in Natural
Resources Policy
Erin H. Ward, Coordinator
Coordinator of Research
Planning/ALD
For a copy of the full report,
please call 7-5700 or visit
www.crs.gov.
Due to the potential effects on listed species from operating federally owned Columbia River Basin dams, federal agencies
operating these dams have consulted with the National Marine Fisheries Service under the ESA since the mid-1990s
regarding agency plans for dam operations. Stakeholders have repeatedly sued the federal government over the resulting
biological opinions (BiOps) and decision documents. Much of the litigation has centered on whether the federal agencies
have properly justified their operational plans in light of alternative actions that some argue would better protect listed
species. Debate has included whether the federal agencies should evaluate the alternative of breaching one or more of the
four Lower Snake River dams. Consistent with the federal court’s directive in National Wildlife Federation v. National
Marine Fisheries Service (184 F. Supp. 3d 861 (D. Or. 2016)), the federal agencies considered removal of the dams as one
course of action in a 2020 environmental impact statement (EIS). This option was not selected for implementation. Rather, in
a 2020 record of decision (ROD), the agencies selected an alternative approach that retains the dams and increases the flow at
certain times through several of the dams in the system to benefit migrating fish.
In response to the 2020 ROD, the plaintiffs in the ongoing litigation added claims related to the 2020 BiOp, EIS, and ROD.
In February 2024, the court granted certain parties’ request to stay the litigation through 2028 to allow them to implement a
memorandum of understanding (MOU). In the MOU, the federal government agreed to implement commitments in support
of the Columbia Basin Restoration Initiative, a restoration proposal developed by four Tribes and two states, and agreed to
10-year interim operations of the dams to balance fish and energy needs. In June 2025, President Trump directed a
withdrawal from the MOU, after which the court lifted the stay, and the litigation over the 2020 BiOp, EIS, and ROD
resumed in September 2025. In March 2026, the court issued a preliminary injunction directing the federal government on
how to operate the dams while the litigation proceeds (i.e., following an operations plan similar to the 2025 fish operations
plan).
Legislative options regarding federal dam operations in the Columbia River Basin and the lower Snake River include whether
to continue or alter dam operations and whether to remove the lower Snake River dams. Some Members of Congress have
proposed legislative options that would address these issues in recent Congresses. These proposals and other options typically
entail tradeoffs between the benefits that the dams currently provide and the recovery of ESA-listed fish populations, among
other issues. Significant uncertainty remains as to the potential effects and costs of most options under consideration. For
example, estimates of the cost to replace existing benefits provided by the lower Snake River dams have ranged from $10
billion to $31 billion, mostly for electricity generation and grid services. Congress’s preferred course on how to address
Columbia River System operations, including the lower Snake River dams, may also impact the solutions considered for
other similarly situated federal projects and listed species habitats.
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Columbia River System Operations and the Future of the Lower Snake River Dams
Contents
Introduction ..................................................................................................................................... 1
Columbia River System................................................................................................................... 4
Lower Snake River Dams ......................................................................................................... 5
Navigation Supported by the Lower Snake River Dams .................................................... 7
Water Provided by Lower Snake River Dams for Irrigation, Municipal, and
Industrial Use ................................................................................................................... 8
Hydropower from Lower Snake River Dams ..................................................................... 9
Columbia River System Operations ........................................................................................ 10
Snake River Salmon and Steelhead Trout Populations Listed Under the ESA ............................. 12
Population Trends.................................................................................................................... 14
Factors Affecting Snake River Salmon and Steelhead Trout Populations .............................. 18
Dams and Their Operations .............................................................................................. 19
Habitat Loss and Alteration .............................................................................................. 22
Water Quality .................................................................................................................... 23
Predation ........................................................................................................................... 24
Drought ............................................................................................................................. 25
Climate Change................................................................................................................. 25
Conserving and Restoring Snake River Fishes ....................................................................... 26
Bonneville Power Administration Fish and Habitat Initiatives......................................... 26
NOAA Pacific Salmon Management and Conservation Activities ................................... 28
Columbia River Basin Tribal History and Current Activities ....................................................... 31
Recent Litigation Challenging Agency Actions Related to the Lower Snake River Dams ........... 34
Litigation over FCRPS Biological Opinions and Supplements from 2000 to 2014................ 37
2020 Biological Opinion, Environmental Impact Statement, and Record of Decision ........... 38
Litigation and Administration Actions Following the 2020 Record of Decision .................... 39
2023 Memorandum of Understanding and Litigation Stay .............................................. 40
Trump 2025 Presidential Memorandum and Resumption of Litigation ........................... 44
Congressional Considerations ....................................................................................................... 46
Selected Member Proposals and Legislation .......................................................................... 47
Selected Issues and Questions for Congress ........................................................................... 47
Figures
Figure 1. Columbia River System ................................................................................................... 5
Figure 2. Lower Snake River Dams ................................................................................................ 6
Figure 3. Anadromous Salmon and Steelhead Trout Life Cycle ................................................... 14
Figure 4. Adult Passage of Chinook Salmon Runs at Lower Granite Dam ................................... 16
Figure 5. Systems Used to Improve Juvenile Passage Through Dams.......................................... 22
Figure 6. Federal and Tribal Lands in the Columbia River Basin ................................................. 33
Tables
Table 1. Annual Net Generation from the Lower Snake River Dams, 2015-2025 ........................ 10
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Columbia River System Operations and the Future of the Lower Snake River Dams
Table 2. Snake River Salmon and Steelhead Trout Species Segments and ESA Status ................ 13
Table 3. Identified Past and Recent Snake River Salmon and Steelhead Trout Populations ......... 17
Table 4. Columbia River Basin Fish and Wildlife Program Goals and Objectives ....................... 27
Contacts
Author Information........................................................................................................................ 50
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Columbia River System Operations and the Future of the Lower Snake River Dams
Introduction
Dams serve many purposes, such as generating hydroelectric power, enabling navigation, and
controlling water supply. Dams also can negatively affect ecosystem processes and aquatic
species mobility. For example, dams may impede anadromous fish migrating between the ocean
and upriver spawning areas.1 Congress has repeatedly debated how to allocate resources and
operate federal projects—such as multipurpose federal dams—to serve human needs while also
protecting ecosystems and facilitating the recovery of depleted fish and other species, including
species that are threatened with extinction and listed under the Endangered Species Act (ESA; 16
U.S.C. §§1531-1544).
One area of continued interest to Congress is the Columbia River Basin, which contains
numerous federal and nonfederal dams that provide an array of services within the basin, and
whose operations some consider controversial for their effects on certain fish species.2 The
Columbia River Basin supports Pacific salmon and steelhead trout populations, many of which
are now listed as endangered or threatened under the ESA. Four of these listed populations
inhabit the Snake River watershed, which encompasses over 40% of the larger Columbia River
Basin.3
While the U.S. Army Corps of Engineers (USACE) and the Bureau of Reclamation
(Reclamation) are obligated to operate federal dams that they manage within the Columbia River
Basin to serve the dams’ authorized purposes, they and all federal agencies also have obligations
under the ESA to facilitate the recovery of listed species and ensure that their actions do not
jeopardize the continued existence of such species. They also have obligations under the National
Environmental Policy Act (NEPA; 42 U.S.C. §§4321 et seq.) to consider the effects of their
actions on the human environment. In addition, federal courts have recognized the treaty rights of
some federally recognized Tribes (“Tribes”) to access fish in the Columbia River Basin.4
Accordingly, federal agencies have implemented conservation efforts and considered the effects
of how federal dams in the Columbia River Basin are operated through consultation under the
ESA, environmental review under NEPA, and engagement with stakeholders such as Tribes.
Despite federal and nonfederal efforts to protect and recover salmon and steelhead trout
populations (e.g., modifying dam operations and restoring habitat), several populations remain
1 Fish are anadromous if they spend most of their lives in salt water and then swim up a river to spawn in freshwater.
Young anadromous fish hatch in freshwater and then swim downstream to grow to adulthood in the ocean. For
example, most salmon and some sturgeon species are anadromous.
2 Federal dams are dams owned by the federal government and managed by one or more federal agencies. Federal
dams include dams that were constructed based on congressional authorizations specific to each dam (e.g., most dams
managed by the U.S. Army Corps of Engineers [USACE] and the Bureau of Reclamation [Reclamation]) and dams that
were constructed or acquired through broader authority not specific to an individual dam (e.g., most dams managed by
federal land management agencies). For individually authorized dams, the authorizing statute for each dam provides the
primary guidance for the dam’s management to satisfy authorized purposes; subsequent acts may provide additional
operating authority.
3 National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service (NMFS), Rebuilding
Interior Columbia Basin Salmon and Steelhead, September 30, 2022, pp. 1-42, https://repository.library.noaa.gov/view/
noaa/46461, (hereinafter NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead).
4 A federally recognized Tribe (“Tribe”) is an American Indian or Alaska Native entity that is recognized as having a
government-to-government relationship with the United States, which makes the entity eligible for certain programs
and services. For the 2024 list of Tribes, see Department of the Interior (DOI), Bureau of Indian Affairs (BIA), “Indian
Entities Recognized by and Eligible To Receive Services from the United States Bureau of Indian Affairs,” 89 Federal
Register 99899, December 11, 2024, https://www.federalregister.gov/documents/2024/12/11/2024-29005/indianentities-recognized-by-and-eligible-to-receive-services-from-the-united-states-bureau-of.
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listed under the ESA.5 The low population sizes of listed salmon and steelhead trout in the
Columbia River Basin combined with ongoing stressors such as dams, climate change, and
drought have led to concerns among several stakeholders. Efforts and proposed actions to address
these declines have met resistance from other stakeholders advocating to retain federal dam
operations for the services they provide, such as hydropower, navigation, and irrigation, among
others. These stakeholders have expressed concern that these services may be diminished to
support listed fish species. The debate over which resources and services to prioritize among
stakeholders with different interests in the region has led to various proposals and approaches to
address the issue.
Some stakeholders have pursued their interests through litigation. For example, the decline of
salmon and steelhead trout populations prompted some stakeholders to sue the federal
government under the ESA and other environmental statutes for failing to adequately protect
listed fish in operations plans for dams in the Columbia River Basin. While cases challenging
Columbia River Basin dam operation plans and associated ESA consultation and NEPA review
documents date back to the 1990s—shortly after the first fish populations were listed—the
litigation that has shaped agency actions the last two decades was originally filed by the National
Wildlife Federation (NWF) and other nongovernmental organizations to challenge a 2000
biological opinion (BiOp) on the operations of certain federal dams in the basin.6
NWF’s most recent supplement to its complaint raises claims under the ESA, NEPA, and
Administrative Procedure Act (APA) related to a BiOp, NEPA review, and final agency record of
decision (ROD) issued in 2020.7 In December 2023, the court granted the parties’ request to stay
the litigation for five years while the federal government implemented a memorandum of
understanding (MOU) that outlined commitments in support of a Columbia Basin Restoration
Initiative (CBRI) developed by four Tribes and the states of Washington and Oregon.8 On June
12, 2025, President Trump issued a memorandum directing the heads of federal agencies to take
all appropriate steps to withdraw from the MOU, among other actions.9 On September 11, 2025,
the plaintiffs filed a motion to lift the stay and resume litigation, which the court granted the same
day.10 Accordingly, the litigation over the 2020 BiOp, EIS, and ROD resumed. On March 2, 2026,
the court granted the plaintiffs’ request for a preliminary injunction.11 The preliminary injunction
5 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead.
6 A biological opinion (BiOp) is a written statement from NMFS or the U.S. Fish and Wildlife Service (FWS), or both,
analyzing whether a federal agency’s proposed action is likely to jeopardize the continued existence of listed species or
adversely modify or destroy critical habitat. The BiOp sets forth the agency’s opinion and provides supporting
information for the analysis. 16 U.S.C. §§1536(a)-(b).
7 Bonneville Power Administration (BPA), “Record of Decision; Columbia River System Operations Environmental
Impact System,” 85 Federal Register 63834, October 8, 2020, https://www.govinfo.gov/content/pkg/FR-2020-10-08/
pdf/2020-22147.pdf.
8 Joint Motion to Stay Litigation Through 2028, NWF v. NMFS, No. 3:01-CV-00640 (D. Or. December 14, 2023). The
Tribes that developed the Columbia Basin Restoration Initiative include the Confederated Tribes and Bands of the
Yakama Nation, the Confederated Tribes of the Umatilla Indian Reservation, the Confederated Tribes of the Warm
Springs Reservation, and the Nez Perce Tribe.
9 Executive Office of the President, “Stopping Radical Environmentalism to Generate Power for the Columbia River
Basin,” June 12, 2025, https://www.whitehouse.gov/presidential-actions/2025/06/stopping-radical-environmentalismto-generate-power-for-the-columbia-river-basin/.
10 Joint Motion to Lift Stay, Expedited Consideration Requested, NWF v. NMFS, No. 3:01-CV-00640 (D. Or.
September 11, 2025).
11 Amended Opinion and Order, NWF v. NMFS, No. 3:01-CV-00640, at 40-43 (D. Or. March 2, 2026); Amended
Preliminary Injunction Order, NWF v. NMFS, No. 3:01-CV-00640 (D. Or. March 3, 2026).
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generally retains spill and reservoir levels as set out in the 2025 fish operations plan.12 The
government has appealed the preliminary injunction order to the U.S. Court of Appeals for the
Ninth Circuit.13
In addition to challenging agency actions related to the dams through litigation, some Tribes,
states and environmental groups have proposed plans to recover listed fish populations in the
basin. Some proposals promoted by stakeholders with interests in the listed species and river
ecosystems include actions in support of removing (i.e., breaching) four federally owned dams on
the lower Snake River (collectively referred to as the lower Snake River dams) in the Columbia
River Basin. These dams are owned and operated by USACE for congressionally authorized
purposes of navigation, hydropower, and irrigation, among other benefits. Estimates of the cost of
replacing the benefits currently provided by the lower Snake River dams generally have ranged
from $10 billion to $31 billion, with replacement of electricity generation and grid services
comprising most of these costs.14 Stakeholders with various interests in the services provided by
the dams, as well some Members of Congress and the Trump Administration, have opposed
proposals to remove the dams.15
In light of the repeated litigation and competing stakeholder interests, Congress may consider
legislative options regarding the operations of federal dams in the Columbia River Basin.
Potential legislative options may include dictating specific operational plans and activities related
to the lower Snake River dams, directing how the federal agencies are to prioritize competing
uses, or pursuing dam removal and replacement of benefits. Some Members of Congress have
proposed various legislative options in the recent Congresses related to these strategies. Any
administrative or legislative actions are likely to entail tradeoffs between the benefits that the
dams provide and actions to promote the recovery of ESA-listed fish populations. In addition,
potential actions may inform how federal agencies, stakeholders, and Members consider
approaches to other similarly situated federal projects and listed species habitats.
This report provides background on the lower Snake River dams in the context of federal dam
operations in the Columbia River Basin, ESA-listed Snake River fish populations and associated
recovery initiatives, and recent litigation over operation plans and associated ESA consultation
and NEPA review documents. The report provides selected context for lower Snake River dam
12 Amended Opinion and Order, NWF v. NMFS, No. 3:01-CV-00640, at 40-43 (D. Or. March 2, 2026). Some changes
from the 2025 fish operations plan include more fall and winter spill and full summer spill duration, instead of a
reduced August spill. The court did order flexibility for the federal government to adjust spills and reservoir levels for
emergency power generation and transportation needs. For more information on the 2025 fish operations plan, see
USACE Northwestern Division, Fish Operations Plan Implementation Report, April 2025,
https://public.crohms.org/tmt/documents/FOP_Implementation_Reports/Older/2025_04_FOP-ImplementationReport_Final.pdf.
13 NWF v. Reclamation, No. 26-2139 (9th Cir. April 8, 2026).
14 See Table 2 in the Lower Snake River Dams: Benefit Replacement Report, August 2022, published by the Office of
Governor Jay Inslee of Washington jointly with Sen. Patty Murray. The report was prepared by a consulting team
composed of Seattle-based firm Ross Strategic and DC-based Kramer Consulting. The cost estimate largely reflects the
range of estimates from other groups including BPA and dam breaching advocates. Costs are expressed as the present
value of total costs in 2022 dollars. The methodology for discounting and converting costs from all studies into 2022
dollars is explained in the report. The report excludes some high-end estimates from earlier studies that relied primarily
on new wind and solar energy as replacement resources, because “Senator Murray and Governor Inslee have
determined an energy replacement portfolio only relying on intermittent resources is not a valid path forward.” The
report is at https://governor.wa.gov/sites/default/files/2022-11/
LSRD%20Benefit%20Replacement%20Final%20Report_August%202022.pdf (hereinafter Murray and Inslee, Lower
Snake River Dams).
15 White House, “Fact Sheet: President Donald J. Trump Stops the Green Agenda in the Columbia River Basin,” June
12, 2025, https://www.whitehouse.gov/fact-sheets/2025/06/fact-sheet-president-donald-j-trump-stops-the-greenagenda-in-the-columbia-river-basin/.
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operations with respect to commerce and ecosystem impacts. The report also discusses potential
considerations for Congress, particularly regarding the lower Snake River dams, efforts to recover
ESA-listed Snake River fish populations, recent Administrations’ actions, and litigation
developments.
Columbia River System
Federal dams have affected salmon and steelhead trout populations in the Columbia River Basin
since the 1938 construction of Bonneville Dam, the first dam in the Federal Columbia River
Power System (FCRPS). The FCRPS now includes 31 federal hydropower dams in the Columbia
River Basin operated by either USACE or Reclamation.16 The Bonneville Power Administration
(BPA) markets electric power from these projects.17 USACE, Reclamation, and BPA are generally
referred to in this context as the action agencies. The action agencies consider 14 of the FCRPS
federal dams in the Columbia River Basin to be primary mainstem facilities and refer to these
dams as the Columbia River System (see Figure 1).18 This system includes the four lower Snake
River dams operated by USACE.
16 Reclamation, “Federal Columbia River Power System,” https://www.usbr.gov/pn/fcrps/index.html.
17 In 1937, the Bonneville Project Act (P.L. 75-329; 50 Stat. 731) created the Bonneville Power Project and the BPA to
market and transmit power from federal dams in Pacific Northwest, particularly to public bodies and cooperatives. BPA
is one of four federal power marketing administrations (PMAs). BPA differs from the other three PMAs in that it is
self-financed: it receives no federal appropriations. The Federal Columbia River Transmission System Act of 1974 (16
U.S.C. §838) authorized BPA to cover its operating costs through power rates set to ensure repayment to the Treasury
of capital and interest on funds used to construct the Columbia River power system.
18 Fourteen of the Federal Columbia River Power System (FCRPS) projects are operated as a coordinated system
known as the Columbia River System within the interior Columbia River Basin in the states of Idaho, Montana,
Oregon, and Washington. Projects in the upper Snake, Willamette, and Rogue River Basins are excluded from the
Columbia River System because these projects are coordinated and operated separately. Therefore, the multipurpose
operation of these other FCRPS projects is generally not factored into the coordinated planning scenarios of the
Columbia River System. USACE, Reclamation, and BPA, Columbia River System Operations Environmental Impact
Statement, July 31, 2020, p. 3-374, https://www.nwd.usace.army.mil/CRSO/Final-EIS/ (hereinafter USACE,
Reclamation, and BPA, 2020 EIS).
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Figure 1. Columbia River System
Source: CRS modification of map obtained from U.S. Army Corps of Engineers, Bureau of Reclamation, and
Bonneville Power Administration, “Executive Summary,” in Columbia River System Operations Environmental Impact
Statement, July 31, 2020, p. 6, https://usace.contentdm.oclc.org/utils/getfile/collection/p16021coll7/id/14957.
Notes: This figure depicts the 14 dams of the Federal Columbia River Power System that comprise the
Columbia River System within the interior Columbia River Basin. Other Federal Columbia River Power System
dams and nonfederal dams in the Columbia River Basin are not shown.
Lower Snake River Dams
Some studies have identified the Snake River as being one of the most productive and largest
salmon-producing tributaries of the Columbia River prior to the construction of dams in the
basin.19 Additionally, some tributaries flowing into the Snake River between the lower Snake
River dams and Hells Canyon Dam (e.g., the Salmon River) may provide undammed habitat for
salmon and steelhead trout in areas upstream of the Lower Snake River dams.20
The lower Snake River reach, as defined by the 2020 Environmental Impact Statement (EIS),
extends approximately 178 river miles between Cache Creek (which is upriver from Lewiston,
ID) through the Clearwater River confluence near Lewiston to the Columbia River confluence
downstream near Pasco, WA (see Figure 2).21 Over this reach, USACE constructed four dams
19 Randall F. Schalk, “Estimating Salmon and Steelhead Usage in the Columbia Basin Before 1850: The
Anthropological Perspective,” Northwest Environmental Journal, vol. 2, no. 2 (1986), pp. 1-29; D.J. Nemeth and
Russell B. Kiefer, “Snake River Spring and Summer Chinook Salmon—The Choice for Recovery,” Fisheries, vol. 24,
no. 10 (1999), pp. 16-23 (hereinafter Nemeth and Kiefer, “Snake River Spring and Summer Chinook Salmon,” 1999).
20 While the lower Snake River dams have fish passage facilities, the private hydropower Hells Canyon Dam
approximately 140 miles upstream does not include fish passage facilities. Terry R. Maret and Christopher A. Mebane,
“Historical and Current Perspectives on Fish Assemblages of the Snake River, Idaho and Wyoming,” American
Fisheries Society Symposium, vol. 45 (2005), pp. 41-59.
21 Inflow contributions to the lower Snake River comprise regulated outflows from the upper Snake River Basin and
(continued...)
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that began operation between 1962 and 1975: Ice Harbor, Lower Monumental, Little Goose, and
Lower Granite.22 (See the “Origins of the Lower Snake River Dams” text box below for
information on the authorization and construction of these dams.) The four dams are run-of-river
systems that are equipped with fish passage facilities.23
Figure 2. Lower Snake River Dams
Source: CRS modification of map obtained from U.S. Army Corps of Engineers, Bureau of Reclamation, and
Bonneville Power Administration, Columbia River System Operations Environmental Impact Statement, July 31, 2020,
pp. 3-374, https://www.nwd.usace.army.mil/CRSO/Final-EIS/.
Origins of the Lower Snake River Dams
Congress initially authorized the U.S. Army Corps of Engineers (USACE) in 1902 and 1910 to provide open river
improvements for sections of the lower Snake River. USACE ultimately determined that these methods were not
adequate to ensure a five-foot channel depth between the mouth of the Snake River and Lewiston, ID. The 1925
Rivers and Harbors Act (43 Stat. 1186) directed the Secretary of War, through USACE, and the Federal Power
Commission to estimate the cost of studying the navigable streams and tributaries of the United States for
navigation improvement in combination with the most efficient development of hydropower, flood control, and
irrigation needs. In response, the Secretary of War submitted a report to Congress in 1926 (known as the 308
Report) proposing rivers to study, including the Columbia River and minor tributaries and the Snake River and
tributaries. Congress authorized USACE to conduct some of these studies in the 1927 Rivers and Harbors Act (44
Stat. 1010).
unregulated flows from the Salmon, Grande Ronde, and Imnaha Rivers. Tributary inflows downstream of the Snake
and Clearwater confluence are fairly limited. The Idaho Power Company completed construction of the Hells Canyon
Dam in 1967, which is upstream of the four lower Snake River dams, and blocked fish passage to the upper Snake
River Basin. USACE, Reclamation, and BPA, 2020 EIS, p. C-2-14.
22 USACE, “Lower Snake River Dams,” https://www.nww.usace.army.mil/Missions/Lower-Snake-River-Dams/.
23 A run-of-river system uses a river’s current to generate electricity. In contrast, storage systems use reservoirs to store
water to generate electricity. U.S. Energy Information Administration, “Hydropower Explained,” updated April 20,
2023, https://www.eia.gov/energyexplained/hydropower/.
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USACE transmitted a report to Congress in 1938 following direction from the Rivers and Harbors Act of 1935
(49 Stat. 1028) and a 1938 resolution from the Senate Commerce Committee to further surveys authorized in
1927 while also taking into account economic, scientific, and environmental changes and “relief of unemployment.”
The report recommended general plans for the development of the Columbia and Snake Rivers between the
Bonneville Dam (which began operation in 1938) and Lewiston, ID, for the combined interests of navigation,
irrigation, and hydroelectric power. The report also recommended that Congress authorize and modify portions
of the plan as desired. The Rivers and Harbors Act of 1945 (P.L. 79-14; 59 Stat. 10) authorized USACE to
construct the McNary Dam (on the Columbia River) and authorized “construction of such dams as are necessary,
and open channel improvement for purposes of providing slack water navigation and irrigation” along the lower
Snake River from its confluence with the Columbia River to Lewiston. The act also directed that surplus electric
energy generated at the dams be disposed of in accordance with the Bonneville Project Act (P.L. 75-329; 50 Stat.
731). USACE sited and constructed four dams with lockage facilities: Ice Harbor (began operation in 1962), Lower
Monumental (began operation in 1969), Little Goose (began operation in 1970), and Lower Granite (began
operation in 1975). Completion of the series of dams allowed a barge route from Portland, OR, to the port of
Lewiston, ID, starting in 1975.
Sources: Public laws and reports to Congress from the Secretary of the Army.
Despite operation of fish passage facilities and other conservation measures, investigations have
reported that construction and operation of these dams, in addition to effects from four dams
downstream on the Columbia River, have, in part, resulted in an overall decrease of salmon
returns to the Snake River basin.24 Some scientists have suggested that the lower Snake River
dams are the primary limiting factor for attaining healthy Snake River salmon and steelhead trout
populations listed under the ESA and that restoring some level of pre-dam ecosystem function has
the greatest probability of achieving healthy and harvestable populations of fish.25 Other studies
have identified additional factors affecting salmon and their potential impact on populations (see
“Factors Affecting Snake River Salmon and Steelhead Trout Populations”).
Navigation Supported by the Lower Snake River Dams
Each of the four lower Snake River dams has navigation locks allowing for boat and barge
transportation of people and goods to and from the Pacific Ocean and inland ports.26 USACE
established water elevations behind each dam to maintain an authorized 14-foot channel depth for
the river. The federal government funds operation and maintenance of the locks and navigation
channels on the Snake River. Barge and cruise transportation would not be possible on the Snake
River without the USACE dams and locks.
Wheat is the primary commodity carried on the Snake River; it is transported for export at ship
loading terminals at Portland, OR, and at Vancouver, WA, Kalama, WA, and Longview, WA.27
Snake River shipping contributes about 2.5-3 million tons, or a little more than 20%, of the wheat
24 Nemeth and Kiefer, “Snake River Spring and Summer Chinook Salmon,” 1999; H. A. Schaller et al., “Contrasting
Patterns of Productivity and Survival Rates for Stream-Type Chinook Salmon (Oncorhynchus tshawytscha)
Populations of the Snake and Columbia Rivers,” Canadian Journal of Fisheries and Aquatic Sciences, vol. 56, no. 6
(1999), pp. 1031-1045 (hereinafter Schaller et al., “Contrasting Patterns of Productivity and Survival Rates for StreamType Chinook Salmon,” 1999).
25 Nemeth and Kiefer, “Snake River Spring and Summer Chinook Salmon,” 1999; Schaller et al., “Contrasting Patterns
of Productivity and Survival Rates for Stream-Type Chinook Salmon,” 1999; NMFS, Rebuilding Interior Columbia
Basin Salmon and Steelhead, 2022.
26 Run-of-river dams pass water at the dam at nearly the same rate it enters, but some water backs up behind the dam.
Levels of the water behind these run-of-river dams typically vary from three to five feet in normal operations.
Maintaining water levels within the normal operating range allows the facilities at the dams (e.g., navigation locks,
hydropower turbines, fish ladders, juvenile fish bypass facilities) to function as designed.
27 Washington State, Department of Transportation, Lower Snake River Dams Transportation Study, December 2024,
https://wsdot.wa.gov/sites/default/files/2024-12/Lower-Snake-River-Dams-Transportation-Study-Dec2024.pdf.
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loaded at the deep-draft terminals between Portland and Longview.28 To help contextualize the
Snake River’s wheat tonnage, a commonly sized grain ship loads about 60,000 tons, so the Snake
River in a typical year transports the equivalent of around 42 shiploads of wheat; this represents
about 15% of the nation’s total wheat exports.29 Several barge-loading elevators are dispersed
along the segment of the Snake River that traverses Washington State and in Lewiston, ID.30 In a
typical year, about two-thirds of the wheat shipped on the Snake River originates from the eastern
region of the segment of the river with navigation locks in Washington State.31 The Columbia
River Basin also hosts cruise and riverboat passenger operations. Passengers typically board at
Portland, OR. Some operators sail up the Snake River as far as Clarkston, WA, which is adjacent
to Lewiston, ID.
Water Provided by Lower Snake River Dams for Irrigation, Municipal, and
Industrial Use
Both small- and large-scale nonfederal pumping plants divert slack water behind the four lower
Snake River dams for irrigation at an average of 316,000 acre-feet of water annually.32 These
dams are authorized for irrigation, but no water is stored for irrigation purposes and the projects
do not include specific features to accommodate irrigation or have federal irrigation contracts.33
As of 2022, agriculture production in the Lower Snake River Basin comprises a diverse mix of
tree fruit, herbs, hay, vegetables, cereal grains, pulse crops, and grapes.34 In general, acreage
devoted to cereal grains and pulse crops in this region is not irrigated (e.g., dryland wheat). The
region’s irrigated crops tend to be higher-value annual and perennial crops (e.g., apples, grapes,
onions, and potatoes). The approximately 50,000 average annual irrigated acres are primarily
located near Ice Harbor dam.35
Water users along the Snake River also divert slack water behind the lower Snake River dams for
municipal and industrial (M&I) purposes. The largest surface water withdrawals for M&I
28 USACE, Institute for Water Resources Website, Waterborne Commerce Statistics Center, Waterborne Commerce of
the United States Annual Report, Lock Statistics by River, https://www.iwr.usace.army.mil/about/technicalcenters/wcsc-waterborne-commerce-statistics-center/. Railroads along the entire length of the Snake River’s shoreline
could carry the amount of wheat that is presently barged, but likely at higher cost to the shippers; a transition to rail
also would likely require additional investment to upgrade track and build new facilities. Trucking also could transport
wheat to Columbia River terminals, but the cost of trucking is even higher than the cost of wheat transport by rail.
Trucking wheat may limit the quantity transported due to cost constraints. “Executive Summary” in USACE,
Reclamation, and BPA, 2020 EIS, p. 33.
29 USACE, Institute for Water Resources Website, Waterborne Commerce Statistics Center, Waterborne Commerce of
the United States Annual Report.
30 Upriver from Lewiston, ID, the dams on the Snake River have no navigation locks; thus, there is no barge
transportation service. Lewiston, ID, marks the eastern limit of commercial navigation on the Snake River.
31 USACE, Institute for Water Resources Website, Waterborne Commerce Statistics Center, Waterborne Commerce of
the United States Annual Report, Lock Statistics by River.
32 USACE, Reclamation, and BPA, 2020 EIS, p. 3-1302.
33 USACE, Reclamation, and BPA, 2020 EIS, p. 3-1297.
34 U.S. Department of Agriculture, National Agricultural Statistics Service, Census of Agriculture, “Quick Stats,” 2022,
https://quickstats.nass.usda.gov/.
35 The amount of annual irrigated acres varies by source. The USACE Reclamation, and BPA, 2020 EIS, estimates
48,000 acres of irrigated agricultural production (p. 3-1320). The 2024 Reclamation draft report Lower Snake River
Water Supply Replacement Study estimated average annual irrigation of 55,300 acres from Lower Snake River dam
pools between 2018 and 2023 (p. 3-18). See “Water Provided by Lower Snake River Dams for Irrigation, Municipal,
and Industrial Use” section for more on Reclamation’s 2024 draft report.
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purposes are from slack water behind the Lower Granite dam. M&I users of these water supplies
include the cities of Lewiston, ID, and Clarkston, WA, as well as the Clearwater Paper Mill.36
Hydropower from Lower Snake River Dams
The four lower Snake River dams all have hydropower facilities that generate electricity and
provide additional grid services necessary for electric reliability. Debate about costs and benefits
of the lower Snake River dams frequently encompasses the generation and grid services provided
by the dams, as well as the potential costs of replacing those services if the dams were breached.
Grid services provided by hydropower can be categorized as follows:
•
•
•
•
Capacity. Capacity is a measure of the theoretical maximum potential output of
an electric generator, typically measured in megawatts (MW).37
Annual generation. Annual generation (energy) is a measure of the actual output
of an electric generator over the course of a year, typically measured in
megawatt-hours (MWh).38
Peak generation. Peak generation is a measure of the output of an electric
generator during particular hours of the year when electricity demand is highest.
Ancillary services. Ancillary services is an umbrella term for a number of grid
services that contribute to electric reliability over short timescales, typically
minutes or less.39
Some of these services, such as capacity and annual generation, are easy to quantify, and
information about them is readily available. The capacity and annual generation of the lower
Snake River dams are provided below. Information about other services, such as peak generation
and ancillary services, is less readily available, because formal reporting mechanisms for these
services do not exist. Peak generation and ancillary services are nonetheless important to consider
because they are critical for maintaining electric reliability.
Combined, the lower Snake River dams have a nameplate capacity of more than 3,000 MW. Ice
Harbor has a nameplate capacity of 603 MW,40 and each of the other three dams has a nameplate
36 USACE, Reclamation, and BPA, 2020 EIS, pp. 3-1301–3-1303.
37 Capacity can be reported for an individual electric generator or for the combined output of all generators at a
particular facility (e.g., a dam). Capacity is typically determined by the manufacturer for standard conditions
(nameplate capacity) but also can be reported as a function of typical weather conditions (e.g., winter capacity).
38 Electric generation from hydropower facilities is sometimes reported in terms of average megawatt (aMW). One
aMW is the amount of energy that a power plant with 1 megawatt (MW) capacity would generate if it operated
continuously for a full year. Energy expressed in aMW can be converted to megawatt-hours (MWh) by multiplying by
the number of hours in a year (i.e., 8,760 hours, when not accounting for leap years).
39 For background on ancillary services, see the appendix in CRS Report R45764, Maintaining Electric Reliability with
Wind and Solar Sources: Background and Issues for Congress, by Ashley J. Lawson; and Federal Energy Regulatory
Commission, Reliability Primer, April 23, 2020.
40 In 2016, USACE began replacing the power turbines at Ice Harbor, with the goals of improving fish safety, lowering
maintenance costs, and increasing efficiency. The upgrades are expected to be completed in summer 2026. Walla Walla
District USACE, “USACE Plans Fish Survival Testing This Fall on the Second Improved Fish Passage Turbine,” July
25, 2023, https://www.nww.usace.army.mil/Media/News-Stories/Article/3470373/usace-plans-fish-survival-testingthis-fall-on-the-second-improved-fish-passage/, and Walla Walla District USACE, “New Innovation Earns Ice Harbor
Lock and Dam Recognition,” February 10, 2025, https://www.nww.usace.army.mil/Media/News-Stories/Article/
4061922/new-innovation-earns-ice-harbor-lock-and-dam-recognition/.
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capacity of 810 MW.41 The nameplate capacity of the lower Snake River dams represents about
17% of the total capacity in the FCRPS.42
The lower Snake River dams’ ability to provide generation and ancillary services changes
depending on water levels, operational constraints, conditions within the regional grid, and other
factors. Dry years and seasonal operational constraints for fish protection can limit the dams’
ability to provide these services compared to wet years or when operational constraints are not
limiting. Table 1 shows these dams’ annual generation for 2015-2024 and shows their high yearto-year variability. The annual generation from the lower Snake River dams is reportedly around
one-tenth of BPA’s total system-wide generation.43 As noted above, information about peak
generation and ancillary services from the dams is less readily available. According to the 2020
EIS, the dams provide “more than 2,000 MW of sustained peaking capabilities during the winter,
and a quarter of Bonneville’s [BPA’s] current reserves holding capability.”44
Table 1. Annual Net Generation from the Lower Snake River Dams, 2015-2025
(generation in megawatt-hours [MWh])
Year
Generation (MWh)
2015
6,487,225
2016
7,798,685
2017
10,283,840
2018
9,013,162
2019
8,257,768
2020
6,606,896
2021
5,437,905
2022
6,497,687
2023
6,004,119
2024
5,337,094
2025
6,038,438
Source: U.S. Energy Information Administration, Form 923, July 1, 2026, https://www.eia.gov/electricity/data/
eia923/.
Notes: Net generation is total output from generating facilities minus any electricity consumed on-site. Data for
2025 are subject to change.
Columbia River System Operations
The action agencies’ existing authorities for operating the Columbia River System provide
significant discretion to operate the system for the respective projects’ various authorized
41 BPA, A Northwest Energy Solution: Regional Power Benefits of the Lower Snake River Dams, March 2016, p. 4,
https://www.bpa.gov/-/media/Aep/about/publications/fact-sheets/fs-201603-A-Northwest-energy-solution-Regionalpower-benefits-of-the-lower-Snake-River-dams.pdf.
42 Based on FCRPS capacity of 17,462 MW from all resource types (i.e., hydropower, nuclear, and others).
43 Murray and Inslee, Lower Snake River Dams, p. 66.
44 USACE, Reclamation, and BPA, 2020 EIS, p. 3-944. As described in the 2020 EIS, reserves are spare capacity
within the FCRPS to “increase and sometimes to decrease generation so that electricity generation always equals
demand for electricity.” USACE, Reclamation, and BPA, 2020 EIS, p. 3-822. Reserves are necessary to balance the
grid in real time and maintain reliability.
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purposes,45 subject to legal requirements such as the ESA, NEPA, and the Pacific Northwest
Electric Power Planning and Conservation Act (Northwest Power Act; P.L. 96-501; 16 U.S.C.
§§839a-h).46 These operations are also subject to available funding, which is generally provided
by congressional appropriations or BPA revenues. For example, in a 2022 memorandum, USACE
explained its understanding of the source of its authority and the nature of its discretion as
follows:
[USACE] interprets its project authorities to require that constructed Civil Works projects
be operated and maintained in such a manner that the projects continue to serve their
Congressionally authorized purposes, subject to appropriations and budgeting principles.
Only Congressional action to change the authorization or deauthorize an existing Civil
Works project can alter or terminate this responsibility. However, the manner in which
operation, maintenance, repair, replacement, and rehabilitation is performed is often
discretionary and subject to ESA section 7 consultation.47
For example, USACE has discretion to change the timing and frequency of how it operates a fish
passage facility,48 but USACE does not consider itself as having discretion to breach or
decommission a congressionally authorized dam without action from Congress.49 Discretionary
decisions regarding the Columbia River System operations and maintenance plans, which include
the lower Snake River dams, must comply with the ESA and NEPA.50
45 Congress enacted numerous specific statutes authorizing the construction and operation of each Columbia River
System project, which may differ on the specific purposes for which Reclamation or USACE must operate a project
and may vary in defining how that purpose is implemented at each specific project. Columbia River System projects’
authorizing statutes include hydroelectric power generation, and most also include navigation. All USACE projects are
authorized to support recreation and fish and wildlife conservation per general authorization under the Flood Control
Act of 1944 (P.L. 78-534). The lower Snake River dams also are authorized to provide irrigation as an incidental
benefit, and fish and wildlife mitigation of these projects resulted from negotiations under the Fish and Wildlife
Coordination Act (P.L. 85-624).
46 The Pacific Northwest Electric Power Planning and Conservation Act (P.L. 96-501; 16 U.S.C. §§839a-h) requires
federal agencies, including the action agencies (USACE, Reclamation, and BPA), to exercise their responsibilities for
operating and maintaining Columbia River System projects “to adequately protect, mitigate, and enhance fish and
wildlife … affected by such projects or facilities in a manner that provides equitable treatment for such and fish and
wildlife with the other purposes” of the projects. The act also obligates the action agencies to take into account, at the
relevant stages of their decisionmaking and to the fullest extent practicable, the Columbia River Basin Fish and
Wildlife Program adopted by the Northwest Power and Conservation Council. For information on the program, see
“Bonneville Power Administration Fish and Habitat Initiatives.”
47 USACE and NOAA, “Memorandum Between the Department of the Army (Civil Works) and NOAA,” January 5,
2022, https://www.noaa.gov/sites/default/files/2022-01/
NOAA%20and%20Army%20Civil%20Works%27%20joint%20memorandum%20to%20advance%20Endangered%20
Species%20Act%20Consultations_0.pdf.
48 USACE develops fish passage plans as part of its operation and maintenance strategy to improve fish survival in the
Columbia River System, in accordance with all current and applicable Endangered Species Act (ESA; 16 U.S.C.
§§1531-1544) Section 7 BiOps. Actions in the plan are to be in compliance with all other regulatory requirements (e.g.,
National Environmental Policy Act [NEPA; 42 U.S.C. §§4321 et seq.]) and regional agreements that are in effect at the
time (e.g., fish accords, spill agreements). USACE Columbia River Operational Hydrometeorological Management
System, “Fish Passage Plan (FPP) Homepage,” https://public.crohms.org/tmt/documents/fpp/.
49 For example, the Assistant Secretary of the Army for Civil Works testified at a 2024 hearing that the memorandum
of understanding (MOU) signed by the federal government on December 13, 2023, “recognize[s] that any breaching of
the lower Snake River dams would require specific authorization and appropriations from Congress.” U.S. Congress,
House Committee on Energy and Commerce, Subcommittee on Energy, Climate and Grid Security, Exposing President
Biden’s Plan to Dismantle the Snake River Dams and the Negative Impacts to the United States, 118th Cong., 2nd sess.,
January 30, 2024 (hereinafter Snake River Dam hearing, January 30, 2024).
50 For more information on recent actions related to the ESA and NEPA for the lower Snake River dams, see “Recent
Litigation Challenging Agency Actions Related to the Lower Snake River Dams.”
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The action agencies have issued a series of operations plans for various components of the
FCRPS (e.g., the Columbia River System) or the system as a whole. The action agencies issued
the latest ROD for an operations plan for the Columbia River System on September 28, 2020,
after completing ESA consultation and NEPA review. The 2020 ROD contained the agencies’
plan for operating and maintaining the dams through 2034.51 By agreement, the agencies
subsequently incorporated amended spill operations into the operation plan (see section, “2020
Biological Opinion, Environmental Impact Statement, and Record of Decision”).
Snake River Salmon and Steelhead Trout
Populations Listed Under the ESA
The ESA was enacted to conserve species identified as endangered or threatened and their
habitats.52 Three species of anadromous fishes listed under the ESA are currently found in the
Snake River: Chinook salmon (Oncorhynchus tshawytscha), sockeye salmon (O. nerka), and
steelhead trout (O. mykiss).53 (Coho salmon [O. kisutch] previously occupied the Snake River but
are considered to have been extirpated from the area prior to the 1950s.54)
Anadromous salmonids are often subdivided into specific populations based on spawning run
timing and other biological characteristics (e.g., reproductive isolation from other populations).55
Salmon and steelhead trout populations can be designated as evolutionarily significant units
(ESUs) or distinct population segments (DPSs) for listing under the ESA.56 Under this
classification, four segments (three ESUs and one DPS) of salmon and steelhead trout in the
Snake River are listed as either threatened or endangered under the ESA (Table 2).57 In the entire
Columbia River Basin, 13 salmon and steelhead trout segments are listed as either threatened or
endangered.
51 The consultation in the 2020 Columbia River System BiOp encompasses operations and maintenance of the
Columbia River System for a 15-year period. USACE, Reclamation, and BPA, 2020 EIS.
52 16 U.S.C. §1531. For more detail on the listing of species, agency consultation requirements, and several other ESA
processes, see CRS Report R46677, The Endangered Species Act: Overview and Implementation, by Pervaze A. Sheikh
and Erin H. Ward.
53 These Pacific salmon and steelhead trout species are all classified to the Salmonidae family. The term salmon is used
in this report to include the three listed Snake River salmon and steelhead trout species. This report does not consider
other resident fish species or other salmonids, such as bull trout. FWS, Environmental Conservation Online System
(ECOS), https://ecos.fws.gov/ecp/ (hereinafter FWS, ECOS).
54 Extinction of the stock was acknowledged by NMFS in its 1991 notice for lower Columbia River coho salmon.
NMFS, “Endangered and Threatened Species; Lower Columbia River Coho Salmon,” 56 Federal Register 2955329554, June 27, 1991.
55 The migration of salmon from the sea upstream to spawn is known as a run.
56 The evolutionarily significant unit (ESU) and distinct population segment (DPS) designations are used to identify
meaningful biological units for listings of Pacific salmon and steelhead trout under the ESA. The stock must satisfy two
criteria to be considered an ESU: (1) it must be substantially reproductively isolated from other nonspecific population
units, and (2) it must represent an important component in the evolutionary legacy of the species. The DPS definition
uses the term marked separation rather than reproductive isolation, which is used in the ESU definition. FWS and
NOAA, NMFS, “Policy Regarding the Recognition of Distinct Vertebrate Population Segments Under the Endangered
Species Act,” 61 Federal Register 4722-4725, February 7, 1996; NOAA, NMFS, “Policy on Applying the Definition of
Species Under the Endangered Species Act to Pacific Salmon,” 56 Federal Register 58612-58619, November 20, 1991.
57 Columbia River Basin Federal Caucus, “The Columbia River Basin Federal Caucus,” https://salmonrecovery.gov/;
FWS, ECOS.
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Table 2. Snake River Salmon and Steelhead Trout Species Segments and ESA Status
Species
Segment
Status Under the ESA
Snake River spring/summer run Chinook salmon
(Oncorhynchus tshawytscha)
ESU
Threatened, listed in 1992
Snake River fall-run Chinook salmon (Oncorhynchus
tshawytscha)
ESU
Threatened, listed in 1992
Snake River sockeye salmon (Oncorhynchus nerka)
ESU
Endangered, listed in 1991
Snake River steelhead trout (Oncorhynchus mykiss)
DPS
Threatened, listed in 1997
Sources: U.S. Fish and Wildlife Service, Environmental Conservation Online System (ECOS),
https://ecos.fws.gov/ecp/; National Oceanic and Atmospheric Administration, National Marine Fisheries Service,
“Pacific Coastal Salmon Recovery Fund, Project and Performance Metrics Database: Snake River Coho
Restoration IV,” https://www.webapps.nwfsc.noaa.gov/apex/f?p=309:19:::::P19_PROJECTID:48461776.
Notes: ESA = Endangered Species Act (16 U.S.C. §§1531-1544); DPS = distinct population segment; ESU =
evolutionarily significant unit. Coho salmon (Oncorhynchus kisutch) previously occupied the Snake River but are
considered to have been extirpated from the area prior to the 1950s. The Nez Perce Tribe is actively stocking
the Snake River with coho salmon in an attempt to restore the salmon run.
The National Marine Fisheries Service (NMFS) has designated critical habitat for Snake River
Chinook and sockeye salmon and steelhead trout under the ESA. This habitat includes four types
of areas: (1) spawning and juvenile rearing areas, (2) juvenile migration corridors, (3) areas for
growth and development to adulthood, and (4) adult migration corridors.58
While Pacific salmon and steelhead trout generally have similar life cycles (Figure 3), the Snake
River salmon ESUs and the steelhead trout DPS differ to some degree in their life history
characteristics and habitat requirements. For example, Snake River sockeye salmon spawn in
inland lakeshore gravel and develop in lakes for one to three years before migrating to the
ocean.59 The only remaining Snake River sockeye salmon population returns to Redfish Lake, ID,
approximately 900 miles from the ocean.60 Snake River fall-run Chinook salmon generally spawn
in areas in or near the mainstem of the Snake River, and their juveniles spend less than a year in
freshwater before migrating to the ocean.61 In contrast, Snake River spring/summer-run Chinook
salmon spawn in tributaries, and their juveniles spend more than a year in the freshwater
environment.62 Snake River steelhead trout use many of the same tributaries during their summer
runs as Snake River spring/summer Chinook salmon.63 They generally remain in these areas for
58 For example, NOAA, NMFS, “Designated Critical Habitat: Revision of Critical Habitat for Snake River
Spring/Summer Chinook Salmon,” 64 Federal Register 57399-57403, October 25, 1999. The ESA requires NMFS to
designate critical habitat for any species it lists under the ESA. The ESA defines critical habitat as the areas within the
geographical area occupied by the species at the time it is listed and the areas outside the geographical area occupied by
the species at the time it is listed that are essential for the conservation of the species. 16 U.S.C. §1532.
59 NMFS West Coast Region, ESA Recovery Plan for Snake River Sockeye Salmon (Oncorhynchus nerka), June 8,
2015, pp. 1-431, https://repository.library.noaa.gov/view/noaa/16001 (hereinafter NMFS West Coast Region, ESA
Recovery Plan for Snake River Sockeye Salmon, 2015).
60 NMFS West Coast Region, ESA Recovery Plan for Snake River Sockeye Salmon, 2015, pp. 47-53.
61 NMFS West Coast Region, ESA Recovery Plan for Snake River Spring/Summer Chinook Salmon (Oncorhynchus
tshawytscha) & Snake River Basin Steelhead (Oncorhynchus mykiss), November 2017, pp. 1-282,
https://media.fisheries.noaa.gov/dam-migration/final-snake-river-spring-summer-chinook-salmon-and-snake-riversteelhead-recovery-plan-2017.pdf (hereinafter NMFS, Recovery Plan, 2017).
62 NMFS, Recovery Plan, 2017.
63 NMFS West Coast Region, 2022 5-Year Review: Summary & Evaluation of Snake River Basin Steelhead, July 26,
2022, pp. 1-95, https://repository.library.noaa.gov/view/noaa/45368 (hereinafter NMFS West Coast Region, 2022 5Year Review, 2022).
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less than two years and reach maturity within streams.64 All Pacific salmon species spawn once
before dying at the end of their first breeding season, whereas steelhead trout may spawn more
than once.65
Figure 3. Anadromous Salmon and Steelhead Trout Life Cycle
Sources: National Marine Fisheries Service (NMFS), ESA Recovery Plan for Snake River Spring/Summer Chinook
Salmon (Oncorhynchus tshawytscha) & Snake River Basin Steelhead (Oncorhynchus mykiss), November 2017, p.
64; NMFS, ESA Recovery Plan for Snake River Sockeye Salmon (Oncorhynchus nerka), June 8, 2015, pp. 39, 47;
NMFS, ESA Recovery Plan for Snake River Fall Chinook Salmon (Oncorhynchus tshawytscha), November 2017, p. 30.
Notes: This graphic shows the life cycle for stream-type salmon and steelhead trout: those that mature for a year
or more in freshwater before migrating to the ocean. In addition to growing in tributaries, Snake River sockeye
salmon also rear in Redfish Lake for one to three years before beginning their downstream migrations. There are
also ocean-type salmon, which migrate to the ocean in their first year, largely skipping the “Growing in
Tributaries” step of this diagram. Unlike Pacific salmon species, steelhead trout can spawn more than once. A
redd is a gravel nest.
Some ESUs, such as Snake River spring/summer-run Chinook salmon and Snake River steelhead
trout, consist of different populations that are segregated by specific streams and waterbodies
where they reproduce. Persistence of the ESUs depends on their resilience to threats, such as
habitat alteration, poor water quality, and drought; their genetic diversity,66 and their ability to
adapt to changing conditions.67
Population Trends
Over the last 150 years, many wild Pacific salmon and steelhead trout populations in the Pacific
Northwest have declined; in some cases, their populations are now absent from specific rivers or
64 NMFS West Coast Region, 2022 5-Year Review, 2022.
65 NMFS West Coast Region, Endangered Species Act (ESA) Section 7(a)(2) Biological Opinion and Magnuson-
Stevens Fishery Conservation and Management Act Essential Fish Habitat (EFH) Consultation, WCRO-2020-00624,
July 22, 2020, p. 27, https://repository.library.noaa.gov/view/noaa/29126/noaa_29126_DS1.pdf (hereinafter NMFS,
Biological Opinion, 2020).
66 Shawn R. Narum et al., “Genetic Variation Associated with Adult Migration Timing in Lineages of Steelhead and
Chinook Salmon in the Columbia River,” Evolutionary Applications, vol. 17 (2024), e13626, pp. 1-24.
67 NMFS, Biological Opinion, 2020; Lisa G. Crozier et al., “Climate Vulnerability Assessment for Pacific Salmon and
Steelhead in the California Current Large Marine Ecosystem,” PLoS ONE, vol. 14, no. 7 (2019), article e0217711, pp.
1-49 (hereinafter Crozier et al., “Climate Vulnerability Assessment”). The Crozier et al. study identifies Snake River
sockeye salmon as one of the species most vulnerable to climate change and Snake River spring/summer and fall
Chinook salmon among species that are high in their adaptive capacities to climate change.
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tributaries.68 The current return of wild salmon to the Columbia River Basin is less than 10% of
those values estimated to have been present in the mid-1800s.69 According to scientists, these
declines resulted from many factors, including overfishing, habitat loss, water quality, climate
change, and dam construction, as discussed in the section “Factors Affecting Snake River Salmon
and Steelhead Trout Populations.”70
Experts have estimated that at least 16 million salmon and steelhead trout returned to the
Columbia River Basin annually during the 1800s.71 Although specific previous abundance of
salmon and steelhead trout in the Snake River is uncertain, some experts estimate an abundance
of approximately 2.4 million fishes during that time.72 During the mid-1950s through the 1960s,
an estimated average of 16,000 wild Chinook salmon were harvested annually in Idaho.73 From
1962-1967, the five years following the initial operation of the first lower Snake River dam,
approximately 45,000 adult spring and summer Chinook salmon entered the Snake River basin.74
During the five years immediately following the initial operation of the Lower Granite Dam in
1975, the return of wild spring and summer Chinook salmon declined to approximately 27,000
fish annually, representing “a 40% decrease from 1962-1966 averages.”75
Trends of listed fish populations have fluctuated over various time spans, and illustrate the
interannual variability associated with their abundance estimates. For example, adult passage
counts—estimates of the actual number of passing fish moving upstream at a particular point—
for Snake River Chinook salmon measured at the Lower Granite Dam have fluctuated since
measurements began in 1975 (Figure 4). Adult passage counts are used to estimate abundance
and migration of fish populations, and have fluctuated in roughly 2- to 10-year spans. At times,
values have been two to three times greater than values observed since 2022. These variations
may be the result of natural and human-associated factors.76 For example, peak adult passage
68 NMFS, “Endangered and Threatened Species; Lower Columbia River Coho Salmon,” 56 Federal Register 29553-
29554, June 27, 1991.
69 Columbia Basin Partnership Task Force of the Marine Fisheries Advisory Committee, A Vision for Salmon and
Steelhead: Goals to Restore Thriving Salmon and Steelhead to the Columbia River Basin Phase 1 and Phase 2 Report,
NOAA, 2019 and 2020, https://www.fisheries.noaa.gov/vision-salmon-and-steelhead-goals-restore-thriving-salmonand-steelhead-columbia-river-basin (hereinafter Columbia Basin Partnership Task Force, Phase 1 and 2 Report).
70 Columbia Basin Partnership Task Force, Phase 1 and 2 Report.
71 Randall F. Schalk, “Estimating Salmon and Steelhead Usage in the Columbia Basin Before 1850: The
Anthropological Perspective,” Northwest Environmental Journal, vol. 2, no. 2 (1986), pp. 1-29; Nemeth and Kiefer,
“Snake River Spring and Summer Chinook Salmon,” 1999; and Richard M. Robinson, “Columbia River and Salmon
Passage,” in Restoring America’s Rivers: The Movement for Dam Deconstructions and Rehabilitations (Cham,
Switzerland: Springer Nature, 2025), pp. 167-197.
72 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 8.
73 These harvest estimates were reported for all Chinook salmon cumulatively and independent of seasonal spawning
run. J.F. Keating, The Harvest of Salmon and Steelhead as Determined from Salmon and Steelhead Permits, Annual
completion report. Statewide Fishing Harvest Survey, Federal Aid in Sport Fish Restoration. Project F-18-R-14, Boise,
ID, 1969; J.F. Keating et al., Annual Survey of the Salmon and Steelhead Sport Fishery Harvest in Idaho, Check Station
surveillance of Chinook Salmon Fisheries, Annual completion report. Statewide Fishing Harvest Survey, Federal Aid
in Sport Fish and Wildlife Restoration. Project F-18-R-17, Boise, ID, 1971; Nemeth and Kiefer, “Snake River Spring
and Summer Chinook Salmon,” 1999.
74 Washington Department of Fish and Wildlife (WDFW) and Oregon Department of Fish and Wildlife (ODFW),
Status Report, Columbia River Fish Runs and Fisheries (1938-96), Clackamas, OR, 1997 (hereinafter WDFW and
ODFW, Status Report, Columbia River Fish Runs and Fisheries (1938-96), 1997); Nemeth and Kiefer, “Snake River
Spring and Summer Chinook Salmon,” 1999.
75 WDFW and ODFW, Status Report, Columbia River Fish Runs and Fisheries (1938-96), 1997; Nemeth and Kiefer,
“Snake River Spring and Summer Chinook Salmon,” 1999.
76 See, for example, NMFS West Coast Region, 2022 5-Year Review: Summary & Evaluation of Snake River
Spring/Summer Chinook Salmon, 2022, https://repository.library.noaa.gov/view/noaa/45367.
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counts observed during 2001 included high passage counts during April (i.e., approximately
91,000 adults) and May (i.e., approximately 61,000 adults) in excess of typical values measured
during those months. One study observed greater escapement rates of spring-summer Chinook
salmon during 2001, which the authors concluded may be associated with decreased seasonal
Columbia River discharge, as measured at Bonneville Dam.77 They propose that higher discharge
rates may lead to passage difficulty, increased passage delay, disorientation, or bioenergetic
exhaustion for certain salmon species.
Figure 4. Adult Passage of Chinook Salmon Runs at Lower Granite Dam
(1975-2025)
Source: Columbia Basin Research, “Columbia River DART (Data Access in Real Time),” University of
Washington, School of Aquatic and Fishery Sciences, accessed July 2026, https://www.cbr.washington.edu/dart.
Notes: This figure sums annual adult passage visual counts of Chinook salmon observed during particular times
of the year (i.e., spring Chinook counts from March 1 to June 17, summer Chinook counts from June 18 to
August 17, and fall Chinook counts from August 18 to December 15 of a given year). The passage index is not a
population estimate but is used to adjust collection counts for daily fluctuations in the site’s or project’s
operations. It is considered representative of population trends.
Table 3 provides information about identified past (i.e., since the 1800s) and recent populations
for each of the four Snake River salmon and steelhead trout populations listed under the ESA.
Despite efforts to improve tributary and mainstem habitat and dam passage conditions since the
species were listed under the ESA in the 1990s, most of the populations remain at low abundance
compared to earlier estimates, according to scientists.78 An August 2025 study published by
77 M.L. Keefer et al., “Escapement, Harvest, and Unknown Loss of Radio-Tagged Adult Salmonids in the Columbia
River Snake River Hydrosystem,” Canadian Journal of Fisheries and Aquatic Sciences, vol. 62, no. 4 (2005), pp. 930949.
78 As examples, NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022; NMFS, Snake River FallRun Chinook Salmon Status of the Species, July 2024, pp. 1-6, https://www.fisheries.noaa.gov/s3/2024-08/statusspecies-snake-river-fall-chinook-salmon-jul-2024.pdf; NMFS, Snake River Basin Steelhead Status of the Species
(continued...)
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NMFS scientists observed that multiple ESA-listed salmonid populations had increasing
abundance trends from 1995 to 2020, with those in the Pacific Northwest having higher median
trends than those in California.79 Additionally, the study found that the five-year geometric mean
abundances of fall-run Snake River Chinook salmon and Snake River sockeye salmon (from 2016
to 2020) had increased more than tenfold beyond their mean abundance values from 1995 to
1999.80 The researchers also noted that concurrent stressors related to freshwater and marine
climate negatively affected West Coast salmon populations, and that despite these higher mean
abundance values most salmon populations still remain below their recovery goals.81
Table 3. Identified Past and Recent Snake River Salmon and
Steelhead Trout Populations
Number of
Populations
Identified Since
the 1800s
Number of
Currently
Identified (Extant)
Populations
ESA Listing
Status
Approximate Mean
Abundance from 2010
to 2019 (Calculated as a
Geometrical Mean)
Snake River
spring/summer-run
Chinook salmon ESU
68
28
Threatened
Approximately 7,000
Snake River fall-run
Chinook salmon ESU
2
1
Threatened
Approximately 9,200
Snake River sockeye
salmon ESU
9
1
Endangered
Approximately 46
Snake River
steelhead trout DPS
40
25
Threatened
Approximately 18,700
Snake River coho
salmon ESU
6
2
Extirpated
Approximately 100 being
restocked by the Nez Perce
Tribe
ESU/DPS
Sources: CRS, with data from National Marine Fisheries Service (NMFS), Rebuilding Interior Columbia Basin
Salmon and Steelhead, September 30, 2022; Columbia Basin Partnership Task Force of the Marine Fisheries
Advisory Committee, A Vision for Salmon and Steelhead: Goals to Restore Thriving Salmon and Steelhead to the
Columbia River Basin Phase 1 and Phase 2 Report, National Oceanic and Atmospheric Administration (NOAA),
2019 and 2020; Joint Columbia River Management Staff, Washington Department of Fish and Wildlife and
Oregon Department of Fish and Wildlife, 2023 Joint Staff Report: Stock Status and Fisheries for Fall Chinook
Salmon, Coho Salmon, Chum Salmon, Summer Steelhead, and White Sturgeon, July 10, 2023,
https://www.dfw.state.or.us/fish/oscrp/crm/reports/23_reports/
2023%20OR%20WA%20Fall%20Joint%20Staff%20Report_FINAL_23.07.10.pdf; Joint Columbia River Management
Staff, Washington Department of Fish and Wildlife and Oregon Department of Fish and Wildlife, 2023 Joint Staff
Report: Stock Status and Fisheries for Spring Chinook, Summer Chinook, Sockeye, Steelhead, and Other Species,
February 2, 2023, https://www.dfw.state.or.us/fish/oscrp/crm/reports/23_reports/
2023%20OR_WA%20Spring%20Joint%20Staff%20Report.pdf; W.P. Connor et al., “A Retrospective (circa 18002015) on Abundance, Spatial Distribution, and Management of Snake River Basin Fall Chinook Salmon: Draft 2
Update, July 2024, pp. 1-6, https://www.fisheries.noaa.gov/s3/2024-08/status-species-snake-river-basin-steelhead-july2024.pdf; William J. Lubenau et al., “Encounter Rates and Catch-and-Release Mortality of Steelhead in the Snake
River Basin,” North American Journal of Fisheries Management, vol. 44, no. 1 (2024), pp. 3-20; Joint Columbia River
Management Staff, Stock Status and Fisheries for Spring Chinook, Summer Chinook, Sockeye, Steelhead, and Other
Species, Oregon Department of Fish and Wildlife and Washington Department of Fish and Wildlife, February 4, 2021.
79 Michael J. Ford et al., “Abundance Trends of Pacific Salmon During a Quarter Century of ESA Protection,” Fish and
Fisheries, vol. 26, no. 6 (August 31, 2025), pp. 1087-1106 (hereinafter Ford et al., “Abundance Trends of Pacific
Salmon,” 2025).
80 Ford et al., “Abundance Trends of Pacific Salmon,” 2025.
81 Ford et al., “Abundance Trends of Pacific Salmon,” 2025.
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Parts I, II, and III,” 2016; NMFS, Biological Viability Assessment Update for Pacific Salmon and Steelhead Listed
Under the Endangered Species Act: Pacific Northwest, NOAA Technical Memorandum NMFS-NWFSC-171,
January 2022, https://repository.library.noaa.gov/view/noaa/34363; NMFS West Coast Region, Endangered
Species Act Section 7(a)(2) Biological Opinion and Magnuson-Stevens Fishery Conservation and Management Act
Essential Fish Habitat Response for the Continued Operation and Maintenance of the Columbia River System,
WCRO-2020-00624, July 22, 2020; NMFS, ESA Recovery Plan for Snake River Fall Chinook Salmon (Oncorhynchus
tshawytscha), NOAA, 2017; NMFS West Coast Region, ESA Recovery Plan for Snake River Sockeye Salmon
(Oncorhynchus nerka), June 8, 2015, pp. 1-431, https://repository.library.noaa.gov/view/noaa/16001; Columbia
Basin Partnership Task Force, A Vision for Salmon and Steelhead: Goals to Restore Thriving Salmon and
Steelhead to the Columbia River Basin, National Oceanic and Atmospheric Administration, Phase 2 Report of
the Columbia Basin Partnership Task Force of the Marine Fisheries Advisory Committee, October 2020, p. 161,
https://s3.amazonaws.com/media.fisheries.noaa.gov/2020-10/MAFAC_CRB_Phase2ReportFinal_508.pdf?null; L.A.
Fulton, Spawning Areas and Abundance of Steelhead Trout and Coho, Sockeye, and Chum Salmon in the
Columbia River Basin-Past and Present, NMFS, Special Scientific Report, No. 618, Washington, DC, December
1970, pp. 1-37, https://spo.nmfs.noaa.gov/SSRF/SSRF618.pdf.
Notes: DPS = distinct population segment; ESU = evolutionarily significant unit. Approximate mean abundances
(2010-2019; the most recent estimates available) for fall Chinook salmon include release mortalities.
Approximate mean abundances (2010-2019; the most recent estimates available) for spring/summer Chinook
salmon include Lower Granite River Dam passage plus Tucannon River escapement. Approximate mean
abundances (2010-2019; the most recent estimates available) for steelhead trout are based on passage from July
1 to June 30 the following year. NMFS calculated approximate mean abundance values from 2010 to 2019 as a
geometric mean, which is defined as the nth root of n products. Experts consider geometric means to be a
better measure than simple averages of central tendency for fish abundance data, which are typically skewed. The
geometric mean also smooths the contribution of periodic large run sizes that can inflate simple averages relative
to typical population values. Scientists typically select a 10-year period to represent an interval of sustained
abundance across multiple generational cycles. Geometric means do not provide exact values of abundance as
they have variance associated with them; NMFS typically does not report that variance in its assessments and
reports.
Factors Affecting Snake River Salmon and Steelhead Trout
Populations
Dams in the Columbia River Basin, and in the Snake River specifically, may change the natural
flows, temperature, and turbidity of rivers and may create barriers to salmon and steelhead trout
migration. These factors may alter habitat and affect water quality for fish species. Other
activities, apart from dams, may also affect salmon and steelhead trout populations. These
activities include climate change, drought, predation, development, and nonpoint and point source
pollution, among others. These activities may affect species by altering stream, tributary, and
estuary habitats; lowering water quality; and increasing predation of fish from pinnipeds,82 native
and non-native fishes, and colony nesting waterbirds.
In many cases, these activities affect fish populations throughout the Columbia River Basin, but
may be particularly impactful on endangered or threatened species. Also, some of these factors
have occurred consistently over time, but may have greater impacts in recent and future years.
Some factors may be sensitive to dam operations, while others may be less so. Some salmon and
steelhead trout runs are fished for commercial, tribal, and recreational uses. Harvest-related
mortality was a significant contributor to the initial decline of these species; however, this is not a
major contributor to the decline of salmon and steelhead trout today.83 The following sections
discuss selected key factors that affect Snake River salmon and steelhead trout populations.
82 Pinnipeds are aquatic mammals in the order Pinnipedia. Seals and sea lions are the most relevant pinnipeds for the
purposes of this report.
83 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022.
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Dams and Their Operations
Dams and their operations may change water quantity in rivers, alter natural flow rates and
temperature, and change turbidity.84 These alterations can change river structure and alter aquatic
and riparian habitat, which can affect salmon and steelhead trout species during their life cycles
and natural migrations.85 Dams structurally affect fish species by preventing migration and
causing entrainment in hydropower blades. For example, dams can make it more difficult for
adult fish to migrate upstream to spawning grounds, thus cutting salmon and steelhead trout off
from their once occupied spawning habitats. Operations that reduce water velocity behind dams,
often creating reservoirs, slow juvenile migrations, alter the food web, increase water temperature
and create habitat for native and non-native predators and competitors.86
Scientists note that the lower Snake River dams act as a barrier for fish swimming upstream
trying to access portions of their identified spawning habitat and for fish swimming downstream
to the ocean.87 In addition, some scientists note that passage through dam complexes (e.g.,
passage through fish ladders) can stress fish populations and possibly cause delayed mortality.88
They assert that the effect of dams on fish species varies with how many dams the fish must pass.
Populations of Chinook salmon and steelhead trout species in the Columbia River Basin that pass
through four or fewer dams have higher survival rates than those populations that must pass
through eight dams, such as Snake River spring/summer Chinook salmon.89 Scientists found that
summer steelhead trout originating in the Yakima subbasin, which must pass only four mainstem
dams, also exhibit greater survival rates than those originating in the Snake River Basin.90
Scientists calculate smolt-to-adult return rates (SARs) of Snake River salmon and steelhead trout
to estimate the effects of various factors on their population viability.91 An estimated minimum
SAR of 2% is required to consistently sustain populations, whereas an SAR of >2% is indicative
of population growth and an SAR of >4% is estimated to lead to a high likelihood of recovery.92
84 NMFS, Biological Opinion, 2020, p. 101.
85 NMFS, Recovery Plan, 2017, pp. 126, 140-149.
86 NMFS, Biological Opinion, 2020, p. 140. Northwest Power Council, Dams: Impacts on Salmon and Steelhead,
https://www.nwcouncil.org/reports/columbia-river-history/damsimpacts/. Adam J. Storch et al., “A Review of Potential
Conservation and Fisheries Benefits of Breaching Four Dams in the Lower Snake River (Washington, USA),” Water
Biology and Security, vol. 1 (2022) (hereinafter Storch et al., “Review of Potential Conservation and Fisheries
Benefits,” 2022).
87 NMFS, Biological Opinion, 2020, p. 299.
88 Storch et al., “Review of Potential Conservation and Fisheries Benefits,” 2022.
89 Storch et al., “Review of Potential Conservation and Fisheries Benefits,” 2022.
90 Storch et al., “Review of Potential Conservation and Fisheries Benefits,” 2022.
91 Smolt-to-adult return rate (SAR) is the survival rate of salmon and steelhead trout from when they are smolts to
when they return to a certain point as adults. SARs are an indicator of survival and population health for salmon and
steelhead populations. SARs in the Snake River are typically calculated for each of the listed population segments.
SARs for populations could be for wild fish only, hatchery-origin fish, or both combined. Michele DeHart et al.,
Comparative Survival Study of PIT-Tagged Spring/Summer/Fall Chinook, Summer Steelhead, and Sockeye 2023
Annual Report, Comparative Survival Study Oversight Committee and Fish Passage Center, December 2023,
https://www.fpc.org/documents/CSS/CSS%20Report%202023%20Final.pdf (hereinafter DeHart et al., Comparative
Survival Study, 2023).
92 D.R. Marmorek et al., Plan for Analyzing and Testing Hypotheses (PATH), ESSA Technologies, Ltd., Final Report
for Fiscal Year 1998, Vancouver, British Columbia, December 16, 1998, p. 41, http://rem-main.rem.sfu.ca/papers/
peterman/PATH_final_report_for_fiscal_year_1998.pdf; DeHart et al., Comparative Survival Study, 2023; David W.
Welch et al., “A Synthesis of the Coast-wide Decline in Survival of West Coast Chinook Salmon (Oncorhynchus
tshawytscha, Salmonidae),” Fish and Fisheries, vol. 22, no. 1 (2021), pp. 194-211 (hereinafter Welch et al., “A
Synthesis of the Coast-wide Decline in Survival of West Coast Chinook Salmon (Oncorhynchus tshawytscha,
Salmonidae),” 2021).
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These criteria reportedly have informed Northwest Power and Conservation Council regional
stock rebuilding goals for Snake River and upper Columbia River salmon and steelhead trout
(i.e., SARs in the 2-6% range).93
The annual Comparative Survival Study (CSS) measures the effects of hydropower operations on
juvenile and adult salmon and steelhead trout survival in the Columbia River System.94 The CSS
reported SARs for salmon and steelhead trout most recently in 2023.95 For the majority of wild
populations, current SAR estimates were <3.5%, while current SAR values for Upper Columbia
wild Sockeye salmon ranged from 2.5% – 9.6% depending on location.96 The CSS also predicted
that climate change, poor ocean conditions, and poor flow conditions (which is affected by dams)
would prevent salmon and steelhead trout populations from meeting SAR goals noted above.97
Some studies have characterized the SAR goals as being ambitious, and questioned the feasibility
of achieving them in light of these stressors.98 One study also noted the inability for some salmon
populations in more “pristine” conditions than in the Columbia River (e.g., southeast Alaska) to
achieve these SAR percentages, suggesting that larger scale environmental factors may be
impeding their productivity and recovery more broadly.99
The CSS reported that the most important factors influencing SARs for salmon and steelhead
trout are water transit time,100 the number of dam passages, and certain indices of ocean
conditions (e.g., upwelling, sea surface temperature).101 Other studies have emphasized the
importance of broad ocean drivers and harvest as key factors affecting SARs and salmon
production as well.102 Dam operations affect water transit times (e.g., fish bypasses and
93 Northwest Power and Conservation Council, Columbia River Basin Fish and Wildlife Program 2014, October 2014,
p. 29, https://www.nwcouncil.org/sites/default/files/2014-12_1.pdf; Welch et al., “A Synthesis of the Coast-wide
Decline in Survival of West Coast Chinook Salmon (Oncorhynchus tshawytscha, Salmonidae),” 2021.
94 DeHart et al., Comparative Survival Study, 2023. The annual Comparative Survival Study measures the effects of
hydropower operations on juvenile and adult salmon and steelhead trout survival in the Columbia River System; see
also B.P. Sanford and S.G. Smith, “Estimation of Smolt-to-Adult Return Percentages for Snake River Basin
Anadromous Salmonids, 1990-1997,” Journal of Agricultural, Biological, and Environmental Statistics, vol. 7 (2002),
pp. 243-263 (hereinafter Sanford and Smith, “Estimation of Smolt-to-Adult Return,” 2022).
95 DeHart et al., Comparative Survival Study, 2023, Appendix B, pp. B-1 to B-125.
96 DeHart et al., Comparative Survival Study, 2023, Appendix B, pp. B-1 to B-125.
97 DeHart et al., Comparative Survival Study, 2023; Sanford and Smith, “Estimation of Smolt-to-Adult Return,” 2022.
98 Welch et al., “A Synthesis of the Coast-wide Decline in Survival of West Coast Chinook Salmon (Oncorhynchus
tshawytscha, Salmonidae),” 2021; NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 3.
99 Welch et al., “A Synthesis of the Coast-wide Decline in Survival of West Coast Chinook Salmon (Oncorhynchus
tshawytscha, Salmonidae),” 2021; see also B. Dorner et al., “Spatial and Temporal Patterns of Covariation in
Productivity of Chinook Salmon Populations of the Northeastern Pacific Ocean,” Canadian Journal of Fisheries and
Aquatic Sciences, vol. 75, no. 7 (2018), pp. 1082-1095.
100 The Comparative Survival Study Oversight Committee and Fish Passage Center define water transit time as “the
time it takes the average particle of water to pass through a reservoir (or series of reservoirs). It measures water velocity
through a reservoir in [a] way that accounts for reservoir volume relative to the discharge at a dam. It is calculated by
dividing the reservoir volume relative to the discharge at a dam.” DeHart et al., Comparative Survival Study, 2023, p.
20.
101 DeHart et al., Comparative Survival Study, 2023.
102 Welch et al., “A Synthesis of the Coast-wide Decline in Survival of West Coast Chinook Salmon (Oncorhynchus
tshawytscha, Salmonidae),” 2021; N.J. Mantua et al., “A Pacific Interdecadal Climate Oscillation with Impacts on
Salmon Production,” Bulletin of the American Meteorological Society, vol. 78, no. 6 (1997), pp. 1069-1079; Steven L.
Haeseker et al., “Assessing Freshwater and Marine Environmental Influences on Life-Stage-Specific Survival Rates of
Snake River Spring-Summer Chinook Salmon and Steelhead,” Transactions of the American Fisheries Society, vol.
141, no. 1 (2012), pp. 121-138 (hereinafter Haeseker et al., “Assessing Freshwater and Marine Environmental
Influences on Life-Stage-Specific Survival Rates of Snake River Spring-Summer Chinook Salmon and Steelhead,”
2012).
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reservoirs), in most cases increasing them. Scientists note that increased water transit times may
disrupt the natural timing of ocean entry and have negative latent effects on fishes.103 The CSS
stated that water transit times of Snake River fish populations did not significantly improve
between 1994 and 2023.104 Furthermore, additional studies have related SARs and survival of
Snake River salmon with water transit time, the timing of ocean entry, and the percentage of river
flow spilled over dams.105
In some cases, dams and their operations can benefit fish species in a multiuse situation. Dams
can be operated to supplement low water flows and decrease water temperature downstream for
fish and their habitats during periods of drought.106 In multiuse systems where water is allocated
to the environment, agricultural uses, hydropower, and other uses, dams provide operators with
increased control over water flows. For example, one study asserted that managed flows were
better than natural flows for reducing non-native species and achieving societal needs (e.g.,
hydropower, agricultural water supply).107 This assertion was based on a comparison between
managed flows and simulated natural flows.
Some dam owners have constructed infrastructure to mitigate the effects of dams on fish (see
Figure 5 for systems specific to juvenile passage). For example, USACE has added surface
passage facilities such as spillway weirs, implemented surface passage structures, and modified
turbine designs to reduce entrainment at the lower Snake River dams to reduce juvenile
mortality.108 These systems can improve how and where fish maneuver through the river in the
presence of dams.109 Juvenile survival also is enhanced by bypass systems and turbine
improvement programs to help juveniles travel downstream to the ocean.110 Fish ladders allow
adult fish returning from the ocean to spawn to bypass dams. USACE constructed ladders when it
built the lower Snake River dams and have modified the ladders over time.
Dam owners also may modify operations to reduce fish mortality. For example, USACE adjusts
spill (i.e., the amount of water that is allowed to pass through spillways and over dams) at the
lower Snake River dams to improve the survival of juvenile fish passing through the dams.111
103 Ernest T. Smerdon et al., Managing the Columbia River: Instream Flows, Water Withdrawals, and Salmon Survival,
National Research Council, 2004, p. 94.
104 DeHart et al., Comparative Survival Study, 2023.
105 Haeseker et al., “Assessing Freshwater and Marine Environmental Influences on Life-Stage-Specific Survival Rates
of Snake River Spring-Summer Chinook Salmon and Steelhead,” 2012; Erin L. Rechisky et al., “Estuarine and EarlyMarine Survival of Transported and In-River Migrant Snake River Spring Chinook Salmon Smolts,” Scientific Reports,
vol. 2, no. 1 (2012), 448, pp. 1-9.
106 Kristen Sellheim et al., “Informed Water Management Alternatives for an Over-Allocated River: Incorporating
Salmon Life Stage Effects into a Decision Tree Process During Drought,” Fisheries Management and Ecology, vol. 27,
no. 5 (2020), pp. 498-516.
107 William Chen and Julian D. Olden, “Designing Flows to Resolve Human and Environmental Water Needs in a
Dam-Regulated River,” Nature Communications, vol. 8, no. 1 (December 18, 2017).
108 Surface passage structures allow fish to move through spillways and over dams, whereas bypass channels guide fish
around dams.
109 NMFS, Biological Opinion, 2020, p. 201.
110 USACE, “Lower Snake River Dams,” https://www.nww.usace.army.mil/Missions/Lower-Snake-River-Dams/.
111 NMFS, Biological Opinion, 2020, p. 140.
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Figure 5. Systems Used to Improve Juvenile Passage Through Dams
Source: National Marine Fisheries Service, “Juvenile Downstream Passage on the West Coast,”
https://www.fisheries.noaa.gov/west-coast/endangered-species-conservation/juvenile-downstream-passage-westcoast.
Habitat Loss and Alteration
Habitat loss affects salmon and steelhead trout populations, especially if it alters spawning or
rearing areas. It can be caused by many factors, including urbanization along stream and river
corridors; resource extraction, such as logging, mining, and agriculture; channelization of
streams; water withdrawals; and dams and other physical barriers that alter water flows. The
condition of salmon habitat varies throughout the Columbia River Basin. In protected areas, such
as federal wilderness areas, spawning and rearing habitat may remain in near-pristine condition.
In areas more accessible to humans, past and present human activities have left habitat in
conditions ranging from marginally to highly degraded. For instance, more than 70% of the
original marshes and spruce swamps of the Columbia River estuary (a key habitat used by
juvenile and adult salmon during their migration to and from the ocean) have been converted to
industrial, transportation, recreational, agricultural, or urban areas.112 Some scientists also note
various biological effects on habitats such as lower or excess nutrients in some tributaries. Habitat
degradation in the Snake River Basin leads to (1) reduced stream complexity and channel
structure, (2) excess fine sediment, (3) elevated summer water temperature, (4) diminished
streamflow during critical periods, (5) reduced floodplain connectivity and function, and (6)
degraded riparian condition.113
Estuary habitat degradation also affects fish. In the Columbia River estuary, downriver of the
Snake River, some scientists estimate that, in the last 100 years, mean river flow has declined
16% and peak spring flows have declined 44%.114 Lower flows into the estuary can alter habitat
112 NMFS, Recovery Plan, 2017, p. 187.
113 NMFS, Biological Opinion, 2020, p. 349.
114 NMFS, Columbia River Estuary ESA Recovery Plan Module for Salmon and Steelhead, NMFS Northwest Region.
Prepared for NMFS by the Lower Columbia River Estuary Partnership (contractor) and PC Trask Associates, Inc.,
subcontractor, Portland, OR, 2011, pp. 3-6 and 4-3, https://repository.library.noaa.gov/view/noaa/17401; NMFS, ESA
Recovery Plan for Snake River Fall Chinook Salmon (Oncorhynchus tshawytscha), NOAA, 2017.
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and cause mortality. For Snake River populations, the estimated mortality of juvenile salmon (not
due to predation) from habitat impacts in the estuary ranges from approximately 15% to 30%,
with greatest impacts observed for fall-run Chinook salmon and summer-run steelhead trout.115
Water Quality
Various activities, including agricultural, urban, and industrial activities, contribute pollutants to
the Columbia River Basin. For instance, excess nutrients from sewage or agricultural runoff helps
catalyze algal blooms that decrease the dissolved oxygen content in the water, causing hypoxia,
which can be lethal to fish.116 These factors, together with other chemical pollutants, can be
detrimental for salmonid growth, immune function, and survival.117
Temperature is another component of water quality that can affect the health of fish populations.
Low water flows, high air temperature, and other factors may cause high water temperatures. For
example, in 2015, high water temperatures led to significant mortality of Upper Columbia River
and Snake River sockeye salmon populations as these populations migrated through the rivers of
the Columbia River Basin.118 To address high water temperatures in the Columbia and lower
Snake Rivers, the U.S. Environmental Protection Agency (EPA) established the Columbia and
Lower Snake Rivers Temperature Total Maximum Daily Load (TMDL).119 The TMDL provides
information about the primary sources of temperature impairments in the Columbia River Basin.
With this information, federal, state, and tribal governments, and the public may engage on ways
to reduce temperatures in the Columbia and lower Snake Rivers, including as impacted by dams
and their operations. (For more information, see the text box below.)
Temperature Total Maximum Daily Load for the Columbia and
Lower Snake Rivers
The U.S. Environmental Protection Agency (EPA) established a temperature total maximum daily load (TMDL) for
the Columbia and lower Snake Rivers in 2020, pursuant to Section 303(d) of the Clean Water Act (33 U.S.C.
§1313(d)). The EPA established this TMDL after the states of Washington and Oregon identified portions of the
Columbia and lower Snake Rivers as impaired due to water temperatures that exceeded state water quality
standards. EPA found that water temperatures frequently exceeded values that protect salmonid and steelhead
trout migration, especially in August at two of four monitoring locations on the lower Snake River. (The warmest
temperatures in the Snake River have occurred in the lower part of the river.)
EPA’s TMDL analysis considered all known sources of temperature impairments in the lower Snake River. It found
that climate change and nonpoint source dam impacts are the dominant sources of impairment. According to the
EPA, warming trends since the 1960s have led to increases in water temperatures. The EPA also noted that dams
and their operations can cause higher sustained river temperatures in the summer, higher temperatures at the
water surface and in fish ladders, and delayed cooling in the fall. The EPA estimated that dams on the lower Snake
River have a warming impact on the mainstem river in the late-summer period.
115 Columbia Basin Partnership Task Force, A Vision for Salmon and Steelhead, 2020, p. 63.
116 John R. Waldman and Thomas P. Quinn, “North American Diadromous Fishes: Drivers of Decline and Potential for
Recovery in the Anthropocene,” Science Advances, vol. 8, no. 4 (January 28, 2022).
117 Lyndal Johnson et al., “Persistent Organic Pollutants in Juvenile Chinook Salmon in the Columbia River Basin:
Implications for Stock Recovery,” Transactions of the American Fisheries Society, vol. 142, no. 1 (2013), pp. 21-40;
James P. Meador et al., “Altered Growth and Related Physiological Responses in Juvenile Chinook Salmon
(Oncorhynchus tshawytscha) from Dietary Exposure to Polycyclic Aromatic Hydrocarbons (PAHs),” Canadian
Journal of Fisheries and Aquatic Sciences, vol. 63, no. 10 (October 2006).
118 Lisa G. Crozier et al., “Snake River Sockeye and Chinook Salmon in a Changing Climate: Implications for
Upstream Migration Survival During Recent Extreme and Future Climates,” PLoS ONE, vol. 15, no. 9 (2020).
119 U.S. Environmental Protection Agency (EPA), Columbia and Lower Snake Rivers Temperature Total Maximum
Daily Load, August 13, 2021, https://www.epa.gov/system/files/documents/2022-06/tmdl-columbia-snake-temperatureerrata-update-05102022.pdf.
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Dam owners can use temperature control strategies to manage water temperatures. For example, deep reservoirs
with temperature control structures (e.g., Dworshak Dam above the lower Snake River dams) can release cold
water and reduce temperatures over substantial distances downstream (e.g., to the upper portion of the lower
Snake River in the summer). National Pollutant Discharge Elimination System permits issued to be consistent with
the TMDL include a requirement to implement temperature control strategies and meet the load allocations in
the Columbia and lower Snake Rivers TMDL.
Sources: EPA, Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load, August 13, 2021,
https://www.epa.gov/columbiariver/tmdl-temperature-columbia-and-lower-snake-rivers; EPA, “Discharge
Permits for Federal Hydroelectric Projects in the Lower Snake River,” https://www.epa.gov/npdes-permits/
discharge-permits-federal-hydroelectric-projects-lower-snake-river.
Predation
Salmon and steelhead trout have numerous natural predators, including birds, pinnipeds (e.g.,
seals, sea lions), orcas, fish, and terrestrial mammals (e.g., bears).120 Many of the predator-prey
dynamics between salmonids and other species are affected by anthropogenic changes in the
Columbia River Basin. For example, construction and operation of the Columbia River System
and disposal of dredge material in the tributaries of the Columbia and Snake Rivers and in the
Columbia River estuary have altered species’ habitats. These altered habitats support a wide range
of predator species, including native and non-native predatory fish species, such as North
pikeminnow (Ptychocheilus oregonensis); predatory birds, such as terns, cormorants, gulls,
mergansers, and pelicans; and marine mammals.121
In addition, seals and sea lions are key predators of salmon in the mouth of the Columbia River.
These pinnipeds consume salmon entering the ocean and may lower salmon populations.122 Sea
lions are also observed to concentrate downstream of the Bonneville Dam to feed on salmon and
steelhead trout staging for passage through fish ladders.123 Populations of pinnipeds in the Pacific
Ocean have increased substantially since the Marine Mammal Protection Act (MMPA; P.L. 92522; 16 U.S.C. §§1361-1423h) was enacted in 1972.124 The MMPA lowered pinniped harvests by
humans, resulting in increases to some pinniped populations. To address pinniped predation of
salmon, the MMPA allows the Secretary of Commerce to authorize the intentional lethal removal
of “individually identifiable pinnipeds” causing significant negative impacts to certain salmonid
species.125
120 NMFS, Recovery Plan, 2017, p. 156.
121 NMFS, Recovery Plan, 2017, p. 156.
122 Daniel Schindler et al., Pinniped Predation on Salmonids in the Washington Portions of the Salish Sea and Outer
Coast, Washington State Academy of Sciences, November 2022, p. 7, https://app.leg.wa.gov/ReportsToTheLegislature/
Home/GetPDF?fileName=
Pinniped%20Predation%20on%20Salmonids%20in%20the%20Washington%20Portions%20of%20the%20Salish%20S
ea%20and%20Outer%20Coast_5d43c6d6-3aad-442a-9271-0315d351eaf2.pdf (hereinafter Schindler et al., Pinniped
Predation, 2022).
123 Columbia Basin Partnership Task Force, Phase 1 and 2 Report. USACE, 2024 Evaluation of Pinniped Predation on
Adult Salmonids and Other Fish in the Bonneville Dam Tailrace, March 2025, https://public.crohms.org/tmt/
documents/FPOM/2010/Task%20Groups/Task%20Group%20Pinnipeds/
Final_2024_USACE_Pinniped_Annual_Report.pdf.
124 Schindler et al., Pinniped Predation, 2022. For more information on the Marine Mammal Protection Act, see CRS
Report R47892, The Marine Mammal Protection Act (P.L. 92-522): Primer and Issues for Congress, by Anthony R.
Marshak.
125 16 U.S.C. §1389. The statute includes salmonid fishery stocks that have been listed as threatened or endangered
species under the ESA. NOAA, Marine Mammal Protection Act Section 120 Pinniped Removal Program,
(continued...)
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Drought
Drought in the western United States plays a role in salmon survival. Drought causes streams to
run low and warm during certain times of the year, which can impact fish populations. Several
high water-temperature events provide examples of fish kills of salmon in the Pacific Northwest,
as discussed in the “Water Quality” section above. Drought also can alter migration signals for
salmon. For example, a study of salmon in California found that drought-induced low flows and
warming altered migration signals for young coho salmon and led to a smaller timeframe for
migration.126 According to scientists, salmon that begin migration on a false signal, such as an
isolated rain event during a drought, can become stranded and die in portions of streams or rivers
that unexpectedly dry up because of the drought rather than increasing in water flow.127
Climate Change
Climate change influences and exacerbates many of the existing threats to salmonids. Some
scientists assert that climate change will increasingly imperil certain salmon populations.128 For
example, some scientists note that climate change is increasing water temperature, which can
directly harm fishes, increase the range and populations of invasive species, and alter food
webs.129 Climate change also may exacerbate low flow rates in rivers or increase flooding from
high-precipitation events. In addition, sea level rise might result in tidal wetland habitat loss in
the Columbia River floodplain, which might affect salmon populations.130
Some scientists provide a mixed assessment of the possible effects of climate change and existing
conditions on salmon. For example, they contend that the effects of climate change on freshwater
habitats of salmon may affect salmon species and populations differently at certain timescales. In
some cases, they assert that climate change may lead to an increase in Chinook salmon survival in
the short term, partially related to the species’ adaptive capacity, but that the effects of climate
change may be detrimental in the long term.131
Climate change also may affect ocean habitat in ways that may impact salmon. Climate change
may increase the frequency and magnitude of marine heat waves, change the intensity and timing
of coastal upwelling, increase hypoxia events, and increase ocean acidification.132 For example,
rising sea surface temperatures could harm migrating salmon in the Pacific Northwest.
Additionally, coho salmon returns to Puget Sound, WA, and to coastal waters off Washington and
https://www.fisheries.noaa.gov/west-coast/marine-mammal-protection/marine-mammal-protection-act-section-120pinniped-removal. For more background, see CRS In Focus IF11045, Sea Lion Predation on Columbia River Salmon
and Steelhead, by Anthony R. Marshak.
126 Brian Kastl et al., “Migration in Drought: Receding Streams Contract the Seaward Migration Window of
Endangered Salmon,” Ecosphere, vol. 13, no. 12 (December 2022), pp. 1-11.
127 For example, approximately 65,000 wild salmon in Canada reportedly perished due to false migration signals and
dried up streams caused by drought, according to some scientists. See Leyland Cecco, “Thousands of Salmon Found
Dead as Canada Drought Dries Out River,” Guardian, October 5, 2022, https://www.theguardian.com/environment/
2022/oct/05/canada-dead-salmon-drought-british-columbia.
128 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 9; and Zanna Stutz, “Salmon Don’t
Have Time for Us to Fix the Climate”: The Politics of Climate Change and Dam Breaching on the Lower Snake River,”
(undergraduate thesis, Dartmouth College, 2024), pp. 1-125.
129 Crozier et al., “Climate Vulnerability Assessment,” 2019.
130 Columbia Basin Partnership Task Force, Phase 1 and 2 Report.
131 Xiao Zhang et al., “On the Variable Effects of Climate Change on Pacific Salmon,” Ecological Modelling, vol. 397,
no. 1 (2019), pp. 95-106.
132 Lisa G. Crozier et al., “Climate Change Threatens Chinook Salmon Throughout Their Life Cycle,” Communications
Biology, vol. 4, no. 222 (2022) (hereinafter Crozier et al., “Climate Change Threatens Chinook Salmon,” 2022).
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Oregon were among the lowest on record following the 2013-2015 Pacific marine heatwave.133
Rising marine temperatures also may alter the marine community, leading to changes in
zooplankton, krill, squid, and other fish that salmon consume.134
Conserving and Restoring Snake River Fishes
Federal, state, local, and tribal stakeholders have conducted activities to conserve and restore
Snake River salmon and steelhead trout. Most federal activities aimed at restoring salmon and
steelhead trout in the Columbia River Basin are implemented by NOAA and BPA, although other
agencies also contribute to these efforts.135 This section summarizes selected federal restoration
efforts for conserving salmon and steelhead trout populations in the Columbia River Basin.
Bonneville Power Administration Fish and Habitat Initiatives
BPA has a fish and wildlife program that aims to protect, enhance, and mitigate adverse effects to
fish and wildlife in the Columbia River Basin from the Columbia River System. BPA funds
projects to improve fish passage through the Columbia River System, increase fish populations
through hatcheries, monitor fish populations, and increase the conservation of wildlife and fish
populations through land acquisitions and habitat restoration. BPA designed its fish and wildlife
program to be consistent with provisions under the Northwest Power Act, the ESA, and other
environmental laws, in addition to honoring the federal trust responsibility (including upholding
tribal treaty rights). The program also is guided by the Northwest Power and Conservation
Council (Council) program, discussed below.
The Northwest Power Act expanded BPA’s responsibilities, adding a directive to mitigate the
effects of the federal hydropower system on fish and wildlife in the Columbia River Basin.136 The
act also directed that fish and wildlife in the Columbia River Basin should be protected and
enhanced.137 The Northwest Power Act authorized the creation of the Council and directed it to
develop a program to conserve and improve fish and wildlife.138 BPA addresses its Northwest
Power Act responsibilities for fish and wildlife mitigation by funding the implementation of the
Council’s Columbia River Basin Fish and Wildlife Program (FWP). The FWP has a set of goals
and objectives (see Table 4) and a strategy to achieve them. The Council’s fish and wildlife
conservation activities are described in the Columbia River Basin Fish and Wildlife Program,
Draft 2026 Program 2014.139
133 William Peterson, Nicholas Bond, and Marie Robert, “The Blob Is Gone but Has Morphed into a Strongly Positive
PDO/SST Pattern,” North Pacific Marine Science Organization (PICES) Press, vol. 24, no. 2 (2016), pp. 46-47, 50.
134 Crozier et al., “Climate Change Threatens Chinook Salmon.”
135 In addition to funding fish and wildlife conservation, BPA, NMFS, and other federal agencies fund fish and wildlife
restoration in the Columbia River Basin. These federal agencies are part of the Columbia Basin Federal Caucus and
include USACE, Reclamation, EPA, FWS, NMFS, the U.S. Forest Service, and others. See Office of Management and
Budget, Analytical Perspectives, Budget of the United States Government, Fiscal Year 2025, Columbia River Basin
Federal Crosscut Report, Office of Management and Budget, March 11, 2024, https://www.govinfo.gov/app/details/
BUDGET-2025-PER/BUDGET-2025-PER-6-3-3; Columbia River Basin Federal Caucus, “The Columbia River Basin
Federal Caucus,” https://salmonrecovery.gov.
136 16 U.S.C. §839.
137 16 U.S.C. §839.
138 Two people from each of Idaho, Montana, Oregon, and Washington are appointed to be on the Northwest Power and
Conservation Council. 16 U.S.C. §839b.
139 Northwest Power and Conservation Council, Columbia River Basin Fish and Wildlife Program, Draft 2026
Program, Council Document 2025-5, December 17, 2025, https://www.nwcouncil.org/fs/19694/2025-5.pdf.
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Table 4. Columbia River Basin Fish and Wildlife Program Goals and Objectives
Program Area
Description
Anadromous Salmon and Steelhead Goal
and Objectives
Focus on increasing adult salmon and steelhead runs and abundance
All Other Native Aquatic Focal Species
Goal and Objectives
Focus on protecting, enhancing, and mitigating impacts on other
native aquatic species affected by the FCRPS, such as white sturgeon
and Pacific lamprey
Wildlife Goal and Objectives
Focus on mitigation for wildlife losses caused by the FCRPS
Ecological Goal and Objectives
Address environmental conditions and processes to conserve the
ecosystems that support native anadromous and resident fish and
wildlife adversely affected by the FCRPS
Communication, Assessment, and
Coordination Goal and Objectives
Aim to inform and involve the public in the Fish and Wildlife
Program, track and report program implementation, and make
program-related information and data available
Source: Northwest Power and Conservation Council, 2020 Addendum to the 2014 Columbia River Basin Fish and
Wildlife Program, Council Document 2020-9, October 2020, https://www.nwcouncil.org/sites/default/files/20209.pdf.
Note: FCRPS = Federal Columbia River Power System.
Restoration activities undertaken by BPA and other parties also have also been managed through
the Columbia Basin Fish Accords.140 BPA partnered with seven Tribes, two federal agencies, and
three states to sign the Columbia Basin Fish Accords in 2008. The accords lay out plans for
federal funding to address fish operations, habitat, and hatchery projects over a 10-year period.
Federal funding was provided to Tribes and states over the period. Several entities have extended
their accords multiple times; the most recent extension was to September 30, 2025.141 The accords
were allowed to expire on September 30, 2025; it is unclear if future accords between BPA,
states, federal agencies, and Tribes will materialize in the future.
BPA Fish and Wildlife Activities. BPA funds three types of fish and wildlife projects: (1) fish
passage structures; (2) hatchery facility construction and maintenance, including in the Snake
River Basin; and (3) land acquisition and maintenance, which involves projects that aim to
protect and enhance fish and wildlife habitat throughout the Columbia River Basin. BPA
coordinates its fish and wildlife priorities with the Council, federal resource management
agencies (e.g., NMFS, USACE, Reclamation), states, Tribes, and other stakeholders. These
investments and corresponding activities are in BPA strategic asset management plans.142
BPA funds fish and wildlife activities in various ways. BPA incurs direct program costs for fish
and wildlife projects for ESA-listed species, reimburses USACE and Reclamation for the
agencies’ operation and maintenance costs for fish and wildlife species, repays the U.S. Treasury
for capital expenditures incurred by the federal government for constructing hatcheries and fish
passage projects, and purchases power to supply customer demand when fish operations prevent
electricity generation at its dams. In addition, BPA incurs opportunity costs when water is spilled
over the dam to support ESA-listed species instead of using that water for power generation. BPA
previously estimated that its annual investments in fish and wildlife program areas from 2015 to
140 BPA, “Columbia Basin Fish Accords,” https://www.bpa.gov/environmental-initiatives/efw/columbia-basin-fish-
accords.
141 For more information and text of accords, see BPA, “Columbia Basin Fish Accords,” https://www.bpa.gov/
environmental-initiatives/efw/columbia-basin-fish-accords.
142 BPA’s Strategic Asset Management Plans are at BPA, “Strategic Asset Management Plans,” https://www.bpa.gov/
about/finance/strategic-asset-management-plans.
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2024 ranged from approximately $450 million to $1.4 billion per year.143 In FY2024, the majority
of BPA fish and wildlife expenditures were related to habitat restoration and protection (44%);
research, monitoring, and evaluation (29%); and hatchery production (15%).144
NOAA Pacific Salmon Management and Conservation Activities
NOAA management and conservation efforts for Pacific salmon and steelhead trout are guided by
recovery plans and status reviews for listed species;145 conservation plans; a fishery management
plan for Pacific Salmon off the West Coast as developed by the Pacific Fishery Management
Council;146 and recommendations, treaties, and input from the Pacific States Marine Fisheries
Commission, state agencies, and stakeholders.147
NOAA collaborates with several entities to manage salmon and steelhead trout fisheries in the
Columbia River Basin. Management is authorized and guided, in part, by the 2018-2027 United
States v. Oregon Management Agreement.148 The agreement’s purpose is to protect and rebuild
upper Columbia River salmon and steelhead trout runs while providing harvests for the Columbia
River Treaty Tribes (CRT Tribes) and non-treaty fisheries.149 The agreement sets up a process for
management that is guided by CRT Tribes and selected states (Idaho, Oregon, and Washington)
pursuant to state laws, treaties such as the Columbia River Compact and Pacific Salmon Treaty,
and federal laws such as the ESA and Magnuson-Stevens Fishery Conservation and Management
Act (MSA; 16 U.S.C. §§1801 et seq.). Fisheries managers meet throughout the year to review
information, set regulations and seasons for fishing, and plan the operation of fisheries. The
agreement extends to 2027.150
143
BPA, 2024 Report on Bonneville Power Administration’s Fish and Wildlife Expenditures, October 2, 2025,
https://www.nwcouncil.org/fs/19438/2025-4.pdf. Hereafter, BPA, 2024 Report on Bonneville Power Administration’s
Fish and Wildlife Expenditures.
144 The remainder of the expenditures was for law enforcement, coordination, data management, predator removal, and
harvest augmentation. BPA, 2024 Report on Bonneville Power Administration’s Fish and Wildlife Expenditures.
145 Pacific salmon management in this context applies to salmon species occurring in the state and federal waters of
California, Oregon, Washington, and Idaho. Recovery plans created by NOAA exist for all listed Snake River species
of salmon and steelhead trout.
146 As developed by the Pacific Fishery Management Council and implemented by NOAA. Pacific Fishery
Management Council, Pacific Coast Salmon Fishery Management Plan for Commercial and Recreational Salmon
Fisheries off the Coasts of Washington, Oregon, and California as Revised Through Amendment 23, December 2022,
pp. 1-84, https://www.pcouncil.org/documents/2022/12/pacific-coast-salmon-fmp.pdf/.
147 The Pacific States Marine Fisheries Commission (PSMFC) is an interstate compact agency that helps state resource
agencies and the fishing industry manage ocean resources in a five-state region that includes California, Oregon,
Washington, Idaho, and Alaska. Each state is represented by three Commissioners in the Commission. PSMFC,
“Pacific States Marine Fisheries Commission,” https://relief.psmfc.org/.
148 This agreement was created under ongoing litigation in United States v. Oregon, Civil No. 68-513-MO (D. Or.). For
more information and text of the agreement, see NMFS, FWS, Bureau of Indian Affairs, Endangered Species Act (ESA)
Section 7(a)(2) Biological Opinion and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish
Habitat Response: Consultation on Effects of the 2018-2027 U.S. v. Oregon Management Agreement, NMFS
Consultation Number WCR-2017-7164, https://media.fisheries.noaa.gov/dam-migration/s7-_usvoregon_20182027_mgmagmnt__final_signed.pdf.
149 Columbia River Treaty Tribes are Tribes that are parties to the Columbia River Treaty and include the Confederated
Tribes of the Warm Springs Reservation of Oregon, the Confederated Tribes of the Umatilla Indian Reservation, the
Nez Perce Tribe, and the Confederated Tribes and Bands of the Yakama Nation.
150 NMFS, “2018-2027 United States v. Oregon Management Agreement: Frequently Asked Questions,”
https://www.fisheries.noaa.gov/west-coast/sustainable-fisheries/2018-2027-united-states-v-oregon-managementagreement.
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NOAA, through NMFS, also conserves ESA-listed salmon and steelhead trout species through
several actions, including the following:
•
•
•
•
•
Planning and Implementing Recovery Actions. NMFS prepares and
implements recovery plans for Snake River listed species, as required by the
ESA.151 Recovery plans contain actions that aim to restore listed species so they
no longer need protection under the ESA. The plans do not create binding
obligations for NMFS under the ESA but instead are organizing tools for guiding
and coordinating recovery efforts across multiple stakeholders (i.e., federal,
tribal, state, local, and private entities).152
Restoring Habitat. NMFS aims to improve wetlands, restore spawning and
rearing habitat, and improve fish passage, among other goals, for Pacific salmon,
steelhead trout, and other fish species.
Implementing Hatchery Programs (see the text box below).
Improving Fish Passage. NMFS improves upstream and downstream passage
for salmon and steelhead trout, including by implementing culverts, fish screens,
and tide gates.153
Conducting Reintroduction Efforts. The ESA authorizes the reintroduction of
listed species, such as salmon, under Section 10(j) of the act.154
Salmon and Steelhead Trout Hatcheries
Hatcheries aim to provide short-term conservation benefits for declining fish populations by increasing fishery
production during periods of low natural abundance. Some experts also recommend multiple restoration
approaches to restore declining fish populations that may include hatcheries and concurrent focus on habitat,
genetic diversity of wild fish populations, and other factors for long-term conservation success. Further, some
scientists suggest that potential adverse impacts from hatcheries to wild fish populations’ genetic diversity (i.e.,
from interbreeding of potentially genetically inferior hatchery-reared individuals with wild individuals) might limit
the efficacy of restoration efforts and limit certain wild fishes’ adaptive capacity to changing climate.
Federal, state, and tribal entities produce hatchery salmon and steelhead trout in the Snake River and Columbia
River Basin. Hatchery production for salmon and steelhead trout in the basin peaked at 200 million juvenile fish
per year in the late 1980s and early 1990s and has reduced to approximately 140 million juvenile fish per year
since 2010 due to concerns over protecting the genetic diversity of wild fish. Annual hatchery production in the
Columbia River Basin is mostly composed of fall Chinook salmon (45%), with additional production of spring
Chinook salmon (24%) and coho salmon (12%). Hatchery-origin fish account for approximately two-thirds of the
total return of adults to the Columbia River Basin and comprise the majority of salmon and steelhead trout
harvested in the basin.
Sources: Robin S. Waples, “Dispelling Some Myths About Hatcheries,” Fisheries, vol. 24, no. 2 (1999), pp. 12-21;
Columbia Basin Partnership Task Force, A Vision for Salmon and Steelhead: Goals to Restore Thriving Salmon and
Steelhead to the Columbia River Basin, National Oceanic and Atmospheric Administration, Phase 2 Report of the
Columbia Basin Partnership Task Force of the Marine Fisheries Advisory Committee, October 2020, pp. 53, 149;
J.E. Siegel et al., “Environmentally Triggered Shifts in Steelhead Migration Behavior and Consequences for Survival in
the mid-Columbia River,” PLoS ONE, vol. 16, no. 5 (2021), article e0250831, p. 19; and John R. McMillan et al., “A
Global Synthesis of Peer-Reviewed Research on the Effects of Hatchery Salmonids on Wild Salmonids,” Fisheries
Management and Ecology, vol. 30, no. 5 (2023), pp. 446-463.
151 16 U.S.C. §1533(f).
152 See “Recovery Planning and Implementation” section at NMFS, “Pacific Salmon and Steelhead: ESA Protected
Species,” https://www.fisheries.noaa.gov/species/pacific-salmon-and-steelhead.
153 In addition to annual appropriations, the Infrastructure Investment and Jobs Act (P.L. 117-58) provided NMFS with
funding to improve fish passage. For instance, see funding announcements at NMFS, “Two NOAA Fish Passage
Funding Opportunities Now Open, One Focused on Tribes,” October 30, 2024, https://www.fisheries.noaa.gov/featurestory/two-noaa-fish-passage-funding-opportunities-now-open-one-focused-tribes.
154 16 U.S.C. §1539(j).
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These conservation actions are implemented through several programs and activities within
NMFS, including the Pacific Coastal Salmon Recovery Fund,155 as well as Pacific salmon under
the Protected Resource Science and Management budget line.156
Salmon and steelhead trout conservation is informed by documents and plans generated by
NMFS. For example, NMFS’s 2022 report titled Rebuilding Interior Columbia Basin Salmon and
Steelhead outlined actions aiming to achieve the Columbia River Basin Partnership’s mid-range
goals for salmon and steelhead trout abundance for 2050 (i.e., those exceeding low-range
abundance thresholds and representing progress toward high-range goals).157 The Columbia Basin
Partnership has identified low-, mid-, and high-range natural-origin population abundance
goals.158 The low-range abundance goals are generally consistent for recovery under the ESA,
whereas the high-range abundance goals are consistent with “healthy and harvestable stocks.”159
The “healthy and harvestable” standard of recovery is different from the standard set for species
listed under the ESA. In the context of the ESA, NMFS generally defines the standard of recovery
for ESA-listed salmon and steelhead trout as the abundance necessary to limit extinction risk to
5% over a 100-year timeframe.160 The standard for “healthy and harvestable” stock levels are
generally set at three-to-five-times the minimum abundance levels necessary to ensure the longterm survival of the population, stock, or species.161
In its 2022 report, NMFS qualitatively assigned priorities for rebuilding Columbia River basin
salmon and steelhead trout populations based on five criteria: level of extinction risk; current
spatial structure and diversity; importance to tribal communities; habitats available for essential
life-cycle needs; and resilience of habitat to climate change.162 The rebuilding priorities assigned
were “high,” “higher,” and “highest” (NOAA considered priority for rebuilding to be at least high
for all populations).163 NMFS asserts that the Snake River spring/summer Chinook salmon and
Snake River steelhead trout populations are “critically important to Columbia River basin Tribes,
as well as to the economy and overall ecological health of the region.”164 NMFS designated that
155 For more information about the Pacific Coastal Salmon Recovery Fund, see CRS In Focus IF13096, The Pacific
Coastal Salmon Recovery Fund, by Anthony R. Marshak.
156 For more information on the implementation of salmon and steelhead conservation activities within NMFS, see
NOAA, National Oceanic and Atmospheric Administration Budget Estimates: Fiscal Year 2026, 2025,
https://www.noaa.gov/sites/default/files/2025-06/NOAA%20FY26%20Congressional%20Justification.pdf.
157 The Columbia Basin Partnership was a Task Force chartered by NOAA’s Marine Fisheries Advisory Committee in
2017 to develop a common vision and goals for the Columbia River Basin’s salmon and steelhead. NMFS, Rebuilding
Interior Columbia Basin Salmon and Steelhead, 2022.
158 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022.
159 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022. NOAA specifically states that “rebuilding
healthy and harvestable stocks is a substantially more ambitious goal than meeting ESA recovery standards, which are
intended to achieve delisting, or the mandates of ESA Section 7(a)(2), which are meant to avoid jeopardizing the
continued existence of ESA-listed species.”
160 NMFS, ESA Recovery Plan for Idaho Snake River Spring/Summer Chinook Salmon and Snake River Basin
Steelhead, Chapter 5, West Coast Region, November 2017, pp. 73, 114, 184, 219, 253,
https://media.fisheries.noaa.gov/2021-12/final-idaho-mu-recovery-plan-chapter-5.pdf; NMFS, “Endangered and
Threatened Species; Recovery Plans,” 74 Federal Register 50165-51072, September 30, 2009.
161 For listed salmon and steelhead trout, these minimum abundance levels (i.e., low-range natural production goals)
are, in most cases, consistent with ESA delisting goals. Columbia Basin Partnership Task Force, A Vision for Salmon
and Steelhead, 2020, pp. 44-45 and Haley Ohms, “Salmon Recovery Must be Built on Ambitious, Achievable Goals
Instead of Bare Minimums,” Trout Magazine, June 21, 2023, https://www.tu.org/magazine/conservation/barriers/damremoval/salmon-recovery-must-be-built-on-ambitious-achievable-goals-instead-of-bare-minimums/.
162 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, pp. 5-6.
163 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 6.
164 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 6.
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rebuilding of those two Snake River populations to healthy and harvestable levels is “highest”
priority.165 The report recommended several actions that aim to achieve abundance goals,
including the following:
•
•
•
•
•
•
•
•
Reducing direct and indirect mortality resulting from mainstream dams on the
Snake River;
Restoring the Snake River through dam breaching;
Managing predator and competitor species associated with salmon and steelhead
trout;
Restoring tributary and estuarine habitat and improving water quality;
Enhancing passage and reintroducing fish in certain areas that are blocked,
including the upper Columbia River;
Securing a more functional salmon ocean ecosystem;
Addressing effects of climate change on fish populations and habitat; and
Reforming hatcheries and harvest levels.166
Columbia River Basin Tribal History and
Current Activities
Steelhead trout, Pacific lamprey, and other native fish have played a key role in the history,
culture, religion, and economic development of Indigenous peoples in the Pacific Northwest.
Salmon, in particular, has provided sustenance, strengthened social and cultural ties, and afforded
economic opportunities. According to the Columbia River Inter-Tribal Fish Commission
(CRITFC), “salmon are at the center of the diets, cultures, and religions of Columbia Plateau
tribes.”167 Fishing is central to many tribal ceremonies and traditions.
Due to their historical connection to salmon and other native fish, some of the Tribes in the
Pacific Northwest reserved rights to continue hunting, fishing, or gathering on lands they ceded to
the federal government by treaty. Many Tribes in the Columbia River Basin retain treaty reserved
rights to hunt or fish in “usual and accustomed” places.168 Courts have affirmed these rights even
when the usual and accustomed places are not located within the boundaries of a reservation.169
(See Figure 6 for a map of the Columbia River Basin that includes federal and tribal lands.)
Courts also have held that the right to fish by extension includes a right to protect the habitat on
which the fish rely.170 In addition, courts have recognized the federal trust responsibility, which
165 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022. Furthermore, p. 6 of the report identifies
the rebuilding of Snake River fall Chinook salmon and sockeye salmon as “higher priority” among northwest salmon
populations.
166 NMFS, Rebuilding Interior Columbia Basin Salmon and Steelhead, 2022, p. 16.
167 Columbia River Inter-Tribal Fish Council, “Tribal Salmon Culture,” https://critfc.org/salmon-culture/tribal-salmonculture/.
168 For example, see Treaty with the Yakima, 1855, Art. 3; Treaty with the Tribes of Middle Oregon, 1855; Treaty with
the Walla Walla, Cayuse, etc., 1855, Art. 1; and Treaty with the Nez Perces, 1855. Art. III.
169 See, for example, United States v. Winans, 198 U.S. 371 (1905) and United States v. Washington, 520 F.2d 676 (9th
Cir. 1975) (“the Boldt Decision”). The Supreme Court also ruled that treaty Tribes are entitled to a maximum of 50%
of the harvestable fish (Washington v. Washington State Commercial Passenger Fishing Vessel Ass’n, 443 U.S. 658
(1979)).
170 United States v. Washington, 506 F. Supp. 187, 203 (W.D. Wash. 1980) and United States v. Washington, 853 F.3d
946, 963 (9th Cir. 2017).
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can include obligations to protect tribal treaty rights, lands, assets, and resources on behalf of
Tribes and tribal members.171
Throughout the 20th century, many Tribes in the Columbia River Basin opposed the construction
and operation of dams because the dams would limit their access to historic tribal lands and offreservation fishing rights.172 According to USACE, 19 Tribes may be affected by the Columbia
River System.173 The lower Snake River dams primarily affect five Tribes: the Nez Perce Tribe,
the Confederated Tribes and Bands of the Yakama Indian Nation, the Confederated Tribes of the
Umatilla Indian Reservation, the Confederated Tribes of the Warm Springs Reservation of
Oregon, and the Shoshone-Bannock Tribes of the Fort Hall Reservation.174 As outlined in the
“Factors Affecting Snake River Salmon and Steelhead Trout Populations” section of this report,
the lower Snake River dams block fish species from accessing portions of their once occupied
spawning habitat, which some Tribes have argued has reduced tribal access to the fish guaranteed
by treaties.175 Some Tribes have been parties to lawsuits relating to federal dam operations and
fish management in the basin, including recent litigation in response to the operation of the
Columbia River System (see below section “Recent Litigation Challenging Agency Actions
Related to the Lower Snake River Dams”).
171 The federal trust responsibility is a legal obligation under which the United States, through treaties, acts of
Congress, and court decisions, “has charged itself with moral obligations of the highest responsibility and trust” toward
Tribes. Seminole Nation v. United States, 316 U.S. 286, 296-297 (1942). For a general overview of the trust
relationship, see United States v. Jicarilla Apache Nation, 564 U.S. 162 (2011).
172 See, for example, Columbia River Inter-Tribal Fish Commission (CRITFC), Tribal Circumstances & Impacts from
the Lower Snake River Project on the Nez Perce, Yakama, Umatilla, Warm Springs, and Shoshone Bannock Tribes,
p. 3, https://critfc.org/wp-content/uploads/2021/10/circum_exec.pdf (hereinafter CRITFC, Tribal Circumstances &
Impacts).
173 “Executive Summary” in USACE, Reclamation, and BPA, 2020 EIS, p. 11.
174 Washington Governor’s Office, Lower Snake River Dams Stakeholder Engagement Report, p. 22,
https://www.washingtonpolicy.org/library/docLib/LSRD-Report.pdf.
175 NMFS, Biological Opinion, 2020, p. 299. See also CRITFC, Tribal Circumstances & Impacts, p. 9.
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Figure 6. Federal and Tribal Lands in the Columbia River Basin
Source: CRS modification of map obtained from U.S. Government Accountability Office, Columbia Basin Fish and
Wildlife Activities, 04-602, June 2004, p. 8, https://www.gao.gov/assets/gao-04-602.pdf.
As a way to secure their fishing rights, many Tribes in the Pacific Northwest have sought to
influence regional fish management through intertribal fish commissions, advocacy targeting dam
operations or removal, and restoration work. Tribes have used intertribal fish commissions such
as the Northwest Indian Fisheries Commission and the CRITFC.176 Furthermore, the MSA
requires the Pacific Fishery Management Council to include a representative from a Pacific
Northwest Tribe with fishing rights.177 In addition to advocating for optimizing spill to benefit
salmon at the dams and restoring salmon behind blocked areas in the basin, some Tribes have
advocated for removal of the lower Snake River dams.178 Several area Tribes also have
established hatcheries to supplement fish stock in the basin.179
176
Pacific Fishery Management Council, “Tribes,” https://www.pcouncil.org/fishingcommunities/tribes/.
177 16 U.S.C. §1852(b)(5). The required representative is appointed by the Secretary of Commerce. Representation
rotates among the Tribes in consideration of individuals’ qualifications, the rights of the Tribes involved, judicial cases
that set forth the exercise of those rights, and geography.
178 National Congress of American Indians (NCAI), “Calling on the President and Congress to Invest in Salmon and
River Restoration in the Pacific Northwest,” NCAI Resolution #AK-21-009, 2021. See also Affiliated Tribes of
Northwest Indians (ATNI), “Calling on the President of the United States and the 117 th Congress to Seize the Once-ina-Lifetime Congressional Opportunity to Invest in Salmon and River Restoration in the Pacific Northwest, Charting a
Stronger, Better Future for the Northwest, and Bringing Long-Ignored Tribal Justice to Our Peoples and Homelands,”
ATNI Resolution #2021-23.
179 See the list of tribal restoration efforts in U.S. Government Accountability Office, Columbia River Basin: Additional
Federal Actions Would Benefit Restoration Efforts, GAO-18-561, August 2018, pp. 87-92, https://www.gao.gov/assets/
gao-18-561.pdf.
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The Department of the Interior (DOI) and other federal agencies have collaborated with Pacific
Northwest Tribes to ensure compliance with tribal treaty rights and other laws providing for tribal
management of fisheries and access to fish harvests. For example, DOI’s Bureau of Indian Affairs
provides funding to support tribal fish hatching, rearing, and stocking programs.180 The Pacific
Northwest Tribes operate 45 hatcheries and rearing facilities that benefit from this funding. The
Nez Perce Tribe has also assumed full responsibility for fish production at the Dworshak National
Fish Hatchery, which USACE built in the 1960s on the tribal reservation, near the Dworshak
Dam.181
Congress has enacted laws to mitigate Columbia River Basin dam impacts on tribal treaty rights.
For example, in 1938, Congress passed the Mitchell Act, which directed the Secretary of
Commerce to establish one or more “salmon-cultural stations” in the Columbia River Basin.182 In
1988, Congress directed the Secretary of the Army to acquire land next to the Bonneville
Pool/Dam (along the Columbia River) to provide certain Tribes with “treaty fishing access
sites.”183 These sites were then transferred to DOI.184
Recent Litigation Challenging Agency Actions
Related to the Lower Snake River Dams
Operating the Columbia River System dams has the potential to affect species listed under the
ESA and the Columbia River Basin environment in general. Due to these potential effects, the
action agencies generally must consult with NMFS pursuant to Section 7 of the ESA and conduct
environmental reviews pursuant to NEPA before finalizing proposed changes to the system’s
operating plans.185
Both the ESA and NEPA impose certain procedural requirements on federal agencies when they
propose or modify actions. The ESA also imposes a substantive constraint on federal agencies;
Section 7 of the ESA generally requires federal agencies, such as the action agencies for the
Columbia River System, to ensure—in consultation with the U.S. Fish and Wildlife Service
(FWS) and NMFS (together, the Services)—that their actions do not jeopardize listed species or
adversely modify critical habitat.186 If the action agency or the relevant Service determines that a
proposed federal action is likely to adversely affect listed species or critical habitat, the relevant
Service issues a BiOp analyzing whether the action as proposed would in fact jeopardize the
continued existence of a listed species or adversely modify its critical habitat.187 If the Service
concludes that the proposed action would jeopardize listed species, the Service is required to
180 DOI, Bureau of Indian Affairs, Budget Justifications and Performance Information Fiscal Year 2026, Bureau of
Indian Affairs, https://www.doi.gov/sites/default/files/documents/2025-12/bia-2026-greenbook508.pdf.
181
FWS, “Dworshak National Fishery,” https://www.fws.gov/fish-hatchery/dworshak.
182 Mitchell Act, May 11, 1938, 52 Stat. 345 and 25 C.F.R. §248. NOAA administers the Mitchell Act program and
supports hatcheries. The term salmon cultural station is not defined in statute (NOAA, Final Environmental Impact
Statement to Inform Columbia River Basin Hatchery Operations and the Funding of Mitchell Act Hatchery Programs,
2014, https://media.fisheries.noaa.gov/2021-11/mitchell-act-hatcheries-feis-final.pdf).
183 P.L. 100-581 and 25 C.F.R. §247.
184 25 C.F.R. §247.1.
185 16 U.S.C. §1536(a)(2); 42 U.S.C. §4332.
186 16 U.S.C. §1536(a)(2); 42 U.S.C. §4332.
187 16 U.S.C. §1536(b)(3). If the FWS and NMFS (together, the Services) or action agencies determine that the agency
action is not likely to adversely affect listed species or critical habitat, the consultation process can be concluded
without a BiOp.
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suggest reasonable and prudent alternatives (RPAs) to the proposed action that the Service
believes would avoid jeopardy.188 The Service also must recommend mitigation measures to limit
the action’s impacts on the listed species.189
Due to the potential impacts on listed salmon and steelhead trout species, the effects of operation
plans for the FCRPS—or, more recently, for the Columbia River System specifically—on listed
species and their designated critical habitats have been analyzed through the ESA Section 7
consultation process. Since 1992, the action agencies have consulted with NMFS on the potential
effects of various proposed action plans for the FCRPS or the Columbia River System subset of
dams, depending on the plan, and NMFS has issued a series of BiOps assessing those impacts.190
The protective measures for the fish species that NMFS has included in RPAs or mitigation
measures for those BiOps often require the action agencies to reduce energy generation or
irrigation supply from the Columbia River System.191
Under the APA, stakeholders affected by federal agency actions, such as modifications to dam
operating plans, generally may challenge the agency action or any related BiOps or NEPA
documents in court.192 A variety of stakeholders have repeatedly challenged operating plans and
associated review documents for the FCRPS or Columbia River System, resulting in a number of
decisions that required the action agencies and NMFS to revisit the plans, BiOps, and NEPA
reviews.193 Courts have repeatedly determined that the BiOps NMFS has prepared with respect to
the FCRPS are inconsistent with the ESA and/or the APA.194 Although courts have consistently
remanded the BiOps to NMFS for reconsideration, the courts generally have allowed the federal
agencies to keep operating the FCRPS in accordance with all or portions of each BiOp, or a
modified version thereof, to allow operations to continue while NMFS reconsidered its analysis in
the BiOp.195
Although numerous different cases have been filed since NMFS’s BiOps were first challenged in
the 1990s, the current litigation over Columbia River System operations and the associated BiOp
and EIS stems from a complaint originally filed in 2001 by NWF and an array of other
188 16 U.S.C. §1536(b)(3).
189 16 U.S.C. §1536(b)(4)(ii).
190 For copies of and information about the BiOps since 2000, see, for example, Federal Caucus, NOAA Fisheries
Biological Opinion for Operation and Maintenance of the Columbia River System Operations,
https://www.salmonrecovery.gov/BiologicalOpinions/FCRPSBiOp.aspx; NOAA Fisheries, Federal Columbia River
Power System Biological Opinion, updated October 11, 2023, https://www.fisheries.noaa.gov/west-coast/endangeredspecies-conservation/federal-columbia-river-power-system-biological-opinion.
191 The reduction in electricity generation for fish and wildlife protection within the Columbia River Basin led to $893
million in costs in FY2024. Foregone power revenues cost $37 million and power purchases (e.g., buying power from
wholesale markets when water was being spilled for fish protection instead of being used for electricity generation)
cost $856 million. For comparison, BPA estimates total costs for fish and wildlife protection operations for that year
(inclusive of the above values) at $1.369 billion. The majority of other costs ($271 million) were for direct fish and
wildlife program expenses (see such actions described in “Bonneville Power Administration Fish and Habitat
Initiatives”). Northwest Power and Conservation Council, 2024 Report on Bonneville Power Administration’s Fish and
Wildlife Expenditures, August 5, 2025, https://www.nwcouncil.org/reports/2025-4/.
192 5 U.S.C. §704.
193 For example, an original complaint and eight subsequent supplemental complaints have been filed in NWF v.
NMFS, No. 3:01-CV-00640, in the U.S. District Court for the District of Oregon since 2001.
194 See, for example, Idaho Department of Fish & Game v. NMFS, 850 F. Supp. 886 (D. Or. 1994), vacated as moot by
Idaho Dep’t of Fish & Game v. NMFS, 56 F.3d 1071 (9 th Cir. 1995); NWF v. NMFS, 254 F. Supp. 2d 1996 (D. Or.
2003); NWF v. NMFS, 2005 WL 1278878 (D. Or. May 26, 2005); Am. Rivers v. NOAA Fisheries, 2006 WL 1455629
(D. Or. May 23, 2006); NWF v. NMFS, 839 F. Supp 2d 1117 (D. Or. 2011).
195 See, for example, NWF v. NMFS, 2005 WL 2488447 (D. Or. Oct. 7, 2005); Am. Rivers v. NOAA Fisheries, 2006
WL 2792675 (D. Or. Sept. 26, 2006); NWF v. NMFS, 839 F. Supp. 2d 1117 (D. Or. 2011).
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nongovernmental advocacy organizations in federal court in the District of Oregon.196 The 2001
complaint in National Wildlife Federation v. National Marine Fisheries Service challenged a
2000 BiOp issued by NMFS pursuant to Section 7 of the ESA.197 In the 2000 BiOp, NMFS
assessed the potential impact of an operating plan for the FCRPS on species listed under the ESA
and their designated critical habitats.198 In 2003, the district court remanded the 2000 BiOp to
NMFS to address deficiencies related to the action area and mitigation actions.199
NWF has supplemented the complaint eight times since it was initially filed to address new
BiOps for revised operation plans. Each of the complaints includes allegations against the action
agencies or agencies that issued BiOps under the ESA in connection with operation plans, for
either the FCRPS as a whole or the Columbia River System specifically.200 The claims generally
have alleged violations of the APA, the ESA, and, more recently, NEPA. The most recent
supplemental complaint was filed in January 2021 and raised claims related to NMFS’s 2020
BiOp for operations of the Columbia River System as well as the action agencies’ 2020 EIS and a
2020 ROD.201
This section provides an overview of recent litigation over various federal agency actions related
to the FCRPS or Columbia River System operations (with a focus on decisions related to the
lower Snake River dams), as well as how the agencies have adjusted the operation plans to
address successive court orders and changing natural and political environments.
196 Complaint for Declaratory and Injunctive Relief, National Wildlife Federation (NWF) v. National Marine Fisheries
Service (NMFS), No. 3:01-CV-00640 (D. Or. May 3, 2001). The same parties have filed a series of petitions against
BPA in the U.S. Court of Appeals for the Ninth Circuit (Ninth Circuit) for BPA’s related RODs. See, for example,
Petition for Review, Am. Rivers v. BPA, No. 08-74597 (9th Cir. Nov. 6, 2008) (challenging BPA 2008 ROD); Petition
for Review, Am. Rivers v. BPA, No. 10-72710 (9th Cir. Sept. 2, 2010) (challenging BPA 2010 ROD); Petition for
Review, Am. Rivers v. BPA, No. 14-71475 (9th Cir. May 27, 2014) (challenging BPA 2014 ROD). Section 9(e)(5) of
the Northwest Power Act requires that certain challenges against BPA’s activities be filed in the Ninth Circuit. 16
U.S.C. §839f(e). As a result, although claims against NMFS, Reclamation, and the Army Corps are filed in federal
district court, related claims against BPA must be filed in the Ninth Circuit if they fall under the types of challenges
addressed by Section 9(e)(5) of the Northwest Power Act. The parties explained in a filing submitted to the court that
they brought these challenges “as a precaution in the event that the district court proceedings do not provide Petitioners
with the full relief sought.” Reply in Support of Motion for Limited Reopening of Petition, Pacific Coast Federation of
Fishermen’s Associations v. BPA, No. 20-73761, at 5 (9th Cir. Jan. 27, 2026). The petitioners noted that the Ninth
Circuit had stayed each of these petitions until the district court proceedings were resolved and that, in each case, the
district court had ultimately granted the declaratory and injunctive relief sought and the petitioners had accordingly
agreed to dismiss the petitions against BPA. Reply in Support of Motion for Limited Reopening of Petition, Pacific
Coast Federation of Fishermen’s Associations v. BPA, No. 20-73761, at 5 (9th Cir. Jan. 27, 2026).
197 See Opinion and Order, NWF v. NMFS, No. 3:01-CV-00640 (D. Or. May 7, 2003).
198 Opinion and Order, NWF v. NMFS, No. 3:01-CV-00640 (D. Or. May 7, 2003).
199 NWF v. NMFS, 254 F. Supp. 2d 1196 (D. Or. 2003).
200 The action agencies generally have prepared operation plans for the entire FCRPS. The 2020 operation plan—and
associated BiOp, environmental impact statement, and record of decision—addressed only the operation of the
Columbia River System.
201 Eighth Supplemental Complaint for Declaratory and Injunctive Relief, NWF v. NMFS, No. 3:01-CV-00640 (D. Or.
Jan. 20, 2021). As with prior supplemental complaints, the same parties filed a parallel petition for review of BPA’s
ROD in the Ninth Circuit. Petition for Review, Pacific Coast Federation of Fishermen’s Associations v. BPA, No. 2073761 (9th Cir. Dec. 23, 2020). The petition for review has generally remained administratively closed while the
federal district court litigation proceeded or was similarly stayed while settlement negotiations proceeded. See, for
example, Order, Pacific Coast Federation of Fishermen’s Associations v. BPA, No. 20-73761 (9th Cir. Oct. 29, 2021)
(directing the clerk to temporarily close the docket for administrative purposes until August 2, 2022).
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Litigation over FCRPS Biological Opinions and Supplements from
2000 to 2014
NMFS issued the 2020 BiOp in response to a 2016 court order, after the court concluded that
NMFS’s second supplement to its 2008 BiOp for FCRPS operations violated the ESA, APA, and
NEPA. NWF had supplemented its complaint to challenge the 2008 BiOp after NMFS issued it in
May 2008.202 Before the court issued a decision on the 2008 BiOp, the federal defendants
requested—and the court granted—a limited, voluntary remand of the 2008 BiOp. NMFS
released a supplemental BiOp in May 2010 (2010 Supplement). NWF then amended its complaint
to challenge both the 2008 BiOp and 2010 Supplement.203
The district court concluded that the portion of the 2008 and 2010 BiOps addressing operations
through the end of 2013 complied with the ESA, identifying “specific and beneficial mitigation
measures” to address effects on species.204 However, for the portion of the BiOp addressing
operations between 2014 and 2018, the court held that NMFS relied on “habitat mitigation
measures that are neither reasonably specific nor reasonably certain to occur, and in some cases
not even identified.”205 The court remanded the 2008 and 2010 BiOps for further consultation on
post-2013 operations.206 The court order required NMFS to produce a supplement by January 1,
2014, that considered “whether more aggressive action, such as dam removal and/or additional
flow augmentation and reservoir modifications are necessary to avoid jeopardy.”207
In response to the court’s order, NMFS issued a second supplement in January 2014 (2014
Supplement) to the 2008 BiOp. The 2014 Supplement concluded, as the 2008 BiOp had, that the
agencies could avoid jeopardizing listed species through RPAs.208 The 2014 Supplement included
RPA measures that had been included in the 2008 BiOp and 2010 Supplement as well as habitat
mitigation projects that the action agencies had identified for implementation in 2014-2018.209
Following the issuance of the 2014 Supplement, the plaintiffs amended their complaint to
challenge the 2014 Supplement under the ESA and the APA and, for the first time, included a
claim for violating NEPA.210 The action agencies had not prepared a NEPA analysis for the 2014
202 Fourth Supplemental Complaint for Declaratory and Injunctive Relief, NWF v. NMFS, No. 3:01-CV-00640 (D. Or.
July 14, 2008). NWF amended the complaint further in September 2008 to include additional actions by and
information related to NMFS and to add Reclamation and USACE as defendants. Fifth Supplemental Complaint for
Declaratory and Injunctive Relief, NWF v. NMFS, No. 3:01-CV-00640 (D. Or. Sept. 12, 2008).
203 Sixth Supplemental Complaint for Declaratory and Injunctive Relief, NWF v. NMFS, No. 3:01-CV-00640 (D. Or.
Sept. 8, 2010).
204
NWF v. NMFS, 839 F. Supp. 2d 1117, 1121 (D. Or. 2011).
205 NWF v. NMFS, 839 F. Supp. 2d at 1125.
206 NWF v. NMFS, 839 F. Supp. 2d at 1130.
207 NWF v. NMFS, 839 F. Supp. 2d at 1130.
208 NMFS, Endangered Species Act Section 7(a)(2) Supplemental Biological Opinion: Consultation on Remand for
Operation of the Federal Columbia River Power System, January 14, 2014, p. 36, https://www.fisheries.noaa.gov/
resource/document/supplemental-consultation-remand-operation-federal-columbia-river-power-system.
209 NMFS, Endangered Species Act Section 7(a)(2) Supplemental Biological Opinion: Consultation on Remand for
Operation of the Federal Columbia River Power System, January 14, 2014, p. 33, https://www.fisheries.noaa.gov/
resource/document/supplemental-consultation-remand-operation-federal-columbia-river-power-system.
210 Seventh Supplemental Complaint for Declaratory and Injunctive Relief, NWF v. NMFS, No. 3:01-CV-00640 (D.
Or. July 9, 2014).
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Supplement. The agencies instead relied on existing NEPA documents that had been prepared for
prior operation plans for the FCRPS and other related actions.211
In May 2016, the district court held that the 2014 Supplement to the 2008 BiOp violated the ESA,
the APA, and NEPA.212 In concluding that the BiOp violated the ESA, the court cited flaws in
NMFS’s conclusion that protected species could be “trending toward recovery” even if the overall
population levels remained critically low.213 The court also considered NMFS’s habitat
improvement data “too uncertain” to rely upon and found that NMFS did not properly analyze the
effects of climate change.214
The court held that the action agencies violated NEPA by failing to prepare a new EIS to support
the decisions in their RODs about how they planned to operate the FCRPS pursuant to the 2014
Supplement. The court observed that, in conducting their NEPA analysis on remand, the action
agencies would have to consider reasonable alternatives that may have to include the impacts and
benefits of removing one or more of the four lower Snake River dams.215
Although the court concluded that the 2014 Supplement was arbitrary and capricious, it opted not
to vacate the BiOp. Instead, on July 6, 2016, the court remanded the BiOp and RODs to the
agencies to reconsider their actions and issue a new BiOp and RODs consistent with the ESA, the
APA, and NEPA.216 In the interim, the court ordered that the 2014 Supplement would govern the
operations of the FCRPS.
2020 Biological Opinion, Environmental Impact Statement, and
Record of Decision
In response to the court’s order and a presidential memorandum dated October 19, 2018,217
NMFS issued a new final BiOp (2020 BiOp) for operation of the Columbia River System in July
2020.218 The 2020 BiOp determined that Columbia River System operations would not jeopardize
listed species and identified reasonable and prudent measures to minimize the impacts of
211 See USACE, Northwestern Division, Supplemental Record of Consultation and Statement of Decision: NOAA
Fisheries’ 2014 Supplemental Biological Opinion Endangered Species Act Section 7(a)(2) Supplemental Biological
Opinion Consultation on Remand for Operation of the Federal Columbia River Power System, February 28, 2014,
p. 10; Reclamation, Pacific Northwest Region, 2014 Supplemental Decision Document Following the January 2014
NOAA Fisheries Supplemental Consultation on Operation of the Federal Columbia River Power System, 11 Bureau of
Reclamation Projects in the Columbia Basin, and ESA Section 10(a)(1)(A) Permit for Juvenile Fish Transportation
Program, June 11, 2010, pp. 23-24, https://www.usbr.gov/pn/fcrps/documents/2014supbiopdecision.pdf; BPA, Record
of Decision Following NOAA’s January 2014 Supplemental Biological Opinion to the May 2008 FCRPS Biological
Opinion and May 2010 Supplemental Biological Opinion for Operat
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