The Northwest Power Act. Pacific Northwest Electric Power Planning and Conservation Act, Pub. L. No. 96-501. (1980).
“. . . conservation and enhancement of the great migratory fish and wildlife populations of the Pacific Northwest, something of great concern to the sportsmen and conservationists of this Nation, are for the first time, a matter of urgent priority under this legislation. They are placed on a par with other purposes for Federal facilities in this area. If the fish populations of the Pacific Northwest are to be restored to the sportsmen, the Indians and the commercial fishermen, this is the mechanism which will do it.” 126 Cong. Rec. H10680 (Rep. Dingell)
2 Wilderness Areas. Wild & Scenic Rivers. National Recreation Areas. Within the Snake River Basin is the largest contiguous wilderness and roadless land complex and largest expanse of pristine and near pristine salmon habitat in the coterminous United States. This 14 million-acre area includes more than 4.4 million acres in 6 Wilderness Areas, more than 700 miles in 12 Wild and Scenic Rivers, and nearly 1 million acres within 2 National Recreation Areas.
Protecting wild salmon was a primary purpose of the laws creating all these areas. For example, legislation establishing the Sawtooth National Recreation Area in 1972 has as its first purpose "the protection and conservation of the salmon and other fisheries."
The Central Idaho Wilderness Act of 1980 states: "...these wildlands and a segment of the Salmon River should be incorporated within the National Wilderness Preservation System and the National Wild and Scenic Rivers System in order to provide statutory protection for the lands and waters and the wilderness-dependent wildlife and the resident and anadromous fish which thrive within this undisturbed ecosystem…” Excerpted from http://nwric.org/documents/The_NW_Big_Short.pdf
Native American Indian treaty-reserved rights. In multiple treaties with the U.S. numerous tribes and bands of Native American Indians ceded vast areas of territory to the U.S. at the point of a gun, e.g., the so-called 1855 Stevens Treaties. However, many reserved their rights to fish for salmon. In 1905 the U.S. Supreme Court upheld these rights saying salmon were “not much less necessary to the Indians than the atmosphere they breathed.” United States v. Winans, 198 U.S. 371 (1905).
Of course, all such treaty promises were broken and ignored by the federal agencies, the Northwest Power and Conservation Council and the NW congressional delegation—all hell bent on protecting the ill-designed pork barrel dams on the lower Snake River, no matter what treaties or laws say, or how much damage the dams cause.
4 Columbia River System Operations Final Environmental Impact Statement, U.S. Army Corps of Engineers, Bureau of Reclamation and Bonneville Power Administration, July 2020. Lower Snake River Juvenile Salmon Migration Feasibility Report/Environmental Impact Statement, U.S. Army Corps of Engineers, February 2002.
5 Fact Sheet BPA invests in ﬁsh and wildlife, Bonneville Power Administration, January 2019.
6 The Endangered Species Act. A Biological Opinion is the document required by the Endangered Species Act in which NOAA is to identify the factors responsible for the salmon being listed, and to define measures that must be taken to ensure those causative factors don’t jeopardize the future recovery of the listed species sufficiently to avert extinction. It is not, as some mistakenly think, the “recovery plan” required by the Act. Not that that mattered to NOAA Fisheries, which argued that the ESA requires only that a recovery plan be prepared, not that the fish actually have to be recovered. You read that correctly.
In August 2011, U.S. District Court Judge James Redden rejected the 2008/2010 BiOp as being made of much the same scofflaw stuff as the previous versions. "As the parties are well aware, the  BiOp was a cynical and transparent attempt to avoid responsibility for the decline of listed Columbia and Snake River salmon and steelhead." 2005 WL 1278878 (D.Or.)
U.S. District Court Judge Redden remanded the BiOp and NOAA Fisheries appealed; the district court remand was upheld by the Ninth Circuit Court of Appeals.
"At its core, the 2004 BiOp amounted to little more than an analytical sleight of hand, manipulating the variables to achieve a “no jeopardy” finding. Statistically speaking, using the 2004 BiOp's analytical framework, the dead fish were really alive.” 524 F.3d 917 Ninth Circuit Court of Appeals.
On May 6, 2016, U.S. District Judge Michael Simon rejected the agencies’ next new-improved BiOp as inadequate. He ordered NOAA, as well as the Corps and Bureau of Reclamation, back to the drawing board, and that their next ESA BiOp must also follow the National Environmental Policy Act.
"The Federal Columbia River Power System remains a system that 'cries out' for a new approach and for new thinking . . ." ". . . it may well require consideration of the reasonable alternative of breaching, bypassing, or removing one or more of the four Lower Snake River dams. This is an action that NOAA Fisheries and the action agencies have done their utmost to avoid considering for decades." Case No. 3:01-cv-0640-SI Opinion and Order.
7 See, e.g., the discussion of the following item 3 beginning on page 24 of http://nwric.org/documents/DOE_IG_petition.pdf:
3. Bonneville upper management uses federal funds to bribe Native American Indian and state governments in an effort to influence the federal judge in the ESA litigation and to subvert the salmon restoration provisions of the Northwest Power Act and other federal laws.
See also https://www.bpa.gov/efw/FishWildlife/CBFA/Pages/default.aspx.