Technical Recommendation 9 (formerly Adult Salmon Passage)

Adult Fish Migration

Use stored cold water, additional ladders, ladder improvements and ladder maintenance to enhance mainstem adult passage; incorporate 24-hour video fish counting.

Current Status

The construction and operation of mainstem hydroelectric dams continue to impair adult salmonid and lamprey migration to spawning locations in the Columbia River Basin. The dams have resulted in higher water temperatures unsuitable for salmon; hazardous passage through dams via fish ladders; fallback at fish ladder exits; and increased opportunities for salmon predators.

Recent survival rates indicate an improvement over those reported in the 1995 Plan. From 2009 through 2011, the survival of adult fish passing eight Federal Columbia River Power System (FCRPS) dams in the Columbia River Basin (Bonneville–Lower Granite dams) ranged as shown below. The FCRPS Biological Opinion (BiOp) targets, issued in compliance with Endangered Species Act, are shown in parentheses. These targets are to be met each year and are not averages. The rates do not account for increased predation on adults, particularly below Bonneville Dam.

  • Snake River spring chinook – 88 to 92% (BiOp target 91%) 1986-2012 figure
  • Upper Columbia spring chinook – 88 to 97% (BiOp target 90.1% only for Bonneville–McNary)
  • Snake River sockeye – 67 to 83% (BiOp target 81.1%)
  • Snake River steelhead – 75 to 83% (BiOp target 90.1%)
  • Snake River fall chinook – 85 to 88% (BiOp target 81%) 1986-2012 figure

Also, upstream survival for some salmon stocks appears to be increasing slightly over time. The adjacent figures for Snake River spring/summer chinook and Snake River fall chinook show upstream survival based on conversion rates.

The mid-Columbia dams (Wells, Rocky-Reach, Rock Island, Wanapum and Priest Rapids) are not included in the FCRPS BiOp; rather they are regulated by the FERC licensing process. The National Marine Fisheries Service (NMFS) biological opinions associated with these FERC licenses assumes no more that 2% adult passage mortality across the concrete of each dam. However, NMFS does not require these assumptions to be measured.

More information about adult fish passage and migration is provided in the 1995 Adult Salmon Passage recommendation and in the new technical recommendation Predation.


Operators of the Federal Columbia River Power System took actions related to recommendations in the 1995 Spirit of the Salmon Plan for cold-water flow augmentations from Dworshak Dam during the summer, fishway modifications to improve the upstream migration habitat for adult salmonids, and 24-hour fish counts to provide for more precise management data. They are briefly evaluated below, and several newer issues are described.

Water temperature: In the early 2000s, the region formalized a process which uses technical personnel from tribal, state and federal agencies—called the Technical Management Team (TMT)—to regulate the release of cold water at Dworshak to help assure that state water quality standards are met (i.e., to stay below 68 ° F). Through regional processes, salmon managers and agencies annually manage the reservoir between elevations 1600 and 1535 (65 feet) for release in July and August for flow augmentation and temperature control. In the 2004 Snake River Basin Adjudication, the Nez Perce Tribe reserved an additional 15 feet of drawdown (to as low as 1520), previously used in July/August, for release in September (or earlier if the tribe deems necessary).

Fishway modifications: Multiple fishway modifications have been added to FCRPS dams since 1995, improving adult passage. Adult attraction flows through fishways were increased at Ice Harbor, McNary and John Day dams. New serpentine sections were added to John Day Dam in 2004 to reduce adult leaping and injury in the upper sections of the ladder. Sea lion exclusion devices were added to the ladder entrances at Bonneville. (Sea lion predation is also addressed through hazing and other management actions.)

Fish counting: To improve fish counting, the hydraulics at count stations at John Day, Bonneville and The Dalles dams were improved reducing delay and milling of fish. In addition, PIT (passive integrated transponder) tag detectors are now at Bonneville, McNary, Lower Granite and Ice Harbor dams to allow for counting 24 hours a day. PIT tag counting allows for calculations on the effects of juvenile outmigration on adult returns (by route) and reservoir survivals for individual fish.

Fallback: Adult fallback has been reduced by changing project procedures at Bonneville to give priority to operating Powerhouse II, which moves downstream generation flow away from adult fish passage exits. At The Dalles Dam, the addition of a spill wall and changed spill patterns has decreased adult fall back (although this was a beneficial side effect of other efforts). McNary Dam still has large issues with fallback with winter steelhead because no safe fallback route is available during the non-spill season when these adults are present. Regional managers are trying to find a safer downstream route of passage to address this issue.

Kelt downstream passage: Currently, there is no regional strategy for downstream passage of Snake River and mid-Columbia kelts. The safest passage occurs through open surface routes, sluiceways and spillways during their outmigration, which usually starts in late February. Due to costs, many of these passageways are closed during parts of the season. The 2008 BiOp, which relies on kelt survival improvements, has allowed regional negotiations on improving and securing kelt passage at certain projects. CRITFC negotiated improved passage for kelts at Bonneville and The Dalles dams and is currently reviewing other critical locations.

Independent inspection and monitoring: After September 11, 2001, security measures have limited the ability for independent tribal monitoring at the dams.

Lamprey structural improvement: Lamprey structural improvements are being installed at many ladders. Ladder improvements to benefit salmon have been co-designed to assist lamprey during their upstream passage as well. Lamprey-focused improvements are being tested to assure they are not detrimental to adult salmon passage. See the updated technical recommendation Lamprey.

Mid-Columbia passage: No significant adult passage improvements have been made since 2001 at the mid-Columbia PUD projects. Neither dam passage nor reach survival are monitored at these projects.

New and Modified Actions

While the actions implemented since 1995 incrementally improved adult salmon passage survival rates, they did not meet the BiOps’ annual targets. Additional actions need to be implemented to meet BiOp targets.

  • Fish facilities should have full components of spare parts and backup systems.
  • Additional ladders should be added at Lower Granite and Little Goose dams to give them two each, ensuring adequate passage should one ladder fail and cause adult blockage, as occurred in 2013 at Lower Granite Dam.
  • Additional adult PIT tag monitoring locations should be added at John Day, The Dalles, Lower Monumental and Little Goose dams to better identify losses in the FCRPS system. Similarly, additional PIT tag monitoring locations should be investigated for the mid-Columbia PUD dams that do not have them so that losses can be identified in that reach.
  • Increase PIT tagging in the upper Columbia River, in accordance with consensus regional technical recommendations, to allow for comparisons of smolt-to-adult returns (SARs) for Snake River and upper Columbia populations.
  • Monitoring systems for the adult fish facilities should be fully automated and not require operators to make manual adjustments.
  • Install an adequate adult fishway trash rake system at Bonneville Powerhouse II; the system should protect lamprey and be easily maintained.
  • Ensure adequate auxiliary water supply systems at critical fish ladders, i.e., the Dalles, Little Goose and Lower Granite dams to ensure ladder functionality in instances where the primary water supply system fails.
  • Add shade cloth to adult ladders where needed to aid in reducing temperature difference within ladders and at exits, which can impede adult migration.
  • Review mid-Columbia project licenses to determine if improvements similar to those at FCRPS dams can be made at mid-Columbia dams.

Other actions:

  • Integrate adult lamprey passage assessment and needs into a new anadromous fish migration and passage recommendation in a new Spirit of the Salmon Plan. Until then, see updated technical recommendation Lamprey.
  • Continue improving and installing lamprey dam passage structures.
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