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Commentaries and editorials

Issue 20: Comments Calling for
Breaching Dams on Lower Snake River

by NOAA Fisheries
FCRPS Biological Opinion, May 5, 2008

Comment 20-A
The Save Our Wild Salmon Coalition and the Nez Perce Tribe suggest that to avoid jeopardy and adverse modification of critical habitats, NOAA Fisheries should issue a reasonable and prudent alternative (RPA) for the FCRPS that features removal of the four lower Snake River dams.

Response 20-A
NOAA Fisheries did not include lower Snake River dam breaching in its reasonable and prudent alternative for the FCRPS and did not conclude that this action or other actions beyond those in the RPA were necessary to avoid jeopardy and adverse modification of critical habitat. The RPA covers hydro system configuration and operations, juvenile transportation, tributary and estuary habitat restoration, hatchery improvements, and an expanded research, monitoring, and evaluation program to guide future actions. In addition, NOAA Fisheries has included in the 2008 RPA only measures actions that are within the authority of the Action Agencies and that are reasonably certain to occur. Dam breaching does not meet that standard.

Only four of 13 listed salmon and steelhead migrate past the Snake River dams, and dam removal would have virtually no effect on nine of the ESUs. Twelve ESUs have seen significant improvement in terms of annual adult returns since 2000 under recent management actions. The most improved is wild Snake River fall Chinook.

In the 2000 FCRPS Biological Opinion, NOAA Fisheries considered the likely effects of dam removal on ESU health. NOAA Fisheries found that the effects of Snake River dam breaching on the four affected species depended almost entirely on assumptions about delayed, or latent, mortality of in-river migrants that is expressed below Bonneville Dam. If that mortality is relatively low, or if it is not eliminated by breaching four of the eight mainstem dams encountered by those species, then breaching resulted in little or no benefit compared to operations under the 2000 FCRPS Biological Opinion's RPA. On the other hand, if post-Bonneville mortality caused by hydrosystem passage is high and dam removal eliminates most or all of it, the potential benefits of dam breaching would be significant. The magnitude of latent mortality remains unknown, as evidenced by the ISAB's (2007b) recent review of available evidence. They concluded that "the hydrosystem causes some fish to experience latent mortality, but [the ISAB] strongly advises against continuing to try to measure absolute latent mortality. Latent mortality relative to a damless reference is not measurable. Instead, the focus should be on the total mortality of in- river migrants and transported fish, which is the critical issue for recovery of listed salmonids." The RPA includes RM&E actions to monitor total mortality (smolt-to-adult returns) and includes hydro actions.

A seven-year study by the Corps of Engineers reached a similar conclusion about dam breaching in 2002. The Corps' independent, peer-reviewed study said dam breaching by itself would not recover the fish and would take more than twenty years to deliver benefits than would other alternatives studied Instead, the Corps recommended major improvements to fish passage at the dams. The RPA includes numerous dam improvements consistent with this recommendation. Since 2000, there have been significant improvements that should translate to increases in survival across the salmon life cycle, including:

Also, under the ESA, the action is necessarily limited to operating the FCRPS consistently with authorized project purposes. Currently, none of the responsible Federal agencies has Congressional authority to significantly alter the Snake River dams. Therefore, absent new Congressional action, it is not possible that such an action would be reasonably certain to occur or otherwise meet ESA standards for inclusion in the FCRPS Biological Opinion.

Adverse environmental effects from dam breaching are also an important consideration. Water quality for all downstream species would be negatively impacted by movement of sediment following dam breaching. An estimated 100-150 million cubic yards of impounded sediments have accumulated upstream of the Snake River dams. The Corps' Lower Snake River Feasibility Study estimated approximately one-half of this material would migrate downstream and end up in the McNary reservoir. The biological implications of the sediment movement are uncertain but would likely result in high turbidity loads for 5-7 years following breaching (Corps 2002).

In addition to water quality and other effects (Corps 2002), these include the air quality implications of replacement power resources (NPCC 2007), moving backwards rather than forwards in regional goals to decrease carbon emissions (NPCC 2007), and loss of ability of integrate other renewable resources into the regional power grid (BPA 2007). Considering the potential for climate change, these environmental considerations also argue against pursuing Snake River dam breaching.

The 2008 FCRPS Biological Opinion supports a comprehensive, All-H strategy including continued fish passage improvements at the Snake River dams such as surface collection and bypass improvements, as well as offsite actions including habitat and hatchery improvements, to meet the needs for listed fish. This approach benefits not only Snake River fish, but also Upper Columbia and Mid-Columbia salmon and steelhead. For further detail please see Issue Summary: "Why the 2008 FCRPS Biological Opinion Does Not Include Removal of the Four Lower Snake River Dams."

NOAA Fisheries
Issue 20: Comments Calling for Breaching Dams on Lower Snake River
FCRPS Biological Opinion, May 5, 2008

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