Review of the U.S. Army Corps of Engineers Capital Construction Program,  Part IIIA "Adult Passage"

January 26, 1999  |  document ISAB 99-2

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Background

The Council has been directed by the Congress, in the Conference Report accompanying the Energy and Water Development Appropriations Act for the Fiscal Year 1998, to review "the major fish mitigation capital construction activities proposed for implementation at the Federal dams in the Columbia River Basin." The Council was directed to conduct this review by June 30, 1998, with the assistance of the Independent Scientific Advisory Board (ISAB).

We previously submitted reports, ISAB 98-4, covering questions from the Council about the ecosystem context for mainstem fish passage measures as well as the questions about the specific measures for John Day and Bonneville dams, and ISAB 98-7 and 98-8, respectively, covering the surface collection and gas saturation questions.

This report (ISAB 99-2) addresses issues concerning adult passage as part of our review of the Corps’ capital construction program. With respect to specific adult passage measures identified for improvement, the ISAB had information from the "Technical Background Paper for Review of the Corps Capital Construction Program" addressed to the System Coordination Team (SCT) from Council staff on February 9, 1998. We also had the Corps of Engineers Work Plans for 1997 and 1998, which identified measures for improvement of adult passage that the Corps proposed to undertake.

We also were aided in our review of adult fish passage improvements through a briefing by Dr. Ted Bjornn (University of Idaho) and Lowell Stuehrenberg (NMFS) on November 16, 1998, that was attended by Corps representatives. In addition, we had Council Staff's Technical background paper (NPPC-document # 97-18) and reports on radio-tracking of Snake River fall chinook by Glen Mendel of the Washington Department of Fish and Wildlife (memo of November 16, 1998 to the ISAB) and the conversion factors on dam counts from Mike Matylewich (Columbia River Intertribal Fish Commission). The latter two reports were solicited by the ISAB. We also greatly appreciate the assistance of Larry Basham of the Fish Passage Center in gaining an understanding of the problems encountered in monitoring of numbers of adults passing the dams.

Questions to the ISAB

The immediate questions before the ISAB with respect to adult passage are:

• Are the proposed measures for improvement of adult passage at the Corps projects necessary and desirable; and
• Do they represent a complete list of necessary and desirable measures to assist in accomplishing the region’s goals for restoration and recovery?

Recommendations

The ISAB’s technical evaluation concludes that the subject of adult passage at Columbia River dams has not been adequately dealt with. There appears to be a widely held assumption in the region that problems of adult passage have, for the most part been solved. The Corps of Engineers' Capital Construction budget for adult passage addresses what we consider to be minor fixes and adjustments of existing systems. These planned site-specific measures are supportable, but probably are not sufficient to ensure that adult spawning migrations are unimpeded and completed with minimal mortality induced by passage. Additional evaluation, field research, and (probably) capital projects will be needed before the problems of adult passage may be considered to have been adequately addressed.

Question 1. Are the proposed measures for improvement of adult passage at the Corps projects necessary and desirable?

Answer. Yes. While the proposed measures are all relatively small changes and improvements to existing adult fish passage systems, this is not to minimize their importance. Each appears to offer an improvement in the context of the specific dam site and fishway configuration in response to problems that have been observed. Many address what might be considered operations and maintenance issues, or provide back-up systems to reduce the possibility of interruption of fishway operation. The list was arrived at with input from the System Configuration Team (SCT).

Recommendation. Implement the sixteen capital construction measures proposed by the Corps to achieve improved adult passage at individual projects.

While the sixteen proposed projects are necessary and desirable, they do not attempt to address larger-scale problems and uncertainties for upstream migrating adult salmon and steelhead.

Question 2. Do the proposed measures for improvement of adult passage at the Corps projects represent a complete list of necessary and desirable measures?

Answer. Probably not. At any specific dam site or fishway, there are undoubtedly additional measures that could be adopted to maintain or marginally improve fish passage performance. On a broader scale, major or dramatic changes may be desirable if better data and further analysis shows that losses of adults associated with passage is a larger cause of poor salmon production than has previously been recognized. Our review shows that the questions associated with adult passage are not well resolved, and better information is needed than we now have available to us.

Problems with adult passage deserve more attention than they have received. Many questions remain about the effects of delay or extra energy expenditure en route upstream on the ultimate ability of adults to spawn successfully. We are aware of no research program that is designed to satisfactorily answer these questions. Uncertainties about adult passage must be viewed in a larger context than simply a project-by-project review of desirable modifications of ladders and their associated facilities at mainstem and Snake River dams. For example, are the present measures successful in allowing an adequate number of adult salmon and steelhead to reach their spawning grounds in a physical condition required for successful spawning?

Counts of adult fish in the ladders are the primary source of information on the numbers of fish that are successful in passing the dams. These numbers are critically important for monitoring the effectiveness of passage measures for adults, for evaluating effectiveness of restoration and recovery measures, and for setting and maintaining appropriate spawning escapement goals. Our review of those counts led to a concern that these numbers probably are not sufficiently reliable for the purposes for which they are being used.

Recommendations.

1. More emphasis should be placed on monitoring and evaluation of adult salmon numbers by the Corps, the Council, NMFS and the harvest management entities.
2. Include an annual operating project to determine the accuracy and precision of the counts of adult salmon passing the dams. Install PIT tag detectors for adults at each project to provide data for estimates of survival in upstream passage, and to adjust the counts.
3. Critically evaluate sources of error in estimation of escapement to spawning grounds and hatcheries.
4. Support research to record temperatures experienced by adults during upstream migration.
5. Consider reestablishing a bioengineering test facility for adult fish passage in the Columbia River basin where engineering designs for passage improvement can be tested in full-scale with adult salmon. Fish behavior is a critical element in fish passage design and it cannot be ignored. Current investigations by the Corps’ using scale-models at their Vicksburg, Mississippi facility do not appear to incorporate fish behavior to this degree.

Description of the Report

We address two principal issues in this report. The first relates to the Corps' capital construction program as described for specific projects in the Corps' Work Plans for 1997 and 1998 and the Council staff's Background Paper. The second relates to a larger perspective, the monitoring of adult passage on a systemwide basis through the facilities at the Corps projects. The report is accordingly divided into two sections, Section 1: The Corps of Engineers Capital Construction Program for 1997 and 1998, and Section 2: Monitoring and Evaluation of Adult Passage in the Columbia and Snake Rivers. The second section addresses the issue of larger problems in adult passage that may exist. These sections are preceded by a background section that describes basic ecological factors relevant to adult fish passage at the Columbia and Snake river mainstem projects.

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