Floodplains are among the most productive areas of rivers for salmonid fishes. An important process influencing floodplain productivity is hyporheic flow that creates thermal regimes highly favorable for spawning, incubation, and rearing. The proposed work will identify hyporheic areas in subbasins, predict their effects on stream temperatures, and assess the importance of hyporheic flows fish productivity in floodplain habitats. The work addresses a critical need for habitat restoration in large rivers and is the only work of its kind in the Columbia River Basin. The work will help identify areas of subbasins where restoration would likely yield large benefits for salmonids.

The sponsors list an expected benefit as "classification all major floodplains in the Columbia River Basin." While this benefit may accrue in the future, the funded work should be restricted to the eight key test basins.

Technical and scientific background: Parts of the technical background are quite good. The graphics describing large-scale hyporheic analyses are excellent and would be a valuable addition to any subbasin analysis and plan. The background also makes a strong connection between hyporheic flow paths and stream cooling, which will certainly influence where some of the most productive segments of the drainage system for salmonids will be located.

There are also some questions that deserved greater attention. The actual influence of hyporheic flow (apart from temperature moderation) could have been more fully explored. Hyporheic zones influence nutrient dynamics, which in turn will affect stream productivity; however, nutrients are not really addressed. The ways in which anthropogenic disturbances have altered hyporheic development (and how these disturbances can be undone) also need to be addressed -- otherwise, how will the information generated by this project be effectively used? Are there some changes (e.g., severe downcutting) that have altered the hyporheos to the point that natural conditions can't be restored for decades or more? Can such changes be detected by the proposed analytical methods?

Although a minor point, some of the figures appeared to have been misplaced in the text (several pages from where they were referenced) and legends were missing, e.g., Fig. 2.

Rationale and significance to subbasin plans and regional programs: Developing a cost-effective, accessible technique for identifying areas with high hyporheic potential would clearly benefit subbasin plans. The selection of study areas would seem to be most applicable to Mid-Columbia and Columbia Cascade provinces. The stated goal of classifying "all major floodplains in the Columbia River Basin" would seem to be a bit optimistic without a broader spectrum of study areas; e.g., none of the sites were located in tributaries of the Lower Columbia or Willamette River. However, for the area in which the study takes place, the project would likely provide valuable information.

Relationships to other projects: The proposal references many linkages but is not entirely clear about how these linkages would occur. For example, the statement "Outcomes of this project will be directly coordinated with several projects in the Umatilla River Basin; specifically, Quantitative Assessment of Migrating Upstream Lamprey, Project #9402600, Umatilla Habitat Project, #8710002, Walla Walla Basin Habitat Enhancement, #9604601, North Fork John Day River Basin Anadromous Fish Habitat Enhancement, #200003100, Walla Walla Basin Natural Production Monitoring and Evaluation Project, #200003900 and Characterize Genetic Differences and Distribution of Freshwater Mussels, #200203700" simply states the relationship but does not describe how the integration would be achieved; i.e., what products or information will be exchanged.

Nearly all the other projects are located in the Mid-Columbia and there is no mention of linkages to related projects in other parts of the basin. This would not be a problem except one of the project's objectives is to classify hyporheic potential throughout the Columbia River Basin, and referencing floodplain work in other areas would be helpful.

Objectives: The four objectives were clearly defined, although without much specificity with regard to products or timelines. The objectives also were not explicitly tied to elements of the Fish and Wildlife Program or to individual subbasin plans. The first three objectives describe the methods to be used for classifying floodplains with regard to hyporheic potential. These objectives were very specific.

The fourth objective (Relating the importance of hyporheic flows to fish use) was concerned primarily with relating areas with well-developed hyporheic flowpaths to spawner abundance. While this is worthwhile, many of the focal species may not be primarily floodplain spawners but instead may spawn in smaller montane streams. Juvenile salmonid abundance would certainly be worth associating with floodplains with well-developed hyporheic systems. Perhaps this component could be added to the project.

Objective 4 also states that geomorphically and thermally diverse stream segments will be related to salmon abundance, species diversity, and life history diversity. While this is also a worthy goal, the proposal does not provide a clear indication of how spatially defined existing biological data are, relative to the stream segments in question.

Tasks (work elements) and methods: For the geographic analyses, the proposal describes the methods very completely. For the biological parameters, not enough information is presented to adequately judge the methods. The investigators are experienced with the methodologies required for this work and have successfully applied the approach in the Umatilla basin.

Monitoring and evaluation: There are not very many places in the proposal where ground-truthing model predictions are mentioned. While this is probably not a problem in the Umatilla subbasin where CTUIR maintains a very complete database, it could be a real problem for areas of the Columbia River Basin that do not include study sites.

Facilities, equipment, and personnel: Facilities are well equipped for this work and the sponsors are well qualified with demonstrated peer-reviewed publication records.

Information transfer: The proposal mentions only online data storage and retrieval. There is no mention of reports, publications, or scientific presentations. The sponsors have a good record of peer-reviewed publications and surely results of this work will be published in scientific journals.

Benefits to focal and non-focal species: This project has the potential to be of great benefit to focal species if areas with high hyporheic potential can be accurately identified and either protected or restored. The effects of anthropogenic alterations such as diking, shallow water wells, stream downcutting, and removal of riparian vegetation are inadequately discussed. Protecting and/or restoring hyporheic potential should benefit non-focal species too.