This report presents a review of economic studies for the United States and relates them to predicted impacts of climate change. The summary findings are organized by region and identify the key sectors likely affected by climate change, the main impacts to be expected, as well as estimates of costs. The report builds on the 2000 Global Change Research Program National Assessment, using additional regional and local studies, as well as new calculations derived from federal, state and industry data sources. From this review and quantification, five key lessons emerge:

1. Economic impacts of climate change will occurthroughout the country
2. Economic impacts will be unevenly distributedacross regions and within the economy andsociety.
3. Negative climate impacts will outweighbenefits for most sectors that provide essentialgoods and services to society.
4. Climate change impacts will place immensestrains on public sector budgets.
5. Secondary effects of climate impacts caninclude higher prices, reduced income and joblosses.

A report submitted to the House Resources Committee, Subcommittee on Fisheries, Wildlife, and Oceans by the Office of Technology Assessment.

The focus of this report is technologies for fish passage around hydropower generation facilities and protection against entrainment and turbine mortality.Emphasis is given to Federal Energy Regulatory Commission (FERC)-licensed hydropower projects where fish protection is a subject of controversy and congressional interest due to the Federal Power Act (FPA) and the Electric Consumers Protection Act (ECPA). Thus institutional issues related to FERC-relicensing are also discussed. (Major points of controversy are highlighted in box 1-1.) Federal hydropower projects,especially in the Columbia River Basin, and irrigation water diversions in the Pacific Northwest and California are included to the extent that they provide information on fish passage technologies(see table 1-1). Many of the technologies discussed are applicable to other types of dams and water diversions. In fact, there are many more obstructions to fish passage that are not covered by FERC-licensing requirements, than are(approximately 76,000 dams versus 1,825 FERC-licensed facilities) (70).

Threats to imperiled freshwater fauna in the U.S. were assessed through an experts survey addressing anthropogenic stressors and their sources. Specifically, causes of historic declines and current limits to recovery were identified for 135 imperiled freshwater species of fishes, crayfishes, dragonflies and damselflies, mussels, and amphibians. The survey was designed to identify threats with sufficient specificity to inform resource managers and regulators faced with translating information about predominant biological threats into specific, responsive actions. The findings point to altered sediment loads and nutrient inputs from agricultural nonpoint pollution; interference from exotic species; and altered hydrologic regimes associated with impoundment operations as the three leading threats nationwide, accompanied by many lesser but still significant threats. Variations in threats among regions and among taxa were also evident. Eastern species are most commonly affected by altered sediment loads from agricultural activities, whereas exotic species, habitat removal/damage, and altered hydrologic regimes predominate in the West. Altered sediment loading from agricultural activities and exotic species are dominant problems for both eastern mussels and fishes. However, eastern fishes also appear to be suffering from municipal nonpoint pollution (nutrients and sediments), whereas eastern mussels appear to be more severely affected by altered nutrient impacts from hydroelectric impoundments and agricultural runoff. Our findings suggest that control of nonpoint source pollution associated with agriculture activities should be a very high priority for agricultural producers and governmental support programs. Additonally, the large number of hydropower dams in the U.S. subject to federal re-licensing in coming years suggests a significant opportunity to restore natural hydrologic regimes in the affected rivers.

Many river restoration projects are focusing on restoring environmental flow regimes to improve ecosystem health in rivers that have been developed for water supply, hydropower generation, flood control, navigation, and other purposes. In efforts to prevent future ecological damage, water supply planners in some parts of the world are beginning to address the water needs of river ecosystems proactively by reserving some portion of river flows for ecosystem support. These restorative and protective actions require development of scientifically credible estimates of environmental flow needs. This paper describes an adaptive, inter-disciplinary, science-based process for developing environmental flow recommendations. It has been designed for use in a variety of water management activities, including flow restoration projects, and can be tailored according to available time and resources for determining environmental flow needs. The five-step process includes: (1) an orientation meeting; (2) a literature review and summary of existing knowledge about flow-dependent biota and ecological processes of concern; (3) a workshop to develop ecological objectives and initial flow recommendations, and identify key information gaps; (4) implementation of the flow recommendations on a trial basis to test hypotheses and reduce uncertainties; and (5) monitoring system response and conducting further research as warranted. A range of recommended flows are developed for the low flows in each month, high flow pulses throughout the year, and floods with targeted inter-annual frequencies. We describe an application of this process to the Savannah River, in which the resultant flow recommendations were incorporated into a comprehensive river basin planning process conducted by the Corps of Engineers, and used to initiate the adaptive management of Thurmond Dam.

The Georgia State Soil and Water Conservation Commission (Commission), in partnership with the Natural Resource Conservation Service (NRCS) and the Georgia Environmental Protect Division (EPD), has begun to evaluate the flood control dams, designed and constructed under federal laws PL 544 and PL 566, to determine which structures can be modified to serve as water supply reservoirs.

The results of the analyses presented herein are based upon United States Geological Survey (USGS) quadrangle maps and, therefore, should be utilized for planning purposes only. If any of the subject projects are identified as having a possibility of progressing past this analysis, additional studies will be required. These studies will include but not be limited to detailed environmental evaluations, detailed yield analyses, preliminary engineering design, and detailed cost estimating. These additional studies will be required prior to beginning detailed design work and/or land acquisition. The level of study presented herein shall be considered as a screening tool to evaluate the one project strengths and weaknesses relative to other projects. Until further studies are performed, actual yield and environmental factors associated with each project can not be readily determined.

The potential effects of climate change on the hydrology and water resources of the Columbia River Basin (CRB) were evaluated using simulations from the U.S. Department of Energy and National Center for Atmospheric Research Parallel Climate Model (DOE/NCAR PCM).

This study focuses on three climate projections for the 21st century based on a ‘business as usual' (BAU) global emissions scenario, evaluated with respect to a control climate scenario based on static 1995 emissions. Time-varying monthly PCM temperature and precipitation changes werestatistically downscaled and temporally disaggregated to produce daily forcings that drove a macroscale hydrologic simulation model of the Columbia River basin at 1/4-degree spatial resolution.

This analysis uses the Indicators of Hydrologic Alteration tool in concert with basic hydrological statistical analyses to assess the new flow regime dictated for the High Falls Gorge bypassed river reach, on the Saranac River.

Hydrologic data are linked with known relationships between flow variables and ecological responses. General ecological effects of the new flow regime are predicted based on these relationships. Proposed pulse flows are discussed in this hydrological context. An enhanced flow regime is suggested based on the findings of these analyses.

Note: While this analysis was conducted on a specific FERC project, this work has implications on many other projects where IHA could add value, or where the delphi habitat assessment methodology is proposed.

This report discusses "Active River Area" and the benefits it provides along with ways to protect the area to achieve river conservation.

Available online at

http://www.nature.org/initiatives/freshwater/files/active_river_area.pdf 

This report evaluates the flood control dams, designed and constructed under federal laws PL 544 and PL 566, to determine which structures can be modified to serve as watersupply reservoirs, i.e. conversion of ag dams to water supply dams.

    Water-level declines in the river have substantially changed long-term hydrologic conditions in more than 200 miles of off-channel floodplain sloughs, streams, and lakes and in most of the 82,200 acres of floodplain forests in the non-tidal reach of the Apalachicola River.

Decreases in duration of floodplain inundation at low discharges were large in the upstream-most 10 miles of the river (20-45 percent) and throughout most of the remaining 75 miles of the non-tidal reach (10-25 percent). As a consequence of this decreased inundation, the quantity and quality of floodplain habitats for fish, mussels, and other aquatic organisms have declined, and wetland forests of the floodplain are changing in response to drier conditions. Water-level decline caused by channel change is probably the most serious anthropogenic impact that has occurred so far in the Apalachicola River and floodplain. This decline has been exacerbated by long-term reductions in spring and summer flow, especially during drought periods. Although no trends in total annual flow volumes were detected, long-term decreases in discharge for April, May, July, and August were apparent, and water-level declines during drought conditions resulting from decreased discharge in those 4 months were similar in magnitude to the water-level declines caused by channel changes. The observed changes in seasonal discharge are probably caused by a combination of natural climatic changes and anthropogenic activities in the Apalachicola-Chattahoochee-Flint River Basin.

Continued research is needed for geomorphic studies to assist in the design of future floodplain restoration efforts and for hydrologic studies to monitor changes in the future flow regime of the Apalachicola River as water management and land use in this large tri-state basin continue to change.

The report is available at http://pubs.usgs.gov/sir/2006/5173/