Damming a river may bring electric power, but it often comes at the price of high-quality food fisheries, experts say. When dams are proposed for power, flood control or irrigation, the often devastating impacts on fisheries in rivers and lakes are ignored or discounted.

This report by the UN Environment Programme (UNEP) and the World Fish Centre warns that despite over 40 years of steady production globally, rapid environmental changes are occurring which challenge the viability of future fish stocks and a range of internationally- agreed development targets including the Millennium Development Goals.

The report is available online at http://www.unep.org/pdf/Blue_Harvest.pdf

This Technical Guidance Note was primarily prepared as a contribution to the World Bank economic and sector work—mainstreaming environmental flow requirements into water resources investments and policy reforms jointly supported by the Environment Department and the Energy, Transport and Water Department. The technical note also forms a contribution to the Bank’s hydropower investments. The main objective of the note is to serve as a guidance document as opposed to a technical manual. It has been developed to assist World Bank staff and their clients to identify ways to better incorporate the benefits associated with environmental flow protection into hydropower dam projects.Most of the material in this note will be equally applicable to hydropower dams with either multiple objectives or a single objective, but the integration of environmental flow protection into projects with multiple objectives presents some special challenges. In addition, many issues covered in this note will be applicable to other types of water infrastructure projects.

Hydraulic potential stored in water reservoirs can be converted to useful power through the work of turbomachinery. However, nations around the world have large numbers of existing dams with hydropower potential left unused. These dams were mostly built during the latter half of the 20th century. At that time, thermal electric energy supply, generated with abundant cheap fossil fuels made small scale hydropower generation less attractive. Another reason for such low utilization of these clean renewable energy resources is the significant capital cost of equipment and hydropower plant construction. This made small hydropower development economically noncompetitive. With the rapid depletion of fossil fuel and the increased environmental and global warming concerns, it becomes highly desirable to harness clean renewable energy sources.

To retrofit a conventional hydroturbine onto an existing dam brings out several major issues. They include structural integrity and safety of the dam, and the cost of construction and complex engineering tasks involved in properly integrating a powerhouse into the existing structure. These issues have seriously impeded the progress in developing these hydroelectric potentials. In addition, available data indicates that existing hydroturbine technology has some undesirable ecological impacts by causing injury and mortality to passing fish and deterioration of downstream environmental condition resulting from undesirable levels of dissolved gas.

In this paper the authors will first briefly summarize current hydropower development needs and challenges, and then describe a new approach to effectively meeting these challenges by using an innovative hydroturbine system. The new hydroturbine system consists of four key design innovations: 1) an updraft flow arrangement, 2) a vertical pressure-balanced turbine flow control valve in place of the conventional wicket gates, 3) a divergent runner flow chamber serving the function of the draft tube, and 4) exit flow at the free surface in the tailwater terrace.

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.

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.

Regulation and fragmentation by dams belong to the most widespread deliberate impacts of humans on the world