Water

Dams and Development E-Paper Contents

p. 47 of 74 BACK | NEXT Home Page of Dams and Development Foreword I. Why an e-paper on dams and development? II. Assessing options III. Participatory processes IV. Social impacts V. Environmental impacts VI. Benefit distribution VII. Dam safety and sustainability Dam safety Operation in times of flood Reservoir quality Managing sedimentation VIII. Existing projects IX. Improving governance X. What other organizations say XI. ADB, Dams, and Development XII. References Contact Us

Monitoring and maintaining reservoir water quality

Extensive information and case studies are available on the various parameters and issues related to water quality in reservoirs and downstream river reaches. These are summarized in the following publications prepared by WHO, UNESCO and UNEP:

Water quality assessments: A guide to the use of biota, sediments and water in environmental monitoring, 2nd ed. The guide 'gives comprehensive and practical advice on designing and setting up monitoring programmes to obtain valid data for water quality assessment in all types of freshwater bodies'.

Water quality monitoring: A practical guide to the design and implementation of freshwater quality studies and monitoring programmes This work 'which will be particularly relevant for field use in developing countries, provides:

• a general protocol for the design and implementation of a monitoring programme in surface and groundwater;
• details of sampling and analytical methods;
• guidance on data analysis and presentation.

An overview is of water quality is also provided by the International Commission on Large Dams in Bulletin No. 128: Management of reservoir water quality - Introduction and recommendations published in 2004 and available from the ICOLD publications webpage.

This is supported by ICOLD Bulletin No. 127, Remote sensing for reservoir water quality management - Examples of initiatives.

Examples of strategies implemented by basin managers to overcome quality problems include:

Improving Water Quality Below TVA Hydropower Dams with a focus on boosting dissolved oxygen and reducing occurrence of dry riverbeds downstream.

Murray Darling Basin Commission Basin Salinity Management Strategy with objectives of :

• maintaining the water quality of the shared water resources of the Murray and Darling Rivers;
• controlling the rise in salt loads in all tributary rivers of the Murray-Darling Basin;
• controlling land degradation and protecting important terrestrial ecosystems, productive farm land, cultural heritage and built infrastructure; and
• maximise net benefits from salinity control across the Basin.

Murray Darling Basin Commission Algal Management Strategy with four key objectives:

• reduce nutrient concentrations in the streams and storages in the Basin;
• improve stream-flow regimes and flow management;
• increase the community's awareness of the blue-green algal problem; and
• obtain better information and scientific knowledge of blue-green algae.

Operational Alternatives for Total Dissolved Gas Management at Grand Coulee Dam

Grand Coulee dam was constructed by the Bureau of Reclamation (Reclamation) in the 1930's before much was known about total dissolved gas and the effects it has on the environment. Releases during high flows were found to cause high levels of dissolved gas that were harmful to fish and exceeded water quality standards under the Clean Water Act. Of particular concern were effects upon anadromous species covered under the Endangered Species Act.

Reclamation's Technical Service Center studied releases at Grand Coulee Dam on the Columbia River in order to determine operational methods which would reduce the amount of total dissolved gasses associated with releases at the dam. Studies were conducted of releases over the spill way, through the outlet tubes (upper and lower levels) and combinations of these. The studies found that different releases under certain conditions resulted in lower dissolved gas levels. As a result of the findings, Reclamation developed standard procedures for water releases that have lower levels of gas.

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