Effectiveness of Water Release as Mitigation for Hydroelectric Impacts to Fish

• Published in: Journal of energy engineering 1995-08, Vol.121 (2), p.81-88
• Main Authors: Lewis, Adam F, Clyde Mitchell, A
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Conservation, protection and management of environment and wildlife; Environmental degradation: ecosystems survey and restoration; Fundamental and applied biological sciences. Psychology; TECHNICAL PAPERS
• ISSN: 0733-9402; 1943-7897
• DOI: 10.1061/(ASCE)0733-9402(1995)121:2(81)

Utility companies release water to mitigate the effects of hydroelectric projects on fish habitats. Utility companies, government agencies, and research communities in Canada, the United States, Europe, New Zealand, and Australia were surveyed as part of a Canadian Electrical Association study to evaluate the effectiveness of water release as a mitigation. Respondents identified only 28 projects in which water was released specifically to protect fish habitats. Fewer than half of these projects (12) were judged as being effective. Six case histories with preimpact assessment and postimpact monitoring were reviewed. In four cases fish habitat or fish populations or both were maintained; in two cases they were not. The effectiveness of water release differed among rivers and fish species, and was greatest when designed to meet the habitat requirements of each life-history stage. A review of the literature did not support the theory that a particular fraction of the mean annual flow provides the best fish habitat. Although smaller changes in the flow regime had smaller effects, increasing minimum flows above those historically observed did not necessarily increase fish production.