Small hydropower plants’ impacts in urban areas: Assessment of water quality from an environmental, social, and economic perspective

Water is the basis for the life of organisms and is used for various purposes, especially in agriculture, industry, municipal, and energy production. Assessing water quality in terms of its various uses is not without significance. This study investigates the water quality within two small hydropower plants in an urban area from natural, social and economic perspectives. Wroclaw I and Wroclaw II hydropower plants on the Odra River in Poland were selected as case studies. This study presents the results of four-year research (2017-2020) for points located upstream and downstream of the intake. The following elements were assessed: physicochemical status, trophic status, assessment of fish living conditions, and water quality indices. The results show that hydropower plants improved the average physicochemical status of BOD
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(by 6.19% comparing the results downstream and upstream of the hydropower plant), dissolved oxygen (3.S5%), PO
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- P (3.31%), and electrical conductivity (0.52%), however, they worsened in the case of the pH (by 2.63%) and NO
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-N (by 1.S3%). Water near the study cases is classified as mesotrophic or eutrophic. The conditions for the existence of salmonids and cyprinids were not met due to the increased concentrations of NO
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and BOD
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values. In the case of salmonids, also due to the temperature and dissolved oxygen concentration. The water quality indices differed and indicated the quality from poor to good, depending on the classification. This study provides important insights for policymakers regarding the impacts of small hydropower plants on water quality in urban areas.