Specifics of the watercourses research in Ukrainian Carpathian Mountains is in developing and using the most appropriate research methods. This will objectively and comprehensively assess the quality situation of water objects. Were reviewed and analyzed different methodological aspects of water quality researching. The use of bioindication methods that are an integral and necessary part of researching the current situations and changes in water (river) ecosystems of mountain regions is

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... iated. The methods were used in long-term and comprehensive research of river Prut and the article represents a summary of the results. Argumentation of using this bioindication method in an integrated research of mountain rivers of the Ukrainian Carpathian Mountains is given. Key words: bioindication, monitoring, water quality, ecosystems, research methods, indices of quality.