Hydropower plants affect the distribution and composition of sediments. The main aim of this study was to analyze the spatial distribution of sediment pollution in the vicinity of a small hydropower plant. The grain composition of the sediments, the content of heavy metals (Cu, Ni, Cr, Zn, Pb, and Cd) and select physicochemical properties (pH, electrolytic conductivity) were tested at 14 points upstream and downstream of the hydropower plant on the Ślęza River in Poland, as well as at reference point. The interactions between the tested parameters were also verified. The results of the conducted analysis show that hydropower plants significantly affect the composition and properties of sediments. Large amounts of sediment are deposited on damming weirs, accumulating heavy metals and other substances. The differences in the concentrations of elements were significant, and Cu, Ni, Cr, Zn and Pb were 8.74, 9.53, 3.63, 8.26 and 6.33 times higher, respectively, than the median value at points upstream of the hydropower plant than downstream. It was shown that the tested parameters of the sediments interact with each other and are correlated; heavy metals showed a synergistic effect, while other parameters configurations showed an antagonistic effect. The higher content of heavy metals upstream of the hydropower plant resulted from the presence of finer sediment—classified as silt—in this section. Downstream of the hydropower plant, there were mainly sands, which showed a lower ability to absorb substances. This work contributes to improving the rational management of the worldwide issue of sediments within dams located in river valleys. Moreover, it is in line with the 2030 Sustainable Development Goals adopted by the United Nations, particularly in the fields of clean water and sanitation, clean and available energy, and responsible consumption and production.

The objectives of the article are: to assess spatio-temporal evolution of eutrophication and water quality of the Turawa dam reservoir, located in south-western Poland on the Mała Panew River; to identify location and relationship between potential sources of physicochemical pollution related to the progressing process of eutrophication; and to determine trophic status and water quality indices of the selected research object. The analysis (Mann–Whitney U test, PCA, HCA, Spearman correlation matrix) showed a high susceptibility of the reservoir to eutrophication processes, especially due to the influence of dangerous loads of compounds emerging from areas with high tourist intensity and pollutants flowing from the Mała Panew River. The parameters deteriorating the ecological status were TP, DO, BOD5, and COD. Considering the cumulative results of water quality indices for the period 1998–2020, the average water quality was in classes II or III. A noticeable deterioration appeared in water quality for the years 2016–2020, which proves the progressing eutrophication in the Turawa reservoir. In 1998–2020, the reservoir was classified as eutrophic or mesoeutrophic based on the calculated three trophic status indices. This article would help in developing a strategy for dealing with water blooms, a reliable system for monitoring pressures causing eutrophication, and optimal technologies for the reconstruction of multifunctional reservoirs.

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