This paper reports the results of studying soil hydraulic structures (SHS) of the CC1 class of consequences on small rivers. The representativeness of the results for the domestic and world practice of further operation of such structures is ensured by the typical technical and technological approaches to the construction, materials, and conditions of their work. Dams are built of soil materials and operated over significant time periods while their standard service life has been exhausted, which increases the environmental and technical danger of their further operation. Visual surveys were conducted and the technical condition was instrumentally diagnosed by the geophysical method of the earth's natural pulsed electromagnetic field (ENPEMF); observational data were mathematically treated. The possibility of arranging areas of increased water filtration through the SHS body was substantiated, as well as watering, loosening, and suffusion; potentially dangerous zones prone to landslides, cracks, and collapse were determined. The probability of risk of an accident on dams was estimated at their cascading arrangement as a result of filtration deformations of the body and the base of the structure. Under current operating conditions, the possibility of letting the normative and excess (forced) water volumes through water discharge facilities due to precipitation or a breakthrough of the structure located upstream was estimated. The proposed approach makes it possible to manage the cascade of hydraulic structures at different stages of operation: planned, operational decision-making, forecasting. This allows diagnostic examinations to be performed in order to identify structures that require priority in raising funds for repair and restoration work or demolition (dismantling)

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Reports on the environmental impact assessment of planned activities aimed at restoring the hydrological regime and sanitation of rivers do not always pay attention to in-depth analysis of the physicochemical composition of bottom sediments. The silt deposits have proven to be a good ameliorant for agricultural lands, provided they are of satisfactory quality. Bottom sediments, especially their fine alluvial fraction, accumulate various compounds and trace elements, including heavy metals. Analysis of the content of iron Fe, manganese Mn, cobalt Co, chromium Cr and determination of the integrated level of contamination of bottom sediments did not reveal their toxic contamination in the area of the village Kleshnivka and the village Petrykivka. Determination of "geoaccumulation indices" by G.M. Mueller allowed to classify the sediments of the Chaplinka River as unpolluted, and the man-caused load on the hydroecosystem as low. In compliance with the recommendations on the content of Mn grades in the soil cover of the obtained fifth Igeoclass, which provides heavy pollution and significant man-caused load on the hydroecosystem. To characterize the processes occurring in the hydroecosystem of the Chaplynka River, the bottom accumulation coefficient was calculated. The assessment of the ecological status of hydroecosystems revealed an overwhelming ecological emergency. There is a significant threat of deposits of iron Fe, manganese Mn in bottom sediments. Despite the low risk of contamination of bottom sediments with chromium Cr, the risk will increase due to the rather variable chemical composition of surface waters, and hence the possibility of an ecological crisis for the hydroecosystem. The sanitary condition of a small river could be improved by restoring its hydrological regime. The decrease in the efficiency of dredging works is related to the regulation of the regulation of the riverbed. In the vast majority of cases, hydraulic structures are not provided for or do not correspond to the current level regime of watercourses. After clearing the river bed, there is a danger of their secondary silting, due to the abandonment of part of the temporary dumps on the banks within the water protection zones without fixing.