The environmental assessment of the surface water quality of the Western Bug River has been made using the system of classification quality of land surface water of Ukraine in accordance with the approved methodology, which allows comparing water quality of separate areas of water objects of different regions. The calculation of the environmental assessment of water quality has been carried according to three blocks: block of salt composition, block of trophic and saprobic (ecological and sanitary) indicators and block of indicators of content of specific toxic substances. The results are presented in the form of a combined environmental assessment, based on the final conclusions of the three blocks and consists in calculating the integral ecological index. Comprehensive studies of changes in the water quality of the Western Bug River have been conducted within the territory of Ukraine for a long-term period. The water quality of the river on the final values of the integral indicators of the ecological condition corresponded mainly to 4nd category of the 3rd class – the water is “satisfactory” by condition and “little polluted” by degree of purity (except for points of observation that located within the Volyn region, where the water quality corresponded to 3rd category and the 2nd class. It is “good” by condition and “fairly clean” by the degree of purity). Visualization and part of the analysis are performed using GIS technologies in the software of the ArcGIS 10.3.

Monitoring of surface waters within the transboundary section of the Western Bug River showed, that during 2014-2018, a significant excess of the maximum permissible concentration (MPC) was observed for some substances for fish ponds. As a result of this, the water in the river for these substances was rated as "dirty" in terms of purity and corresponded to water quality class IV, namely: phosphorus was observed to exceed the MPC at the observation point Ambukіv village in 2015 (9.7 times), for manganesean excess of the MPC at the observation point Ambukіv village in 2018 (9.7 times) and in point Zabuzhzhia village in 2014 (7.9 times), 2015 (8.0 times), 2017 (7.1 times), 2018 (8.3 times); for the total iron -the exceeding of MPC at the observation point Ambukіv village in 2016 (5.95 times) and 2017 (6.13 times); at the observation point Ustilug town in 2016 (5.23 times); in the observation point Zabuzhzhia village in 2016 (9.44 times) and 2017 (5.27 times). The assessment of the surface waters based on the determination of the pollution factor showed that during the study period their quality did not deteriorate but did not meet the norms. In general, surface waters of the river correspond to the second class of quality and are characterized as "poorly polluted" waters by the level of pollution.

The quality of surface waters of small rivers of the Ukrainian regions of right-bank Polissia, belonging to the basin of the river Pripyat, was estimated. The study was conducted via systematic observations based on the ecological classification of surface water quality of land and estuaries of Ukraine, which includes a set of hydrophysical, hydrochemical, hydrobiological and other indicators, which were grouped into three blocks of indicators: salt composition of water; tropho-saprobiological (ecologicalsanitary) block; specific substances of toxic action. The integrated (ecological) index was determined, by which the class and category of surface water quality were established. The results of observations on the quality of surface waters of the rivers of the Ukrainian regions of right-bank Polissia indicate their satisfactory condition. Surface waters, on average, correspond to the II class of water quality, and the worst - to the III class. Water protection measures have been proposed to improve the ecological condition of small river basins in specified region.

The purpose. To determine basic water-environmental problems of rivers of Western Polissia of Ukraine (on an instance of water-collecting area Horyn). Methods. Dialectic method of scientific knowledge, analysis and synthesis, system generalization. Results. State-of-the-art ecological state of basin of the river Horyn is characterized. Basic water-environmental problems in water-collecting area are analyzed, in particular water deliveries of the population and branches of national economy, complex geological structure of water-collecting area, provision of water service of Khmelnytskyi atomic power plant, reclamative land development, water pollution, etc. Is established that for today water-ecological situation in basin of river Horyn is catastrophic, that influences all the sides of vital activity of the person and leads to significant ecological and economic losses. Owing to breaking the water balance river Horyn shallows. The major factors influencing deterioration of surface and subsoil waters in water-collecting area, are disposals of sewage. Except for pollution of water objects, the urgent problem demanding the solution is the acting structure of lands in the basin of river Horyn. As a result of excessive agricultural land use the areas of natural lands were sharply divided out. Conclusions. By results of the analysis of water-environmental problems in the basin of river Horyn it is established that a priority task for solving crisis situation is execution of complex assessment on transformation of ecosystem of the river with the subsequent development of nature protection measures. The solution of the given problems depends first of all on perfecting rational water management in water-collecting area on the basis of implementation of basin principle of water resources management.

Purpose – perform an ecological assessment of the quality of the rivers of Zhytomyr region (within the pool of the Pripyat river). Method. The study was conducted according to systematic observations based on the ecological classification of the quality of surface water and estuates in Ukraine, which includes a set of hydrophysical, hydrochemical, hydrobiological and other indicators reflecting the peculiarities of components of aqueous ecosystems. On the basis of common environmental criteria, the methodology makes it possible to compare the quality of water at different sites of water bodies, in water bodies of different regions. The calculation of the ecological assessment of water quality was carried out within three blocks: block of salt composition (І1), block of trophic-saprobiological (ecological-sanitary) indicators (І2) and block of indicators of content of specific substances of toxic action (І3). The results are presented in the form of a combined environmental assessment based on the final conclusions of the three blocks and based on the calculation of the integrated environmental index (IE). Results. An analysis of the modern ecological state of the rivers of the Zhytomyr region was carried out (within the Pripyat River Basin) and an assessment of the quality of their water according to the relevant categories. The results of observations on the qualitative state of surface water of the rivers of the rivers, uz, yarn, norin (within the Zhytomyr region) indicate their satisfactory condition. Water rivers, uz, norin correspond to the III class of water quality ("satisfactory" by class, "weakly polluted" by degree of purity). The best quality of surface water is observed in the river the river (II quality class, "good" by class, "fairly clean" by degree of purity). The greatest influence on the formation of water quality in rivers studied have indicators of a trophy-saprobiological block. This is due to a high anthropogenic load in river basins, in the first place discharges of insufficient sewage. Scientific novelty. For the first time on the basis of analytical studies and stock materials, an ecological evaluation of the surface water of the rivers of the rivers, shoving, UZ, Norin within the Zhytomyr region in three blocks of indicators: saline composition, trophoprobiological parameters and specific substances of toxic action. The integral ecological index is determined. The tendencies of accumulation of pollutants in the surface waters of rivers studied are established. Practical significance. The studies have allowed to analyze and evaluate the environmental state of the rivers of the rivers of the Zhytomyr region within the pool of the Pripyat River, which will establish the environmental standards of water quality and to determine the basic directions to improve the state of water resources and substantiate the system of recommendations aimed at improving the environmental status of the studied. pools within the area.