The prediction of consequences for the environment from the implementation of projects on the development of tourist complexes within the Carpathian region in Ukraine and also the ecoresource provision of designing large hotel and tourist complexes is extremely relevant and needs a scientific and methodological basis. The main purpose of the research is to consider the feasibility of the designed activity in terms of eco-resource supply of a large project (over 10 thousand vacationers) of the hotel and tourist complex with water supply and sewerage subject to compliance with the requirements environmental safety with the use of authors’ scientific and methodological approaches to assessing the quantitative and qualitative indicators of the natural and technogenic safety of the hydroecosystem of the Chorna Tysa River. The research results are presented from in terms of the priority of environmental factors in relation to the economic and social factors. The authors’ calculations of the main quantitative characteristics of the natural and technogenic safety of the monitoring sites of surface hydroecosystems of the Carpathian region of the studied territory are presented in the paper. The authors have proposed the scientific approaches to defining the part of hydroresources which can be used by the designed tourist complex upon the condition of preserving the environmental safety and at the minimum technogenic risk. The component of the quantitative potential of hydroecosystems of the study area, which can be used for water supply, is theoretically determined; the maximum possible value of wastewater discharge, as a reserve for self-purification, and accumulation in catchment basins is calculated for the potential value. The authors have analyzed the obtained research data on the average, maximum and minimum concentrations of chemicals in the Black Tysa River 1.0 km upstream the urban-type settlement of Yasinia and the average, maximum and minimum concentrations of chemicals in the Black Tysa River 1.5 km downstream the urban-type settlement of Yasinia for the period 2014-2019, obtained by the Transcarpathian Hydrometeorological Center in a certified laboratory. The location of treatment facilities of the designed tourist complex is proposed