Climate change is a factor of surface waters quality deterioration, thus limiting their suitability for agriculture. The study devoted to the evaluation of the waters of the Kakhovka reservoir and irrigation system revealed that climate change resulted in changes in the water quality, namely, the content of total dissolved solids (TDS) in the Kakhovka reservoir water increased from 0.30 g L-1 in 1938 to 0.43 g L-1 in 2018. At the same time, the increase in average air temperature in the growing season led to the increase of the temperatures from 15.9ºC in 1938 to 20.5ºC in 2018. We found out that the increase of air temperature by 1.0ºC leads to the increase in TDS by 0.03 g L-1. Also, there was a tendency to the increase in alkalinity of the waters in the Kakhovka water from 7.60 pH units in 1960 to 8.05 pH units in 2018. The index in the regulated canals of the irrigation system increased to 8.30-8.50 pH units. The content of soda reaches its critical values at high pH – 0.24-0.30 meq L-1 Therefore, the water from the Kakhovka reservoir and irrigation system is limited suitable for irrigation, requiring taking steps for it amelioration and continuous monitoring of the irrigated lands to prevent their degradation