The paper studies hydrochemical characteristics of waters of the Salgir and Biyuk-Karasu Rivers in summer, when the anthropogenic load is increased. Data were obtained on dissolved oxygen concentration, five-day biochemical oxygen demand (BOD5), alkaline permanganate oxidizability, concentrations of silicate, mineral and organic forms of nitrogen and phosphorus. The samples were collected in July, August and September 2023 in Simferopol and in the Krasnogvardeisk, Nizhnegorsk and Belogorsk regions in the Republic of Crimea. The analyses were performed according to the generally accepted methods. Compliance of the obtained results on hydrochemical indicators with water quality regulations was assessed. A high level of oxygen content was noted at all stations. BOD5 values varied from 0.98 to 3.34 mg/L (the village of Molochnoye) and exceeded the limit for fisheries by up to 1.6 times. The oxidizability values exceeded the maximum allowable value by 2 to 4 times. The concentrations of the mineral forms of nitrogen did not exceed maximum permissible concentrations, except for nitrite concentration (maximum exceedance by 2.8 times). The phosphate concentration exceeded the maximum permissible concentrations near the villages of Novogrigoryevka and Molochnoye (maximum by up to 5.6). The study results allow determining the areas of Molochnoye and Novogrigoryevka as most polluted.
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