Abstract <p>The article presents the results of a study of the lakes of Pinezhsky Nature Reserve, which is part of specially protected natural areas (SPNA). The lakes Sychevo, Zheleznoye, Kumichyovo and Pershkovskoye were studied. The characteristics of the hydrological and hydrochemical parameters obtained from observations in March 2022 and 2024 are provided. Changes in the hydrogen index (pH), mineralization, and biogenic elements (nitrate, nitrite, ammonium nitrogen, phosphate phosphorus and silicon) are shown. The compliance of the obtained parameters with the regulatory requirements for the quality of lake waters is assessed. Studies have shown that the waters of Lake Sychevo and Lake Zheleznoye are classified as low- mineralization reservoirs, Lake Pershkovskoye as high-mineralization reservoirs, and Lake Kumichyovo as highly mineralized reservoirs. The pH values in Lakes Sychevo and Zheleznoye are classified as slightly alkaline to neutral waters. Lakes Pershkovskoye and Kumichovo have a slightly alkaline water reaction. The concentrations of phosphorus, nitrogen and silicon salts over the entire observation period did not exceed the maximum permissible values ​​for fishery reservoirs. The results obtained allow us to conclude that there is no noticeable anthropogenic impact on the reservoirs in question. The purpose of the work was to identify the hydrological and hydrochemical features of the lakes under study. The data obtained can be used as background data for assessing the negative impact in the case of anthropogenic load on the river basin.</p>