Purpose <p>For the first time, the seasonal and spatial distribution of selected phthalates and one adipate was determined in the water and bottom sediments of the Nakło-Chechło reservoir (southern Poland). The study aimed to comprehensively characterize selected pollutants in a non-flowing reservoir with a residual forest catchment area and a high tourism impact.</p> Materials and methods <p>Four times a year, representative of each season, water and bottom sediment samples were collected along the large axis of the studied reservoir. Environmental samples were analyzed for the concentration of selected phthalates including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP) and bis(2-ethylhexyl) adipate (DEHA) by gas chromatography-mass spectrometry. Moreover, the temperature, oxygen concentration, pH, electrical conductivity, chemical oxygen demand, and concentration of total, inorganic, and total organic carbon were measured in the waters. In the bottom sediments, pH, redox potential, dry mass, dry organic mass, and dry mineral mass were measured.</p> Results and discussion <p>The sum of tested compounds in the water ranged from 3.59&#xa0;µg L^− 1 to 68.6&#xa0;µg L^− 1, while in bottom sediments from 338&#xa0;µg kg (dry mass: DM)⁻¹ to 1170&#xa0;µg kgDM^− 1. Different seasonal variability was observed, with the highest concentrations of total plasticizers in winter and spring, in water and sediments respectively. Spatial variability studies have shown an increase in the sum concentration of phthalates and adipate in the reservoir water along the large axis of the reservoir and similar distribution of congeners in sediments. In turn, spatial variability in the water column indicated no significant differences in the concentrations of the tested compounds, probably due to the reservoir’s small depth and the mixing of water masses. DBP and DEHP dominated the sediments.</p> Conclusions <p>The lack of surface water inflow to the Nakło-Chechło reservoir and the residual forest catchment most likely have a decisive effect on the level and distribution of the tested pollutants in the reservoir. Atmospheric deposition, increased tourist activity in the reservoir area, and consequently, the quality of surface runoff also affect the concentrations and spatial distributions of the plasticizers.</p>