Abstract: The dammed lake Kozłowa Góra was created in 1939, and has been utilized as a fresh–water reservoir. The lake is situated in Upper Silesia. The paper describes this artificial water reservoir, its sediments, the probes used and the sediment cores collected for analyses of activities of 210Pb. The cores of sediments have been collected in 13 sites, 6 of them along the dam. Sediment cores were gained by the freezing method. 210Pb method has been widely used in dating of lake sediments. The activity of allochthonous 210Pb decreases according to the law of radioactive decay with the half–life of T= 22.26 yr. Thus its activity can be used to determine the age of sediments within the range of several half–lives (100-150 years). Here we present preliminary 210Pb measurements in sediments of dammed lake Kozłowa Góra.