This work presents the first estimate of the radioactivity and sediment deposition rate of the Drenova reservoir. The radioactivity and sedimentation rate were computed applying the 210Pb and 137Cs methods. Samples of 210Pb and 137Cs were taken from four boreholes drilled in the Drenova reservoir in June 2010. Vertical distribution of the natural and artificial radionuclides in four boreholes was examined using a gamma spectrometry measurement with HpGe detectors, Gamma X type (10 keV-3 MeV). Activities ranging from 122-8 Bq/kg were found for 210Pb, and from 140-0.8 Bq/kg for 137Cs. The sedimentation rate in the Drenova reservoir varied from 1.96 to 2.90 cm per year for unsupported 210Pb and 0.47 to 5.33 cm per year for 137Cs.