Abstract:The Apipucos Reservoir is located in Pernambuco-Brazil. Several districts of the metropolitan area use this reservoir to dispose of rubbish, waste and sewage. Dating sediments uses the 210 Pb from the atmosphere. 210Pb is a daughter of the 222 Rn, which emanates from the soil but is different from that contained in the sediment, which is in balance with the 226 Ra. The chosen model for dating sediments depends on certain conditions: in environments where the amount of sediment can vary, the Constant Rate of Supply (CRS) model is adopted. In environments where the sediments can be considered to be constant, a Constant Initial Concentration (CIC) model is applied. A 70 cm long and 5 cm internal-diameter wide core was used for sediment sampling. Samples were dried at 105 C, and about 5 g dry material was dissolved with acids. The 210 Pb and 226 Ra content was determined by their radioactive descendants' concentrations. For the second sampling point, both models could be used. The results showed an increase in sedimentation rate over the last 50-60 years. We could conclude that the top sediment interval had been there 30 years ago. We could decide that the CRS was the best applicable model.