The paper focuses on the problem of sediment accumulation in dam reservoirs. The studies were conducted in Soła River dam cascade containing three reservoirs: Tresna, Porąbka, Czaniec. It plays an important role in the water management in Silesian province. It was revealed that the catchment area is improperly managed which, under the mountainous conditions, leads to surface runoff and erosion processes. Soła, especially during the floods, transports large quantities of debris that are almost entirely deposited in the Tresna reservoir. The rate of deposit accumulation in Tresna water body amounts to 0.309 million m3 per year, and in the Porąbka reservoir it is estimated to 0.042 million m3 per year. The Czaniec reservoir, as fast flow reservoir, does not accumulate deposits at all. The actions aiming at prevention of sediments accumulation are insufficient – they should be realized systemically particularly in the Soła catchment above Tresna reservoir in order to maintain its retention capability.