The storage reservoir “Besko” on the River Wisłok consists of two part: the main part, on the River Wisłok (volume of about 11 mln m3), and the other one, the side part, on the River Czernisławka – contributory of the River Wisłok (volume of about 3 mln m3). The research covered this side part of the reservoir. Physical properties of the bottom sediments were determined among others the granulometric composition according to Prószyński by use of two method: with addition of a deffloculant Na2CO3 and without, showing significant differences. Chemical properties were also determined among others the pH reaction, percentage content of organic particles and also presence of heavy metals – cadmium, copper, chromium, nickel, lead, zinc – and depending on it sediments were qualified for agriculture use. According to preliminary results the bottom sediments belong to first degree or not higher than second of chemical pollution what qualifies them for agriculture use and improvement of agricultural grounds. According to the accepted Polish standards either all agricultural crops (at zero pollution) or at the second degree of pollution with heavy metals, fodder crops, root crops can be cultivated or this grounds can be used as pastures. Increments of sediments in particular measurement sections of this part of the reservoir were determined and significant differences compared with measurements made in 1987 i.e. twenty years earlier were shown. Evaluation of the measure quantities of the deposited sediments showed that within the last twenty years the sediment increment was about 1,8 meter in the section closest to the main reservoir (from the beginning of the existence of the reservoir the increment was equal about 3,2 m). Whereas, in the forest section of the main reservoir the increments were 1,3 and 2,1 meters, respectively.