The sources of the river Prosna can be found nearby Wol?cin (Rad?ów Municipality). The river’s total length is 216.8 km. Apart from the source area the river is regulated. The maximum width of the Prosna valley is 1 km, the average – 300-400 m. The river itself is ca. 5-7 m wide and ca. 0.3-1.2 m deep, with the average flow of 0.25-1.5 m3/s. The average river slope in the LAG area is ca. 1.5%, but in the spring area it is very high and reaches up to ca. 10%. Prosna has a ground-rain-snow recharge pattern, which makes it a varied flow river with summer-autumn lows and freshets during spring thaws. However, the risk of flooding is low and affects mainly the low-lying meadows.