Surface waters are the third largest form of land use in Poland. The acreage occupied by surface waters in 1994 was 830,000 ha, 2.65% of the area of Poland. In comparison to 1980, this area increased due to the construction of several new reservoirs, of which the largest are Jeziorsko on the Warta river (about 42,000 ha), Laka on the Pszczynka river (12,000 ha), Dobczyce on the Rawa river (10,700 ha), and Mietkow on the Bystrzyca river (9,200 ha). Of the total acreage of inland waters, lakes cover about 317,000 ha, while rivers occupy 509,000 ha.

There are many lakes in Poland. Almost 9,300 of them are larger than 1 ha. They occupy over 1% of the area of Poland. A large majority of lakes exist in the lake district belt. In the Pomeranian Lake District there are 4,192 lakes, which occupy over 115,000 ha, while in the Masurian Lake District there are 2,561 lakes occupying altogether almost 142,000 ha. In central Poland (Wielkopolska-Kujawy Lowland and Polesie Lubelskie) there are 1,711 lakes, which cover 53,000 ha. In the rest of the country there are only 895 lakes with the total surface area of 6,800 ha.

Slightly more than half of all lakes are small, with surface area of 1 to 5 ha. They occupy 10,400 ha, only 3.3% of the area of all lakes in Poland. There are 3,510 middle-sized lakes (5 to 50 ha), which cover 37% of the total area. 1,078 large lakes, with area between 50 and 1,000 ha, make up 55% of the total area of lakes. There are only 34 very large lakes, larger than 1,000 ha, which constitute only 0.4% of all lakes but cover 76,200 ha. This amounts to one quarter of the total lake surface in Poland. There are about 60 artificial water reservoirs whose size exceeds 100 ha. The largest of them is Wloclawek Reservoir which covers more than 7,000 ha.

Most of the lakes in Poland are shallow. The depth of over 20 meters is very rarely encountered. Lakes are a transitional and short-term phenomena. All of them are slowly waning as a result of silting-up, overgrowth, erosion processes and reclamation. Depending on the initial lake depth and the rate of aforementioned processes, the waning of lakes proceeds at different speeds. The water accumulated in the lakes has a moderating influence on the environment and through increased evaporation affects the amount of precipitation. Many Polish lakes perform the role of receptors of industrial and residential effluent, which worsens the water quality. Some lakes are also polluted because of artificial fertilizers washing off of surrounding farmland.

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