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cesspools and primitive toilets are a threat to groundwaters and the lakes. There is a lack of sanitary arrangements largely near intensively-utilized lakes. Other pollution sources are \vild’ garbage dump encountered most often in forests near camping areas.

THE INFLUENCE OF COAL-MINING

The coal deposits of Lublin District were discovered in 1964—1971 on the basis of studies conducted according to the results of Samsonowicz’s investigations (Porzycki 1984). Their presence was noted in an area of 4000 km² extending NW-SE from Parczew to Hrubieszów — 180 km in length and 18—37 km in width, which is called the Lublin Coal Basin. Three regions of coal exploitation have been established: northem of 450 km², central — 240 km² and Southern — 320 km². The central region was exploited first. This area constitues a wide transitional zonę between the Lublin Upland and Polesie. The shafts of the first coal-mine were built in close proximity to the south—west part of the Lakę Region at Bogdanka and Nadrybie (Fig. 8). They were located 3 and 2 km south of Nadrybie Lakę, respectively, despite the protests of naturalists, who pointed to threats to the environment resulting

Fig. 8. Situation of lakes and location of the 'Bogdanka’ colliery 1 — Wieprz-Krzna canal, Puchaczów — Wola Wereszczyńska conveyer, 2 — rivers,

3 — settling tanks for minewaters and sites of their discharge into the Świnka river, 4 — lakes and their maximal depths, 5 — shafts of the 'Bogdanka' colliery, 6 — a shaft of the 'Stefanów' colliery (building stopped), 7 — rangę of the coal field, 8 — area of found land subsidence