The subject of research is the ‘Goczałkowice’ reservoir damming the waters of the Vistula river. The
reservoir was built in 1950-1955 in the Upper Vistula valley, mainly to supply water to a nearby industrial
conurbation, inhabited by over 3 million people. The ‘Goczałkowice’ reservoir has multiple functions, except
drinking water storage these are: flood control, compensation of low-flow, fisheries management,
environmental protection and recreation [4].