The Římov reservoir was built in 1971–1978 on the 21.85 km long Malše River (tributary of the Vltava), downstream of its confluence with the Černá Stream. The reservoir serves to supply drinking water to southern Bohemia and helps to maintain a minimum flow downstream. The dam is 47 m high and 290 m long. The volume of the reservoir is 34.3×106 m3, the catchment area is 489 km2, the average annual flow is 4.3 m3 s-1 and the average theoretical water retention time is 92 days. The Římov reservoir is a canyon-shaped reservoir with steep banks, the „tower“ for the drinking water supply is located 5 m from the dam. The Římov reservoir is protected as a source of drinking water and other uses are not permitted.

Regular surveys of the Římov reservoir in its lacustrine part began in 1979 and have continued at three-weekly intervals to this day. The Římov reservoir has been part of the Czech LTER network since 1996. The parameters investigated include physical, chemical and biological data on pelagic organisms such as bacteria, protists, phytoplankton and zooplankton. The abundance and species composition of fish is examined once a year. In addition to regular monitoring, extensive studies of pelagic organisms, their diversity, interactions and functions as well as chemical processes in the water and sediment were carried out, both in the lacustrine part and in the canyon-like section of the river near the tributary. These intensive studies were possible thanks to the proximity to the well-equipped laboratories in České Budějovice and the construction of a field station at the dam (1994).