The Římov Reservoir (48○50’56”N, 14○29’26”E) is a dimictic, deep valley reservoir with a surface area of 2.06 km2 and a volume of 34.5 × 106 m3. It is 13.5 km long with maximum and mean depths 43 m and 16.5 m; respectively. Mean retention time is ~100 days. It was built in 1974–78 as a storage reservoir for drinking water supply by damming the River Malše, the main reservoir tributary accounting for 90% of the water inflow.
The reservoir is filled by headwaters from a medium-sized hilly catchment (489 km2) covered mostly by forest and partly with arable land, pastures and meadows. The dam itself, completed in 1977, is 47 m high and 290 m long at crest. The outflow system of the reservoir dam consists of a gated spillway and a two bottom outlets. A small hydropower plant with a maximum capacity of 1 MW is installed in the dam. At the dam, there is multilevel outlet tower providing raw water for a drinking water plant situated 7 km downstream. The reservoir became fully operational in 1979.
Since 1979, the monitoring program has been conducted by the Institute of Hydrobiology residing in the nearby town of České Budějovice regularly over three-week intervals at the fixed sampling site near the dam. The parameters studied include physical, chemical and biological data on pelagic organisms like bacteria, protists, phytoplankton and zooplankton. Data on fish abundance and species composition have been obtained on yearly basis since 1983. Since 2008, seasonal measurements of spatial heterogeneity of physical, chemical and biological parameters in the reservoir (both in longitudinal and vertical planes) have been conducted. Besides regular monitoring, a lot of detailed studies combining classical limnological approaches with modern fluorescence and molecular methods provide a deeper understanding of the trophic interactions across the aquatic food webs and the reservoirs functioning.
Futher reading: Brief history of ecological research into the Římov reservoir