The oldest functional dam in South Bohemia dammed the Černá river (Black) near the village Soběnov about 8 km east of the town Kaplice. It worked from 1925 till the big flood in August 2002. After the flood it was completely reconstructed.

The stone dam was 21 m long and it held the 3.9 ha large reservoir with 73.5 thousand cubic metres of water.

The reconstructed dam is 90 m long, at the top it is 3.5 m wide and 11.5 m high. The area of the lake is 4 ha and it takes about 73 thousand cubic metres of water. The riverbed behind the dam was strengthen with stones.
The dam is constructed for the production of electricity in the small hydro power station, which was built in the valley of the Černá river. Water run from the dam via the underground pipeline with a drop of 59.5 m. There are two Francis turbines in the power plant (2×600 W).

Access to the dam is possible along the road from Kaplice to the small town Benešov nad Černou, by turning left about 2 km behind the small village Hradiště. The other ways are along the red marked path from Kaplice past the ruins of the Sokolčí castle or along the yellow sign from Benešov nad Černou.

The instructional trail Údolím Černé ("Through the Valley of the Černá river") begins near the dam and the path of the instructional trail Paměti Slepičích Hor ("Memory of the Slepičí Hory mountains") passes the dam.