Jirkov Reservoir, drinking water reservoir in the Krušné hory, Ústí nad Labem Region, Czech Republic

Jirkov Reservoir is a drinking-water reservoir on the Bílina in the Krušné hory, in the Telšské údolí valley northwest of Jirkov. Its 190 m long, 5.5 m wide earth-and-rockfill dam, sealed with clay on the upstream face, rises 50.8 m above the terrain and holds a surface of 16.44 ha at 448 m above sea level.

The reservoir was built in the early 1960s to supply drinking water to the region and manage water flow downstream. For more than 60 years, it has worked alongside other dams across North Bohemia to ensure towns and industries have steady access to clean water.

The reservoir lies in Telšské údolí, the valley of the Bílina in the Krušné hory, and its dam and the path around the water are closed to the public except from April to October, when walkers and cyclists may use them. Above the reservoir stands the ruin of Najštejn Castle, and 2.5 km east is Červený Hrádek chateau.

The dam, its access road and the immediate surroundings are normally closed to the public. From April to October the dam crest and the path around the reservoir open to walkers and cyclists; the rest of the year access is barred. The reservoir lies in a first-degree drinking-water protection zone, so swimming and boating are not allowed.

The reservoir doubles as a small hydroelectric plant: the Jirkov station at the dam uses a Francis turbine with a maximum output of 215 kW, while the German-language sources describe a CINK Banki-system turbine rated at 142.2 kW. The outflow from the dam feeds this plant before continuing down the Bílina.