Water reservoir Kořensko, body of water near the village of Neznašov, South Bohemian Region, Czechia

The water reservoir Kořensko is a concrete weir on the Vltava at river kilometre 200.405, about two kilometres below the mouth of the Lužnice, within the backwater of the Orlík reservoir. Its four 20-metre fields are closed by a hollow steel flap 4.8 metres high, and a small hydroelectric plant with two Kaplan turbines stands on the left bank between the weir and the lock.

The Kořensko dam was built between 1986 and 1991 as a measure to manage the thermal water discharge from the Temelín nuclear power plant. Since its opening, it has played a central role in stabilizing water flow in the Vltava River.

The name comes from the settlement of Kořensko, which disappeared when the Orlík reservoir was built. The weir's concrete body forms a submerged step: it holds water only while the Orlík level stays below 354 m above sea level, and above 353.05 m it lies under the reservoir's backwater.

The weir sits at river kilometre 200.405, about two kilometres below the mouth of the Lužnice, and is submerged when the Orlík reservoir exceeds 353.05 m above sea level. The lock on the left bank, 45.0 by 6.0 m, takes vessels up to 300 t and has operated since 2000.

A navigation lock on the left bank allows ships up to 300 tons capacity to pass through the dam, enabling regular boat traffic since opening in 2000. This infrastructure connects river transport functions with modern hydroelectric regulation.