Békésszentandrás Weir, Hydroelectric power station and weir along Hármas-Körös River in Békésszentandrás, Hungary.

The Békésszentandrás Weir is an infrastructure facility that spans the Hármas-Körös River, containing locks and turbines for electricity generation. The structure manages water levels and allows boats to pass between different water elevations on both sides.

The weir was built to meet the need for hydroelectric power generation and river management, transforming the economic function of this region. It marks a period when local infrastructure along the Hármas-Körös was modernized.

The weir was named after Horthy István, the deputy regent who died shortly before its 1942 inauguration by Miklós Horthy. Its water level made possible rice growing, and rice is still cultivated around Szarvas. In summer anglers gather below the structure to fish with spinners.

The weir stands on the Hármas-Körös at the Békés–Jász-Nagykun-Szolnok county line, on the border of Békésszentandrás and Mezőtúr. In summer the Körös-vidéki Környezetvédelmi és Vízügyi Igazgatóság usually keeps the impoundment at 4.85 m, lowered in flood conditions; the maximum is 5 m. The lock is 16 m deep and wide enough for the largest barges.

The Dögös-Kákafoki backwater, Hungary's fifth-largest standing water, branches off above the weir and returns below it through regulated sluices. Because summer levels differ by 4.85 m, the water exchange runs by gravity, rare in Hungary, and the backwater's last 30–40 m drops steeply with rushing water.