Malta Hydroelectric Power Station, Pumped-storage power station in Reißeck, Austria

Malta Hydroelectric Power Station is a pumped-storage facility nestled high in the Austrian Alps that moves water back and forth between two mountain lakes. The underground power station harnesses this water movement to generate electricity during periods of high demand and pumps it back uphill when energy is abundant and cheap.

The Malta project was studied from the 1930s and planned from the 1950s; the Kölnbrein dam was built between 1971 and 1978 from 1.6 million m³ of concrete. Water pressure cracked the dam base, so from 1989 to 1992 a 65 m high, 70 m wide support arch of 500,000 m³ concrete was added to plans by Swiss engineer Giovanni Lombardi. Full impoundment at 1902 m was reached again on 4 October 1993.

The reservoirs draw tourists: hotels and viewing points stand by the larger lakes, and a bungee jump is offered off the Kölnbrein dam wall. The upper reservoir has also been used for altitude training by rowers. The site is operated by Verbund Hydro Power GmbH, a subsidiary of Verbund AG.

The complex spans the Malta valley above Gmünd and the Möll valley near Rottau, with the Kölnbrein reservoir at 1,902 m reached by a mountain road. Tourism is concentrated at the larger reservoirs, where hotels and viewing points exist; bungee jumping is offered off the Kölnbrein dam. The reservoirs have also been used for altitude training by rowers.

The Kölnbrein dam, 200 m high and 626 m wide, is Austria's tallest; when the reservoir first filled in 1979, the water's 5.4 million tonnes of pressure pushed the crest 12 cm downstream, as designed. Repairs from 1989 to 1992, planned by Swiss engineer Giovanni Lombardi, added a 65 m high, 70 m wide support arch of 500,000 m³ of concrete on the valley side, easing the load by about 22 percent. Stretching a rope from the crest is offered to visitors.