Dlouhé stráně Hydro Power Plant, Pumped-storage power station in Loučná nad Desnou, Czech Republic

Dlouhé stráně Hydro Power Plant is a pumped-storage facility in Loučná nad Desnou featuring two reservoirs positioned at different elevations. The system generates electricity by moving water between these reservoirs or stores energy for later use.

Work on the Mravenečník massif began in 1978, but the government slowed construction in the early 1980s and the outcome stayed uncertain. A 1985 redesign replaced four separate turbine-and-pump sets with two more powerful reversible turbines, and completion was approved only in 1989. After delays and a turbine fault, the plant entered service on 20 June 1996.

In a 2000s poll by the news portal iDNES.cz, the plant was named one of the seven architectural wonders of the Czech Republic, and it is among the most visited sites in the Hrubý Jeseník mountains. The upper reservoir on the summit of Dlouhé stráně, at 1,350 m, can be reached on foot and is ringed by safety railings along its crown.

The plant sits inside the Jeseníky protected landscape area, with the upper reservoir on the summit of Dlouhé stráně at 1,350 m and the lower reservoir on the Divoká Desná about 1.5 km to the northeast. The underground machine hall lies in the Mravenečník massif between them. The upper reservoir's asphalt seal was supplied from Albania and laid by the Bratislava firm Slovasfalt.

The facility houses one of Europe's most powerful reversible water turbines, rated at 325 megawatts for electricity generation. The vertical separation between the two reservoirs exceeds 500 meters, amplifying the force of descending water through the system.