Messochora Dam, Embankment dam in Mesochora, Trikala, Greece.

Messochora Dam is an embankment dam on the Achelous River in the Trikala region, built with a rock core and concrete facing to contain the river. A hydroelectric power station sits at the base of the structure to use the water flow for energy generation.

Work began in 1996 after many decades of planning that started in the 1930s, with the structure completed in 2001. This extended timeline reflects how long it took to finalize the design and secure necessary approvals for the project.

The dam is the first structure of the Acheloos diversion scheme, which also includes the Sykia, Mouzaki and Pyli dams and a 17.4 km channel. Supporters cite irrigation for cotton crops in the Thessaly plains; opponents cite the annual diversion of 600,000,000 m3 of water and the flooding of villages.

The location is reached by road leading to the dam where visitors can view the structure and surrounding river valley. Conditions vary with weather and water levels, which can change noticeably after heavy rain in the region.

The reservoir behind this structure remains empty even though construction was finished, due to unresolved legal questions and environmental concerns. This unusual situation makes it a case study in how complex modern infrastructure projects can become.