Quick answer
The dam that made Green Canyon is a genuine engineering landmark. Here are the sourced facts — height, capacity, who actually operates it — with the common myths corrected.
The emerald lake at Green Canyon exists because of a serious piece of engineering: the Oymapınar Dam, a concrete arch dam about 185 metres high on the Manavgat River.
Verified July 2026
When it was built
Construction ran from 1977 to 1984, when the dam entered operation, according to the official Akseki district governorate and the DSİ 13th Regional Directorate. You will sometimes see 1983 or 1988 on tour sites; those disagree with the official record, so we use 1984.
What kind of dam it is
It is a concrete arch dam — specifically a double-curvature concrete arch, per the Akseki governorate and the Structurae engineering database. The Akseki page gives a height of about 185 metres above the riverbed, a crest length of 360 metres, and a dam-body volume of 575,000 cubic metres. Structurae measures the 185 metres from the foundation, so we phrase it safely as "about 185 metres high."
How much power it makes
The plant has an installed capacity of 540 MW across four turbines, with average annual generation of around 1,620 GWh, according to the Akseki governorate; the four-turbine figure is confirmed by the Manavgat Chamber of Commerce. Notably, the turbines are housed in an underground powerhouse. It is a real, working hydroelectric station, not a decorative lake.
Who actually operates it — the common mistake
Here is the fact most sites get wrong. Oymapınar is not operated by EÜAŞ, the usual state generation company. According to Enerji Atlası, the Oymapınar hydroelectric plant is operated by Eti Alüminyum A.Ş. under an autoproducer licence, and its output primarily supplies the Seydişehir aluminium smelter. This is an industry source rather than a government page, so we state it as reported, not as government-confirmed — but it is the accurate correction to the widespread EÜAŞ claim.
The reservoir it created
At normal water level the reservoir holds about 300 million cubic metres and covers roughly 4.7 square kilometres, per the Akseki governorate. That is the "Green Canyon" you cruise. The Manavgat municipality's guide describes it as one of Turkey's largest dams, though it does not state the exact ranking metric, so we keep that wording soft.
A second dam downstream
Below Oymapınar sits a smaller structure, the Manavgat Dam, with construction starting in 1984 and operation from 1987, according to the DSİ regional directorate; the Manavgat Chamber of Commerce describes it as a two-turbine plant. Green Canyon boat tours run on the upstream Oymapınar reservoir, not on this lower one, so when people talk about the "Green Canyon dam" they mean Oymapınar.
Why the engineering shapes your day
The dam is not just background trivia; it is why the boat day works at all. By holding the Manavgat River back into a deep, still reservoir between natural gorge walls, the structure created a sheltered waterway that stays calm and scenic where there was once a fast river at the bottom of a canyon. That is the practical legacy of the 1977–1984 project for a visitor: a mirror-flat surface, mountain walls on both sides, and water deep enough to read as emerald. The power station keeps working underground while tour boats cruise the surface above it.
For the natural wonder the reservoir drowned, read the Dumanlı spring under Green Canyon. For the natural-versus-engineered question in full, see is Green Canyon natural or man-made.
FAQ
Who operates the Oymapınar Dam?
According to Enerji Atlası, the plant is run by Eti Alüminyum A.Ş. under an autoproducer licence, primarily to supply the Seydişehir aluminium smelter — not by EÜAŞ, as many pages claim. Since this is an industry source, we report it as such rather than as a government-confirmed fact.
How tall is the Oymapınar Dam?
About 185 metres. The Akseki governorate gives 185 metres above the riverbed, while Structurae measures 185 metres from the foundation and 155 from the riverbed. Because the sources use different baselines, we describe it simply as roughly 185 metres high.
When was the dam built?
Between 1977 and 1984, when it entered operation, per the Akseki governorate and the DSİ 13th Regional Directorate. Dates of 1983 or 1988 appear on some tour pages but contradict the official record, so we use 1984.
How much electricity does it generate?
The plant has 540 MW installed across four turbines and generates around 1,620 GWh a year on average, according to the Akseki governorate. The turbines sit in an underground powerhouse, and the output mainly feeds the Seydişehir aluminium works.