Kopruçay is a river originating from the Taurus Mountains in Isparta, Isparta, passing through narrow and deep canyons and pouring into the Mediterranean at Serik. In ancient times it was called Eurymedon.
There are two old bridges across the river. Oluk Bridge is a Roman structure thought to have been built in the 2nd century AD. The bridge has great historical importance as it connects the ancient cities of Selge and Pednelissas belonging to the Pisidian civilization and the ancient cities of Aspendos and Side belonging to Pamphylia. The bridge gave its name to the river and the canyon. There is another bridge that connects the cities of Aspendos and Side in the lower reaches of the river: Belkıs Bridge. It has seven arches, the largest of which is 17 m high. It was built by the Romans in the 4th century AD. It was destroyed by earthquakes and floods in the following centuries and was restored by Alaaddin Keykubat I in 1219-1236.
Köprüçay carries 3065 gr m³ of water per year. Beşkonak II hydroelectric power plant with an installed power of 96 MW was built on the stream. The canyon valley stretching between Bolasan village and Beşkonak district has been declared as Köprülü Canyon National Park. Fishing is also done in the region, where picnics and camping are also possible. Köprülü Canyon is 14 km long and 100 m high. It is one of the most important rafting spots in Turkey.
At a pH of 8.09, the stream is alkaline and suitable for aquatic living conditions. The average temperature was 4.3°C in January and the highest value was 16.4°C in July. The river is home to the endemic fish species Capoeta antayensis and Pseudophoxinus fahrettini.
An irrigation system was installed in the lower part of Köprüçay. The entire Serik plain and a part of the Manavgat plain are irrigated.