Orto-Tokoy Reservoir — a reservoir on the Chu River.
It is located 2 km west of the village of Orto-Tokoy, on the border of Naryn and Issyk-Kul regions, at an altitude of 1700 meters. The construction plan for the reservoir was approved by the decree of the Central Committee of the All-Union Communist Party (Bolsheviks) and the Council of People's Commissars of the USSR on March 19, 1940. Construction began in 1941 and was completed in 1960. The elevation above sea level is 1700 m. The surface area of the water is 26 km², and the volume is 470 million m³. The length is 18 km, the maximum width is 5 km, and the maximum depth is 47 m. The height of the dam is 52 m, the length is 365 m, and the width is 6 m.
The Orto-Tokoy Reservoir is intended for seasonal regulation of the flow of the Chu River, for the irrigation of 220,000 hectares of land in the Chui Valley of Kyrgyzstan and 80,000 hectares in Kazakhstan. The reservoir was constructed under complex engineering and geological conditions of the highlands, in a zone of nine-point seismicity. It is situated in the Orto-Tokoy basin, which is constricted by the mountain ranges of Kyzyl-Ompol and Archaly-Mazar.
The earth dam is built from local coarse-grained mixed soils. The upper slope of the dam is reinforced with broken stone, while the lower slope is covered with large gravel.
There is a tunnel outlet through which the necessary amount of water is supplied to the Chu River during the growing season. The design of the outlet guarantees the closure of water for filling and emptying the tunnel at any water levels in the reservoir. The tunnel outlet is constructed in rock with a concrete lining 32 cm thick and an internal iron shotcrete ring 8 cm thick. At the end of the tunnel, there are two conical gates with a diameter of 2.2 m, which allow the release of water from the reservoir.
The catastrophic spillway is designed for the automatic release of water when the reservoir fills above the Normal Pool Level (NPL).
On the shores of the reservoir, where the water temperature in summer does not rise above +15 degrees Celsius, fishing enthusiasts from nearby settlements and visitors to the country gather. The reservoir is home to species of carp: marinka and osman, as well as trout and sig – types of commercially valuable fish from the salmon family.
The water surface impresses with its vastness and tranquility, while in different places the water changes its color: somewhere it is a gentle blue, somewhere emerald, and somewhere it is almost black.
The stunning view of the reservoir is enhanced by the gray-brown mountains that surround it.