The Studen Kladenets Reservoir (язовир „Студен кладенец“) is the third largest reservoir by volume in Bulgaria after Iskar Dam and Kardzhali Dam. It is situated on the river Arda, and is created behind the Studen Kladenets dam, 30 km south-east of the town of Kardzhali. There are another two dams of the Arda - Kardzhali Dam to the west (upstream) and Ivaylovgrad Dam to the east (downstream).

Studen Kladenets
Studen Kladenets Dam
Studen Kladenets
Coordinates	41°38′28″N 25°32′48″E / 41.64111°N 25.54667°E / 41.64111; 25.54667
Lake type	reservoir
Primary inflows	Arda, Varbitsa River
Primary outflows	Arda
Catchment area	3,707 km2 (1,431 sq mi)
Basin countries	Bulgaria
Max. length	29 km (18 mi)
Max. width	1.5 km (0.93 mi)
Surface area	27.8 km2 (10.7 sq mi)
Max. depth	60 m (200 ft) (from dam height)
Water volume	388,000,000 m3 (1.37×1010 cu ft)
Surface elevation	227 m (745 ft)

The reservoir has a total volume of 388 million m³ and a drainage basin of 3,706 km² and is 29 km long. It is situated at an average 227 m above sea level, its dam being 338 m long and 67.5 m high. The top of the dam consists of nine spillways, each one being 10.5 by 5 m. "Studen Kladenets" Hydroelectric Power Plant is situated appr. 1 km downstream of the dam. Initially the HPP had four Francis-type turbines, 15 MW each. А project for reconstruction and upgrading the HPP with another 16 MW turbine and a smaller eco-turbine underwent and after the completion, the total output reached 85 MW with annual production of 165 GWh of electricity.

Studen Kladenets reservoir is an attractive place for fishermen, where rudd is caught in great numbers. "Studen Kladenets" stands for "a cold well" in Bulgarian .