Hantan River Flood Control Dam, dam in Yeoncheon County, Gyeonggi Province

The Hantangang Dam is a gravity dam of roller-compacted concrete on the Hantan River in Yeoncheon County, Gyeonggi Province. It is 83.5 m high and 690 m long, with four spillways: a service, an emergency, a lower sediment discharge and an eco-corridor. Together they can discharge up to 1,950 m³/s, and the reservoir holds 270,000,000 m³.

The dam was proposed in 1998 after floods in the late 1990s killed 128 people, displaced over 31,000 and caused about US$900 million in damage. Initially a multi-purpose project, it was changed to flood control only in 2006 after objections from upstream residents. Construction ran from February 2007 to mid-2015, with DL E&C as leading contractor and K-water supervising.

The dam is reached via National Route 87 and Local Route 78, which were rebuilt at elevation 144 m to stay above the new reservoir. The 27 km of relocated roads include 11 bridges, several of which cross the Hantan River near the dam and give clear views of the structure. The four spillways — service, emergency, lower sediment discharge and eco-corridor — are best seen during flood season releases.

The dam appears in episode 2 of the television series Military Prosecutor Doberman, in a scene set on a bridge over the Hantan River. Its reservoir required relocating 27 km of roads, including 11 bridges, on National Route 87 and Local Route 78.