Osancheon (오산천, 烏山川) is a stream that flows through the cities of Yongin, Hwaseong, and Osan in Gyeonggi-do. It is 14.67 km in length with a surface area of 57.30㎢. The stream begins from the mountain Seokseongsan (석성산, 石城山:472m) and eventually flows into the Shingal Reservoir.