Uirimji Reservoir is Jecheon's most immediate and satisfying sight. The reservoir is an old irrigation work, but it reads today as a calm scenic lake with woods, paths, pavilions, and reflections just north of the city.
It is the easiest place to understand Jecheon's identity as a water-and-mountain town. Go early or late in the day, when the path is quieter and the lake feels less like an urban park.