Popularly known as Dhalipur Lake, Asan Barrage was constructed in 1967 at the confluence of two perennial rivers, the Asan and the Yamuna
. The reservoir is a man-made wetland located in the west of Dehradun valley
- Paonta road. This place attracts 53 species of water birds of which 19 are winter migrants from Eurasia.
The reservoir is fed by the Asan River and the discharge channel is to the Yamuna through Dhalipur powerhouse. The marshy islands in the middle become visible when the water level lowers, attracting a variety of marsh-loving birds like egrets, herons and lapwings. The region is rich in vegetation and flora.
The climate is of the north Indian monsoon nature with distinct winter and summer months. Dhalipur Lake is well connected by road.