The Asan Barrage, popularly known as Dhalipur lake, was created in the year 1967 as a result of the construction of Asan barrage at the confluence of the river Yamuna & Asan through Dhalipur power house. Asan Barrage is famous for bird watching.
The Asan reservoir attracts 53 species of water birds of which 19 are winter migrants from Eurasia. During winter months 90% of the waterbird population comprises the following 11 migratory species, namely Brahminy Duck, Pintail, Red Crested Pochard, Gadwall, Common Pochard, Mallard, Coot, Wigeon, Common Teal, Tufted Duck, and Shoveller.
The Asan Reservoir is a small man-made wetland of ca. 4 sq km area, located 40 km west of Dehradun, in the west of Dehradun valley on Dehradun-Paonta road.
Geographically it is situated between latitude 30o 24'-30o 28' N and longitude 77o 40'-77o 44' E, near the confluence of the rivers Asan and Yamuna.
The barrage is 287.5 m long, the river bed being 389.4 m above sea level, with minimum and maximum water levels respectively at 402.4 m and 403.3 m asl.
The Asan reservoir exists throughout the year and is fed from the river Asan and the discharge channel of Yamuna through Dhalipur powerhouse. Although the water level is controlled, it often goes down, and swampy islands in the middle become visible, attracting a variety of marsh-loving birds like Egrets, Herons and Lapwings, etc.
The reservoir has a typical North Indian monsoon climate, with distinct summer and winter months.
summer, max.38o C, min. 14o C;
winter max. 21o C, min. 2o C;
Average Rainfall 250 cm; South West monsoon during June to September.
The aquatic vegetation of the reservoir consists of Eichhornia crassips, Potamogeton pectinatus, Typha elephantina, and Ceratophyllum demersum.
The surrounding bushes include Xanthium strumarium, Eclipta prostrata, Ipomoea sp., Mimosa pudica, Achyranthus aspera, Polygonum glabrum, P. lanigerum, Aeschynomene sp., Ageratum conyzoides, phyllanthus sp., Monochoria hastata, Mosla dianthera, and Lantana camara.
On the southern side, agricultural fields surround the barrage. Further south there is mixed forest in Siwaliks comprising principally Shorea robusta, Anogeissus Latifolia, Lannea coromandelica, Dalbergia sissoo, and Bombax ceiba.
Arrival & Departure
October November December March-end
Or Early April, Sometimes April- end