Assan Barrage is a pristine blue-green lake, located about 40 km from Dehradun. This man-made lake is a birder’s paradise that lies at the confluence of Yamuna and Assan rivers. Almost 53 species of birds can be seen, including red-crested poacher, mallard, coot, pintail, common teal, tufted duck, etc. A bird-watching safari is a must while visiting here. The lake offers splendid boating opportunities. The best time to visit is in October, November, February and March. Assan Barrage is also called Dhalipur Lake.