The Asan Barrage is a barrage in the Uttarakhand-Himachal Pradesh border region in Doon Valley, (Dehradun district), northern India, situated at the confluence of the Eastern Yamuna Canal and the Asan River[2] and about 11 km (7 mi) from Dakpathar, and 28 km.

It then moves on to Tapkeshwar Mahadev, a popular Shiva shrine before becoming a more shallow, broad valley near Premnagar.

The river proceeds south-west, receiving the waters of several streams flowing southward from the northern range spanning Vikasnagar–Mussoorie; and northward from the lower Sivalik Hills that separate The Doon Valley from Saharanpur district of Uttar Pradesh.

It flows into a relatively flat section which feeds the Asan Barrage, the waters of which drain into the Yamuna at Paonta Sahib in Himachal Pradesh.

The Bird Sanctuary was established in 1967 as a manmade wetland where rivers Yamuna and Asan converged.