The Asan Conservation Reserve (400 m) in Dehradun district at the bank of river Yamuna is India’s first conservation reserve, established in 2005. It covers 4.5 sq.km. area, this is situated at the junction of the Yamuna and Asan rivers. The Asan river is a river fed by the streams of the western part of the Doon valley. The northern section of the river is known locally as the ‘Tons nadi’ (a misnomer, the actual Tons nadi is much larger and flows into the Yamuna in the Jaunsar Bawar region at Kalsi); originates from the southern slopes of Mussorie. There are several streams here, Asan is listed as an Important Bird Area (BNHS and BirdLife International). Its is popular for winter migrated birds.