So, Tirthan valley is a part of Great Himalayan National Park, falls just before the Kullu-Manali Tunnel. How to reach ?
well we took a over night volvo from Kashmiri Gate from HRTC Himachal Roadways towards Manali, got down at Aut just before the Manali tunnel. From Aut there are 2 options to reach tirthan.
1st is via local himachal busses heading towards Banjar that starts from 8, then 8:30, 9 and 9:30 onwards other option is hire a taxi and reach the place.