The Saine springs near the village of Foncine le Haut, at an altitude of 892 m, and runs into the Ain river after travelling approximately 19 km.
The rare installations along the Saine have allowed to maintain an interesting diversity of aquatic habitats (comprised of large blocks, stones, gravel, etc.). Combined with the quality and undeniable freshness of its waters, the Saine is a river that is perfectly suited to the needs of the brown trout.
It is therefore one of the rivers with the most fish in the département of the Jura.