The Ain crosses the Haut-Jura Regional Nature Park. The Vouglans dam has created an artificial lake bordered in places by small limestone cliffs. On the edge of the Bois de la Reflèche in Moirans-en-Montagne, many small streams cascade down to the lake. The forest extends over 3 212 acres (1,300 ha) and is the second largest communal forest in the Jura department. It is home to a significant biodiversity of mammals (lynx, forest cats, roe deer) and birds (peregrine falcons, tawny owls, great spotted woodpeckers, etc).