Lac de Saint-Agnan, Artificial lake in Morvan Regional Nature Park, France.

Lac de Saint-Agnan is an artificial lake in the Morvan park region surrounded by forests and meadows in Burgundy. The water fills a large basin in upland terrain where several small streams flow together.

Lac de Saint-Agnan was inaugurated in 1969, the last of the great dam lakes of the Morvan. Its dam, at the northern end of the lake, is 160 m long and 16 m high, built of compacted granite sand. The lake was drained in October 2002 and again in 2008.

The lake's name comes from Saint-Agnan-en-Morvan, the village at whose centre it lies. Anglers come for pike, zander, perch, roach, mirror carp and tench, some fish exceeding 15 kg. Sailing, windsurfing, canoeing and pedal boats are practised, while motor navigation is banned.

A waymarked path circles the lake over 9 km, with gently sloping shores that can be hard to reach in places. Motor boats are not allowed on the water, but sailing, windsurfing, canoeing and pedal boats are practised there. The dam stands at the northern end, 160 m long and 16 m high.

The lake lies on the Cousin, and its 160 m dam at the northern end is built of compacted granite sand. Around the site of the old earth-and-stone dike, the bed is cluttered with stone blocks and many tree stumps, a detail anglers know well.