Lac de la Gimone, reservoir in France

Lac de la Gimone is a reservoir formed by a 650 m earth-fill dam across the Gimone valley, stretching 6 km up to Boulogne-sur-Gesse. It lies across four communes in Haute-Garonne and Gers, with a wooded hillside on the east side and the D 12 and D 228 along its shores. Its 280 ha of water leave broad tan mudflats and sandbars exposed at low levels, where cattle sometimes stand.

The dam across the Gimone valley, about 650 m long, was commissioned in 1991 (the Dutch source gives 1992) to store rainwater and water from the Pyrenees for farming in dry summers beyond the Lannemezan plateau. It also supplies cooling water for the Golfech nuclear plant and is managed by the CACG. In 2019 and again in 2021 the CACG was convicted for releasing flows below the legal minimum downstream in 2012 and 2017.

The lake's name comes from the Gimone, the river it dams; the Neste canal feeds that river year-round to support low-water flow. The Saint-Blancard leisure base hosts swimming in summer and seasonal sailing, pedal boats, paddleboards, rowing and kayaks, plus an inflatable water park. Anglers fish for carp, roach, zander, perch, trout and pike, day or night, from shore or boat.

The lake is easily reached by car with parking available nearby. The walking paths around the water are flat and straightforward, making them accessible for visitors of all ages and fitness levels.

The dam that holds the lake is about 650 m long and its spillway lies in Péguilhan. The reservoir holds 25 million cubic metres and covers 280 ha, and its water also cools the reactors of the Golfech nuclear plant. In 2019 and again in 2021 the managing company CACG was convicted for releasing flows below the legal minimum downstream.