Lac Noir, reservoir in France

Lac Noir is a reservoir in the Vosges mountains, situated in a high valley surrounded by forested slopes. The water is held back by a dam and serves purposes related to hydroelectric power generation and water management for the region.

Lac Noir is a glacial lake naturally dammed by a moraine. Between 1928 and 1934, engineer René Koechlin added a 15-metre dam-dike and linked it to Lac Blanc by a 4.6-metre pressure tunnel to form a pumped-storage plant. On 4 January 1934 a pipe burst, killing nine workers; the plant ran from 1938 until a 2002 failure, and the powerhouse was demolished in 2014.

The area is best explored on foot, as hiking trails make the reservoir accessible from various vantage points. The terrain is hilly and weather can change quickly, so appropriate gear is advisable.

The lake hosted the first pumped-storage plant in France, built by René Koechlin between 1928 and 1934, with the Lac Blanc as upper reservoir. On 4 January 1934 a pipe burst at start-up, killing nine workers; a memorial stands by the shore. The plant closed in 2002 and its powerhouse was demolished with explosives on 6 August 2014.