Lac des Brenets drying up after record Swiss summer

Lac des Brenets, on the France-Switzerland border, has largely dried up after a record-breaking hot summer, halting pleasure boat tourism and exposing much of the lake bed.

The Doubs river normally forms the lake at Les Brenets, where it begins to mark the border between France's Franche-Comte region and Switzerland's Neuchatel canton. The lake ends at a 27-metre waterfall, which has stopped flowing.

The lake has dried up because of a combination of geological fissures that drain water underground, below-average rainfall and repeated heatwaves. June, July and August were each the hottest ever recorded in Switzerland since measurements began in 1864.

Yvan Durig, owner and captain of the Lac des Brenets navigation company, said boat operations had to stop on July 20, in the middle of a season when the company would normally carry 200 to 300 people a day.

Durig said the deepest remaining basin has about nine metres of water, compared with a normal depth of 25 to 30 metres. The water line is dropping around 20 to 22 centimetres a day.

On October 1, the lake fell to an elevation of 735.34 metres above sea level, 14.66 metres below where it should be. It was expected within days to surpass the 1906 record drop of 15.35 metres.

French and Swiss authorities set up a task force in 2022 to study ways to limit water draining into fissures, but locals say decisive action has not followed.