Lake Annecy

Lake Annecy fills a glacial basin in the Pre-Alps of Haute-Savoie, left behind when the great Alpine glaciers melted some 17,000–18,000 years ago. It is 14.6 km long and covers about 27.6 km², which makes it the third-largest lake in France, and it lies at roughly 447 m above sea level. A narrowing near the Duingt peninsula divides it into two parts — the larger Grand Lac in the north, by the town of Annecy, and the Petit Lac in the south — and the whole of it is ringed by limestone mountains: the jagged Dents de Lanfon and La Tournette (2,350 m), the highest summit visible from every part of the water, rise straight from the eastern shore.

The lake's famous colour — a clear turquoise that turns green and deep blue as the bottom drops away — is not simply a gift of nature but the result of a decision. By the 1950s the lake was choking on sewage and algae; an Annecy physician, Dr Paul-Louis Servettaz, had been sounding the alarm since 1943, and in 1957 eight lakeside municipalities formed a joint syndicate to save it. Between the early 1960s and 1976 they laid a sewage collector right round the shore, under the road that circles the lake, so that waste water never reaches it. Transparency rose from about 3 m in 1957 to some 14 m half a century later, and the lake is now often called one of the cleanest in Europe among lakes with an inhabited catchment.

The water comes from a handful of mountain streams and from a hidden source: the Boubioz, a powerful spring that wells up from the lake's deepest point, 82 m down. The outflow is the short river Thiou, which runs through the canals of Annecy's old town. Two nature reserves protect the wilder shores — the Roc de Chère, a wooded rocky headland on the east bank with more than 560 plant species, and the reedbeds and marshes of the Bout du Lac at the southern end. Between them lie the villages of Talloires, Menthon-Saint-Bernard, Duingt and Sévrier, while summer water temperatures of 22–24 °C make it a lake people actually swim in.

Getting there

The town of Annecy stands at the lake's northern tip, about 7 km from its centre. The nearest airport is Annecy Mont Blanc (NCY), about 10 km away; the larger Geneva Airport is under 40 km from Annecy, with frequent coach connections. A cycle path follows much of the western shore south towards Ugine and Albertville, and passenger boats run on the lake from Annecy — the largest, the Libellule, carries nearly 600 people.