Lake Chalain, the largest of the 7 Lakes
Nestled in the heart of the Jura Mountains, Lake Chalain is the largest of the seven lakes in France (Lakes Narlay, Ilay, Grand and Petit Maclu, Chambly and du Val). It is, in fact, the second largest natural lake in France!
Formed during the last Ice Age, Lake Chalain covers an area of 232 hectares, stretching over 3 km in length and approximately 1 km in width. In some places, its depth reaches 30 metres. Surrounded by limestone cliffs rising 60 to 80 metres high, it offers an impressive spectacle.
Lake Chalain is fed by an underground network of springs and watering troughs originating from the surrounding high plateaus, notably Lakes Narlay and Vernois. To manage flooding, a 2-kilometre canal, the Bief de l’Œuf, was constructed. This canal is also equipped with a turbine to produce electricity for the EDF power plant before releasing the water into the Ain river.
The ancient lakeside village of Chalain
Since prehistoric times, this magnificent lake has fascinated humankind. The ancient lakeside village of Chalain was discovered on its western shore in the early 20th century during the construction of the Bief de l’Œuf canal. Further excavations, carried out in 2000, revealed the remarkably well-preserved remains of an entire village of stilt houses, inhabited continuously between 4000 and 750 BCE.
Archaeologists unearthed an incredible variety of artifacts: tools, weapons, clothing, pottery, and objects made of wood and leather. Buried for millennia in waterlogged sediments, these objects were protected from the air by an anaerobic environment, which prevented their decomposition. As a result, many of them were found in excellent condition. Among the most remarkable discoveries is a 10-metre-long oak canoe, carved from a single tree and dating back to around 1000 BCE. It was found resting on the remains of ancient stilt houses.
Unfortunately, hydroelectric projects in the mid-20th century caused a drop in the lake’s water level, exposing many of the remains to the air and accelerating their deterioration. Agriculture and tourism have also impacted the site, and archaeological excavations ceased in 2009 due to a lack of funding. However, the site, closed to the public, was listed as a Historic Monument in 1911, and the extensive archaeological area was protected in 1992. In 2011, it was officially inscribed on the UNESCO World Heritage List, thus guaranteeing its long-term preservation.
Lake Chalain, a protected natural environment
Since 1950, Lake Chalain and its surrounding land have belonged to the Jura department. The western shore is composed of unique lacustrine limestone formations that are home to rare, now endangered, plant species.
In 2023, the lake’s management changed: the water level is no longer artificially lowered, allowing the formation of a natural sandy beach. While the lake is now open to tourism and has a leisure centre, activities are strictly regulated to preserve its fragile ecosystem.
Swimming is permitted and partially supervised. Visitors can also enjoy sailing, canoeing, windsurfing, diving, and fishing. However, motorized boating is strictly prohibited to preserve the tranquility of the lake and its environmental integrity, a rule that tourists happily respect. A clearly marked naturist beach is even located on the northern shore, offering a discreet and respectful space for those who prefer a more natural experience!
And for an unobstructed panoramic view of Lake Chalain, head to the Fontenuté viewpoint!
The southern lakes: Chambly and Val
Just 7 kilometres south of Lake Chalain and the village of Doucier lie two smaller, more tranquil lakes: Lake Chambly and Lake Val. Together with Lake Chalain and the Four Lakes area to the east, they form the Seven Lakes of the Jura, each possessing its own unique charm and ecological significance.
Lake Chambly is a tranquil lake of modest size, covering 35 hectares. It is 1.1 km long and 350 metres wide, with a maximum depth of 10 metres. Since 2016, it has belonged to the Jura Hunting Federation, which actively works to protect the marshes and wild areas while maintaining public access for nature lovers and walkers.
Separated from Lake Chambly by a wooded moraine and farmland, Lake Val is slightly larger (64 hectares), 1.5 km long and 450 metres wide, and much deeper, reaching 35 metres in some places. Although it retains a wilder and more secluded character, the area welcomes hikers in the summer thanks to its proximity to the famous Cascades du Hérisson.
The presence of the Hérisson Animal Park (Parc Heria) on its southern shore contributes to its appeal. Indeed, the park’s aurochs and bison reintroduction program plays a vital role in preserving the region’s wetland ecosystems through natural grazing.
The Route des Cascades (D326) begins in Doucier, near Lake Chalain, and winds through a wooded landscape, skirting Lakes Chambly and Val before reaching the spectacular Hérisson waterfalls.
So, whether you wish to explore prehistoric remains, relax on a tranquil beach or hike through the lush landscapes of the Jura, this itinerary offers an unforgettable journey to the heart of one of the most captivating natural regions of France.
Wikimedia Commons: Header by Prankster is Domaine public – Pirogue by initiales BR is Domaine public-original de 1904 – Cliff side by PRA is CC BY-SA 3.0 – Beach by Espirat is CC BY-SA 4.0 – Lakes Chambly and du Val by Parrad.adrien is CC BY-SA 4.0
