mont Lachat, a successful renaturation project
Summer hike
mont Lachat, a successful renaturation project

mont Lachat, a successful renaturation project

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Stunning views in the surroundings of the foothills of mont Blanc…
From clear forest to alpine meadows, this loop explores mont Lachat and its diversity of environments. A hike full of history, with the old wind tunnel that was once located at the mont Lachat mountain pass and has been dismantled since. This site is a Espace Naturel Sensible, a preserved natural area with free access and information for visitors.

11 points of interest

  • The sanatoriums of the plateau of Assy

    What is that pink building perched on the other side of the valley? A former sanatorium, a health care establishment for tuberculosis treatment.
    Mountain air and sun being the essential healing ingredients of respiratory diseases, the Plateau d'Assy was chosen at the beginning of the 20th century as the perfect location to build several of these treatment centers. With its exposition to the south, its altitude and its isolated location, their fame was worldwide.
  • The glacier valley of Chamonix

    This U-shaped valley was formed more than 10,000 years ago by glaciers which then reached as far as Lyon ! All glaciers advance by deforming and sliding under their own weight: the front of the glacier melts with the warmer temperatures of the valley, while the rear is renewed by the compaction of snow at altitude. The movements of these gigantic streams of ice are impossible to notice with the naked eye and have eroded and hollowed out the valley in the location that now hosts the town of Chamonix.
  • Small patrimony

    The aircraft wind tunnel of mont Lachat

    In 1937, a wind tunnel was built here at the Mont Lachat pass to test aircraft engines in extreme conditions (wind and cold). After various uses, the place had turned into an industrial wasteland. In 2015, thanks to multiple funding, the site was rehabilitated and renatured: an ambitious project, in particular thanks to a low impact transport system (of workforce, machinery, and waste disposal) using the Mont-Blanc Tramway.
  • Small patrimony

    A renaturation project, one of a kind

    After the dismantling of the buildings, the bare soil was reseeded with a mix of local seeds (grasses, flowering plants, etc.): pioneer species providing a substrate, allowing other species to grow. Approximately 5,000 m² were restored! This renaturation project is also a unique scientific experiment.
  • Fauna

    The Grounhog, equipped for mountain environments

    Appearing as a gentle stuffed animal, Groundhogs are actually truly warriors, adapted to the harsh mountain conditions. When the summer comes, its top goal is simple: eat as much as possible to build up fat reserves for the winter season. In order to resist during hibernation, its aim is to gain weight, starting from 3 kg and going up to 7. This is not a problem, Groundhogs are equipped for survival: a robust silhouette, nimble and clawed paws to grip food (plants, earthworms and insects), sharp teeth to cut and nibble.
  • Peak

    Mounteneering and overfrequentation

    The Mont Lachat mountain pass is located on the usual route for the ascent of Mont Blanc, the highest peak in Western Europe. This mountaineering route requires specific and compulsary equipment. Between 15 000 and 20 000 people make their attempt every year. An overfrequentation which is not without consequences for this fragile environment: disturbance of the fauna, trampling, incivilities (waste, etc...).
  • Flora

    Espace Naturel Sensible (ENS), a protected area

    You are entering a « Espace Naturel Sensible” (ENS), a preserved natural area.
    ENS-labelled sites are recognized for their highly-valued environmental features (fauna, flora, landscape) which are threatened or made vulnerable by urbanization or the development of activities.
  • Fauna

    The Golden Eagle, a true symbol

    A majestic bird, very useful for the regulation of rodent populations by consuming them, it has always fascinated humans as much as it has been feared. It has often been chosen as a symbol of power, as shown by the numerous coats of arms, the flags of current or former states (Napoleonic Empire, Germany, etc.).
    It is also a source of inspiration for artists, of admiration, even of worship in different civilizations.
    However, it has long been persecuted because it was considered to be "harmful". Nowadays, it is protected, like all raptors in France.
  • Fauna

    The common Kestrel

    This small diurnal raptor belongs to the falcon family Falconidae: this name comes from the scythe-shaped wings (falx in latin means scythe). These long and pointed wings enable a fast and powerful flight.
    The Common Kestrel can be found from the seaside to the mountains as long as its prey (small rodents, batrachians and other insects) is present in sufficient amounts.
  • Fauna

    The behaviour of chamois

    It tends to spend the winter in the forest, and roams the alpine dry grasslands in the summer: this is what is called the seasonal altitudinal migration.
    When disturbance occurs, it adopts the same escape strategy as when faced with predators (wolf, lynx, eagle for the juveniles): it flees at high speed down the slope! This costs a lot of energy, which is needed to survive in low temperatures and with a lack of food during the winter, or during the breeding season. So of you come across a chamois, give it time to move away quietly.
  • Fauna

    Chamois or Ibex?

    With a heart twice as big as ours and blood containing three times more red blood cells, the Chamois is a true athlete able to climb within 5 minutes what a trained human would do in an hour! The Alpine Chamois can be recognized by its almost hook-curved horns, and more specifically by the two dark lines running from its eyes to its muzzle (the rest of its head is lighter).

    Be careful not to confuse it with the female Ibex which has an almost uniform colored coat, even on the head! The long ridged and backwards curved horns of the male Ibex make it easy to distinguish it from the chamois’ silhouette.


  1. On the plateau of Bellevue, pass behind the restaurant La Chalette and continue on the dirt road on the right leading steeply up to the ridge of Mont Lachat, then up to the summit, near the orientation table.
  2. To go back down take to the right of the orientation table and to join the path along the rails.
  3. At the intersection, take the down going path on the left, not following the railway. Follow this path on the slope of Mont Lachat, until you reach the starting point at Bellevue.
  • Departure : Tram station BELLEVUE, line TRAMWAY du Mont-Blanc
  • Arrival : Bellevue, Saint-Gervais
  • Towns crossed : Saint-Gervais-les-Bains

Altimetric profile


Be careful, this itinerary is not dangerous but it can be impressive because of its steep passages, or near the void (with railings). Not suitable for people who suffer from vertigo.

Access and parking

The easiest access is by the Tramway du Mont-Blanc, stop: BELLEVUE

Other possible access: Les Houches-Bellevue cable

From the Crozat parking lot (+ 45 min walk): To get to theparking from the center of Saint-Gervais, take road D902, then turn left on the road to Bionnassay, you will then have to walk 45 minutes to arrive at the start of the hike.

More information

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