Lac de Pormenaz: an oasis of biodiversity
Summer hike
Lac de Pormenaz: an oasis of biodiversity

Lac de Pormenaz: an oasis of biodiversity

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Smells, colors, and a beautiful view of the mont Blanc massif: come and enjoy the beauty of the lake
The temptation is so great to discover a lake with changing reflections, with an island in the middle, and nestled, during the summer, in a flowery hollow of rhododendrons. On your way, you can enjoy the captivating perspective of the Mont-Blanc. At the lake and on the way back, you’ll be pleased by the charming view on the Rochers des Fiz and the Aravis massif.

22 points of interest

  • Fauna

    The Griffon Vulture

    It visits the Haute-Savoie region during the summer. The species is monogamous, that is to say that couples stay together for their entire life!

    This bird lives in colonies of different sizes, the closest of which are located in southern Vercors. Especially the young individuals who explore new territories. To feed, this bird is also able to cover hundreds of kilometers thanks to its gliding technique, depending on favorable weather conditions.
  • Fauna

    The Golden Eagle

    Everything about this bird is exceptional! With a wingspan up to 2 meters, each couple controls a territory as big as 10 000 football pitches! Its X-ray eyes detect prey movements for over 1 kilometer of distance. Its eyes are like magnifying glasses that magnify 6 to 8 times what its perceives and it has a 240 degrees field of vision. In addition to colors, it is able to detect ultraviolet light, a major asset for this great hunter who can swoop down on its prey at a speed of 350 km/h. But no one is perfect: it misses 9 prey out of 10!
  • Fauna

    The Rock Ptarmigan

    This species, using mimicry, is able to transform its plumage according to the seasons, becoming visually part of the landscape. During the winter, its plumage is pure white; during the summer, it has brown and black spots on the top; in autumn it is grayish flaked with white on the top.
    Its name, which means "hare's foot", refers to its foot digits covered by fuzz in the winter!
    It is one of the most endangered bird species in the Alps.
    Every year the nature reserves of Haute-Savoie, in collaboration with "L'Observatoire des Galliformes de Montagne", carry out population monitoring in order study their evolution.
  • Fauna

    The Black Woodpecker

    It is the largest of the 8 woodpeckers present in France. Originally an exclusive mountain species, it is now also found in the valleys! Indeed, it adapts to both deciduous and coniferous forests, as long as they cover large areas and include dead wood and old trees with large diameters.
    It is easily recognized by its entirely black plumage enlivened by a bright red spot, limited to the nape on the females and more extensive on the males.
  • Fauna

    The Hazel Grouse

    It is the smallest and most discreet of the mountain Galliformes species.
    It is much less known than the Black Grouse or the Rock Ptarmigan because it lives exclusively in the forest!
    But it is as important as the others from a biological and scientific point of view: it is an indicator species of environmental changes. Its specific demands in terms of vegetation and diversity of tree species ask for an adapted forest management. Bad preservation management of this habitats is one of the main causes of regression of the species.
  • Fauna

    The whistled language of groundhogs

    Groundhog is the favorite meal of the Golden Eagle and an important item in a fox diet.
    Always vigilant, standing up, it surveys its environment to avoid to be caught. Thanks to a very wide field of vision, and excellent hearing and smell abilities, nothing goes unnoticed. In case of alert, it warns the others with an alarm call: very high-pitched and brief for a danger coming from the sky, whistled and repeated for a danger on the ground. And that danger may be you!
  • Flora

    The Mountain Ash

    It is a small tree growing in forest edges. Its fruits are red orange berries loved by thrushes and blackbirds.
    The fruits can be used to make to make brandy, jelly or jam. But be aware that they are toxic at maturity, so you have to pick them earlier!
    In the nature reserve, the Mountain Ash is part of a participatory science program intended to measure the impact of climate change on the ecosystems of the mountain.
  • The 'Ayères'

    Originally, the word "Ahier" comes from a roman patois meaning Sycamore Maple. The words "pierrières" and "roc" are references to the numerous boulders, evidence of the landslides of Dérochoir, including the one in 1751 which killed 6 people and a few domestic animals. All these cabins were alpine cabins for agricultural use. They are now used as holiday cottages.
  • Livestock guardian dogs

    These are livestock guardian dogs, their presence is allowed in nature reserves. They defend sheep and ewes from larger predator attacks, such as wolfs. Often large sized dogs, qualified as "molossoid", they spend their lives protecting herds to which they are very attached.

    When approaching the herd, it’s very important to observe carefully the dog’s behavior and to take it in account while respecting the following instructions:
    - Stay away from the herd (bypass it if possible) - Announce your presence by speaking out loud to avoid surprising the herd and dogs
    - Keep calm and avoid sudden movements, keep walking without running. Talk gently to the dogs so that they get used to your presence and accept it.
    - Avoid looking straight into the dog’s eyes and hold an object between you and the dog.
  • Fauna

    The wolf

    The wolf made his return in France, on its own, since the 90’s. Coming from Italy, the species first colonized the southern Alps, then the whole alpine region.

    Since the summer of 2019, there is evidence of its presence in some of the nature reserves of Haute-Savoie, which explains the presence of livestock guardian dogs watching over several herds.

    Indeed, the wolf is carnivorous. It feeds mainly on wild animals such as Chamois or Roe Deer. But it can also consume ewes or sheep, especially from unprotected herds.

    So in order not to interfere with the work of the dogs, please follow the instructions!
  • Flora

    The Great yellow Gentian

    This large perennial plant, more than 1m high, is found in meadows, moors or forest clearings of the mountain and subalpine levels.
    Used in phytotherapy, it should not be confused with the highly toxic False Helleborine – also called White Hellebore-, next to which it grows and which looks very similar!
    Only the flowers are not alike, those of the Gentian are yellow. When not flowering, you can use the leaves to distinguish both species: Gentian is opposite-leaved, while the leaves of the False helleborine borne along the stem alternately (alternate-leaved plant).
  • Fauna

    The Alpine Ibex

    This protected species almost disappeared from the Alps at the end of the 19th century, mainly due to hunting or poaching.
    Various successive reintroductions in the entire Alps region have made it possible to increase the numbers of the populations although the stability of these populations is still threatened.
    In the nature reserves of Haute-Savoie, Ibexes are included in the monitored species and research programs intended to study its health conditions or to improve the management of its populations
  • Fauna

    The Bearded Vulture

    A wingspan of almost 3 meters, a bright orange body, a red circled eye, black feathers on either side of its beak forming a goatee, were enough to scare the alpine populations who considered the Bearded Vulture as the incarnation of the devil!
    Exterminated from the Alps at the beginning of the 20th century, this harmless and majestic bird is back in the alpine skies thanks to the largest animal reintroduction program initiated 30 years ago in Europe.
  • Lake

    The "laouchets" of Pormenaz

    These small, shallow bodies of water are mistakenly called lakes.
    Locally they are called "laouchets", which means "small bodies of water". Shallow, these bodies of water are home to a rare and protected species, the Sparganium or Narrowleaf Bur-reed, as well as to significant biodiversity. Eventually, these “laouchets” will fill in and become peat bogs.
  • Flora

    The Narrowleaf Bur-reed

    What you see on the surface of Laouchet is not an algae but a flowering plant with long narrow leaves, like ribbons with changing reflections, that float on the water. The Narrowleaf Bur-reed grows in calm, cold and shallow waters of mountain lakes and ponds. It has, below the surface, stems filled with nutritive reserves called rhizomes. With the natural filling process of Laouchet, the Narrowleaf Bur-reed spreads, intensifying the process by the accumulation of its wilted stems and leaves each winter.
  • Bogs

    Probably small bodies of water in a distant past. In this place, the filling-in of these former small water bodies created a bog. Archaeological excavations on its perimeter revealed evidence of human occupation dating back to the Bronze Age (-2200 years BC), the Iron Age (-800 years BC) and Antiquity (-52 years BC). It is thanks to the human made fires and their carbon 14 dating that we have been able to go back in time.
  • The mines of Pormenaz

    The mountain of Pormenaz is hosting several mines which were exploited from Gallo-Roman times until the 12th century. Argentiferous lead, auriferous and copper pyrites and antimony were extracted from these mines. It was mainly lead and silver that were sought after. About 125 kg of lead and 1 kg of silver were extracted from one ton of ore.
  • Fauna

    Encounter with a wild animal, what to do?

    During the harsh winter conditions, animals have no other choice than trying to survive day after day. Our presence on their territory will obviously disturb them, and even frighten them; so let's try to minimize this disturbance:
    • Stop and wait quietly untill the animal goes away.
    • Do not shout or make sudden movements which would stress the animal even more.
    • Do not try to approach it nor follow it.
  • Fauna


    Odonates, more commonly known as dragonflies, are insects.
    There are two stages in their lifecycle: a "larva" (or nymph) stage which is aquatic followed by a terrestrial stage, when the adults are grown to adults.
    Dragonflies are predators: they are carnivores that feed on different types of prey depending on their stage. They eat other insects as well.
    Their distribution is strongly linked to climate conditions and any change has a strong impact on their presence. Destruction of their wetland habitats is one of the main threats to dragonflies.
  • Fauna

    The Common Minnow and the Common Chub

    Minnows are very common in highly oxygenated waters. Its presence in high altitude lakes is due to trout fishing activities. Used as bait by fishermen, it colonized these mountain lakes.

    The Chub is a rather large fish, very widespread in France. It is an omnivore, which means that it eats everything. In many European countries, especially in the east, it is of highly culinary interest.
  • The history of Plaine-Joux

    From forest to mountain pasture, Plaine-Joux has not always been a ski resort as reflected in its name, which would mean "forest on a flat space".

    As early as the 1930’s, the inhabitants of Passy were already practicing ski activities in this location enjoying a magnificent panorama. It was around 1965 that it officially became a communal ski resort. Even nowadays, Plaine-Joux remains, as well in summer as in winter, a popular family resort for skiing, hiking, paragliding... and contemplation.
  • Fauna

    The placid Ibex

    The Ibex is not very shy, especially compared to the Chamois sharing its territory.
    Unlike most other mountain species, it remains at altitude even when winter and snow arrive.
    It then reaches ridges and snow-cleared areas where it will more easily find grass to feed on. This search for food costs a lot of energy. So, if you see it, do not approach and let it leave quietly in order to avoid wasting its precious energy, especially in winter.


Departure in front of Maison de la Réserve naturelle de Passy.
  1. Take the paved road which passes in front of the restaurant "Lou Pacheran" in the direction of the refuge of Moëde-Anterne, Col and Lac d'Anterne.
  2. Take the track up to the refuge of Moëde-Anterne, Col and Lac d'Anterne. Beacon 102.
  3. At the orientation table, continue on the track to the refuge of Moëde-Anterne, Col and Lac d'Anterne. Beacon 103.
  4. Continue on the track to the refuge of Moëde-Anterne, Col et Lac d'Anterne.
  5. Continue on the track to Ayères des Pierrières, Col and Lac d'Anterne. Beacon 16.
  6. Cross the hamlet of Ayères des Pierrières.
  7. Take the track on the left to the refuge of Moëde-Anterne, Col and Lac d'Anterne. Beacon 121.
  8. At the basin, either stay on the track that goes up to the left, or take the track straight ahead (pedestrian shortcut). Caution, aerial trail! Beacon 134.
  9. Stay on the track to the refuge of Moëde-Anterne, Col d'Anterne. Beacon 123.
  10. Stay on the track to the refuge of Moëde-Anterne, Lac de Pormenaz.
  11. At the refuge, take the track to Lac de Pormenaz. Beacon 124.
  12. Take the track in front of you to Lac de Pormenaz. Beacon 126.
  13. Take the track on the left to Lac de Pormenaz.
  14. Follow the same track to the Moëde-Anterne refuge.
  15. Take the track on the left to the chalets of Souay, Plaine-Joux. Caution: aireal trail! Otherwise return to the refuge and follow the up going route. Beacon 99.
  16. Continue to go down in the direction of the chalets of Souay, Plaine-Joux. Beacon 98.
  17. Pass between the two chalets and take the track on the left to the Châtelet d'Ayères refuge, Lac Vert. Beacon 97.
  18. Stay on the track to the Châtelet d'Ayères refuge, Lac Vert. Beacon 162.
  19. Go past the Châtelet d'Ayères refuge. Beacon 161.
  20. Take the track on the left to Lac Vert, Plaine-Joux. Beacon 95.
  21. Stay on the track to Lac Vert, Plaine-Joux. Beacon 160.
  22. Take the paved road after crossing the car park to Plaine-Joux. Beacon 159.
  23. Leave the paved road by taking the trail on the left, direction Plaine-Joux. Beacon 93.
  24. Take the path on the right, direction Plaine-Joux. Treehouses.
  25. Take the paved road on the left to Plaine-Joux.
  • Departure : Maison de la Réserve naturelle de Passy
  • Arrival : Maison de la Réserve naturelle de Passy
  • Towns crossed : Passy and Servoz

Altimetric profile


The trail les Argentières has aerial passages on the way back.

An alternative trail to go back down is possible.


Bus SAT Mont-Blanc L85

Access and parking

Access the Passy Plaine-Joux resort by road D43.
Parking at the entrance of the station.
Bus line L85 (SAT Mont-Blanc).

Parking :

Plaine Joux

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