Clearest lakes in France
Clearest lakes in France: 307 named lakes have an official Secchi depth. The 20 below are ranked by that reading — water clarity, not a LakeQuality A–F grade.
Lake map
Highest Secchi readings in France
| Lake | Place | Total phosphorus | Chlorophyll-a | Secchi | Year |
|---|---|---|---|---|---|
| Lac Bleu | Hautes-Pyrénées | — | 1.0 µg/L | 15 m | 2022 |
| Lac de Migouélou | Hautes-Pyrénées | — | 1.0 µg/L | 12 m | 2022 |
| Lac de Caillauas | Hautes-Pyrénées | — | 1.0 µg/L | 11 m | 2020 |
| Lac de L'Oule | Hautes-Pyrénées | — | 1.0 µg/L | 11 m | 2020 |
| Etang de Soulcem | Ariège | — | 1.0 µg/L | 10 m | 2024 |
| Lac de Cap de Long | Hautes-Pyrénées | — | 1.0 µg/L | 9.8 m | 2024 |
| Etang de Naguilhes | Ariège | — | 1.0 µg/L | 9.3 m | 2023 |
| Lac D'Orédon | Hautes-Pyrénées | — | 1.0 µg/L | 8.9 m | 2023 |
| Lac de Servieres | Puy-de-Dôme | — | 1.2 µg/L | 8.4 m | 2022 |
| Lac D'Arjuzanx | Landes | 10 µg/L | 0.60 µg/L | 8.3 m | 2023 |
| Lac D'Aubert | Hautes-Pyrénées | — | 1.0 µg/L | 7.8 m | 2021 |
| Etang de Gnioure | Ariège | — | 1.0 µg/L | 7.7 m | 2024 |
| Lac du Bouchet | Haute-Loire | — | 1.2 µg/L | 7.2 m | 2023 |
| Lac de Tazenat | Puy-de-Dôme | 10 µg/L | 2.1 µg/L | 7.1 m | 2023 |
| Lac de Sède | Haute-Garonne | — | 1.5 µg/L | 5.8 m | 2022 |
| Le Lac de Kruth-Wildenstein | Haut-Rhin | — | 1.0 µg/L | 5.2 m | 2021 |
| Barrage-Réservoir Seine | Aube | — | 2.0 µg/L | 5.0 m | 2024 |
| Le Lac de Longemer | Vosges | — | 2.5 µg/L | 5.0 m | 2017 |
| Lac de Commanday | Landes | 10 µg/L | 0.60 µg/L | 5.0 m | 2020 |
| Lac D'Issarles | Ardèche | 10 µg/L | 6.0 µg/L | 4.9 m | 2025 |
Showing 20 of 307 named lakes. Open a county or place page for the rest.
Frequently asked questions
- Which lakes in France are the clearest?
- 307 named lakes in France have an official Secchi depth. This page ranks the 20 deepest readings. Secchi is a clarity measurement, not a swim-safety class and not a LakeQuality A–F grade.
- Is clear water the same as clean water?
- No. Secchi measures how far a disk stays visible. A clear lake can still have bacteria, toxins, or contaminants this catalog does not grade. Open a lake page for the authority's values.
Clearest lakes in other countries
Named lakes and official measurements
Directory of official lake water quality
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