Retenue du Graon
Retenue du Graon in Vendée, France has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 1.4 m visibility. Phosphorus: 35 µg/L. Chlorophyll-a (algae): 17.6 µg/L.
- Clarity
- 1.4 m
Why Retenue du Graon has no A–F grade
Retenue du Graon in France is published with the authority's own measurements, not a LakeQuality letter. official authority class; not a LakeQuality A–F letter Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
A letter on the LakeQuality scale would be an invention, not an official class. Everything below that has been measured is still reported on this page.
Monitoring: the French water agencies, via UNEP GEMS/Water.
Retenue du Graon is a lake in Vendée County, France.
Source: the French water agencies, via UNEP GEMS/Water — not the EPA Water Quality Portal, last sampled 2023-10-02. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Retenue du Graon
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 4.6 ft. Phosphorus level: 35 µg/L. Chlorophyll-a: 17.6 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.4 m | Not graded |
| Phosphorus | 35 µg/L | Not graded |
| Chlorophyll-a (Algae) | 17.6 µg/L | Not graded |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Retenue du Graon
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Fishing Retenue du Graon
Frequently asked questions about Retenue du Graon
What is the water quality of Retenue du Graon?
- Retenue du Graon in Vendée, France has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 1.4 m visibility. Phosphorus: 35 µg/L. Chlorophyll-a (algae): 17.6 µg/L.
Is Retenue du Graon safe to swim in?
- Retenue du Graon has official nutrient and clarity measurements, not a bacteria swim class and not a safety clearance. Algal blooms, currents, and depth are not covered. Always check local notices before swimming.
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Where this data comes from
32 measurements from 1 monitoring station, 2017–2023. Retrieved from UNEP GEMS/Water GFQA (not the EPA Water Quality Portal) on 2026-08-20.
Collected and reported by
- Office français de la biodiversité (Hub'Eau)
hubeau-fr32 samples · —
Analytical methods
- Hub'Eau / Naïades plans d'eau
Monitoring station identifiers (1)
N350510
Authority classifications are stored separately from LakeQuality A–F letters and are never blended. See how grades are calculated and data sources.