Etang de la Grosse Pierre
Etang de la Grosse Pierre in Yvelines, France has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 0.9 m visibility. Chlorophyll-a (algae): 42 µg/L.
- Clarity
- 0.9 m
Why Etang de la Grosse Pierre has no A–F grade
Etang de la Grosse Pierre 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 and algae (chlorophyll-a), but not phosphorus.
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.
Etang de la Grosse Pierre is a lake in Yvelines County, France.
Source: the French water agencies, via UNEP GEMS/Water — not the EPA Water Quality Portal, last sampled 2022-09-20. 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 Etang de la Grosse Pierre
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 3 ft of visibility. Chlorophyll-a: 42 µg/L. Trophic State Index: 64.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.9 m | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 42 µg/L | Not graded |
| Trophic State Index (TSI) | 64 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Etang de la Grosse Pierre
Compare lakeside cabins, hotels, and vacation rentals near Etang de la Grosse Pierre in Yvelines, France — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Fishing Etang de la Grosse Pierre
Frequently asked questions about Etang de la Grosse Pierre
What is the water quality of Etang de la Grosse Pierre?
- Etang de la Grosse Pierre in Yvelines, France has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 0.9 m visibility. Chlorophyll-a (algae): 42 µg/L.
Is Etang de la Grosse Pierre safe to swim in?
- Etang de la Grosse Pierre 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.
Explore Etang de la Grosse Pierre across LakeGrade
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Where this data comes from
8 measurements from 1 monitoring station, 2022. 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-fr8 samples · —
Analytical methods
- Hub'Eau / Naïades plans d'eau
Monitoring station identifiers (1)
H3009523
Authority classifications are stored separately from LakeQuality A–F letters and are never blended. See how grades are calculated and data sources.