France · Morbihan
Lac Au Duc water quality
Is it clean? Yes — the water is officially clean
Lac Au Duc's official 2025 EU Bathing Water rating is Excellent — the highest official classification under the EU bathing-water assessment. 7 of the 11 classified seasons on record have rated Excellent or Good.
11-year classification history
Official EEA classification, one rating per bathing season, 2015–2025 — real data reported by national authorities.
- 2015: Sufficient2015
- 2016: Sufficient2016
- 2017: Sufficient2017
- 2018: Sufficient2018
- 2019: Good2019
- 2020: Good2020
- 2021: Good2021
- 2022: Excellent2022
- 2023: Excellent2023
- 2024: Excellent2024
- 2025: Excellent2025
Excellent in the most recent season, and 7 of 11 classified years rated Excellent or Good.
- Excellent
- Good
- Sufficient
- Poor
- Not classified
View as table
| Year | Classification |
|---|---|
| 2015 | Sufficient |
| 2016 | Sufficient |
| 2017 | Sufficient |
| 2018 | Sufficient |
| 2019 | Good |
| 2020 | Good |
| 2021 | Good |
| 2022 | Excellent |
| 2023 | Excellent |
| 2024 | Excellent |
| 2025 | Excellent |
- 2015Sufficient — meets the minimum EU standard in the latest annual assessment.
- 2016Sufficient — meets the minimum EU standard in the latest annual assessment.
- 2017Sufficient — meets the minimum EU standard in the latest annual assessment.
- 2018Sufficient — meets the minimum EU standard in the latest annual assessment.
- 2019Good — meets the EU bathing-water standard in the latest annual assessment.
- 2020Good — meets the EU bathing-water standard in the latest annual assessment.
- 2021Good — meets the EU bathing-water standard in the latest annual assessment.
- 2022Excellent — the highest official classification under the EU bathing-water assessment.
- 2023Excellent — the highest official classification under the EU bathing-water assessment.
- 2024Excellent — the highest official classification under the EU bathing-water assessment.
- 2025Excellent — the highest official classification under the EU bathing-water assessment.
2026 in-season sample timeline
No individual in-season sample feed has been published for Lac Au Duc yet. The official 2025 classification above, from the annual EU Bathing Water report, is the most current rating available for this beach.
How measurement works
Under the EU Bathing Water Directive, national authorities take water samples through the bathing season and test them for two indicator bacteria: intestinal enterococci and E. coli. Higher counts of either indicate a greater risk of contamination from sewage or agricultural runoff.
At the end of each season, the full set of results is reported to the European Environment Agency, which assigns one of four classifications — Excellent, Good, Sufficient or Poor — based on the statistical spread of the last four seasons' samples, not a single reading. That's why the rating published in spring 2026 covers the 2025 season, and why one bad sample doesn't necessarily change the rating on its own.
Official bathing water profile ↗ · ← Back to the Lac Au Duc overview · Sea temperature at Lac Au Duc →
Frequently asked questions
Is Lac Au Duc safe to swim in?
Generally, yes: the 2025 EU Bathing Water rating here is Excellent, backed by 7 of 11 classified seasons rating Excellent or Good. That applies to the water around Morbihan.
How is bathing water quality measured?
Water samples taken through the bathing season are tested for two indicator bacteria — intestinal enterococci and E. coli — with the full season's results reported to the European Environment Agency the following spring, which grades the season Excellent, Good, Sufficient or Poor under the EU Bathing Water Directive. Some national authorities, including Croatia's IZOR, also publish individual in-season samples ahead of that annual report; that isn't yet available for Lac Au Duc.
How often is the water tested?
Testing happens throughout the season (typically 4+ samples, May–September), but the resulting classification is only published once, the following spring. Lac Au Duc doesn't yet have a published in-season feed, so the annual rating above is the most current figure on hand.