Lac Duffy
Montcalm, QuébecView mapDirections
This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade. See every year
Lac Duffy in Montcalm, Québec is classified zone de transition oligo-mésotrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.8 m visibility. Phosphorus: 9.9 µg/L. Chlorophyll-a (algae): 3.8 µg/L.
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Lac Duffy is a lake in Montcalm County, Québec.
Source: Québec RSVL (MELCCFP) — not the EPA Water Quality Portal, last sampled 2025-08-01. Grade methodology: LakeQuality methodology.
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Lac Duffy is safe to swim in today is a call for le Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lac Duffy
These are the measurements MELCCFP publishes for Lac Duffy, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 9 ft. Phosphorus 9.9 µg/L. Chlorophyll-a 3.8 µg/L.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.75 m | Measured, not scored |
| Phosphorus | 9.9 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | 3.8 µg/L | Measured, not scored |
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Frequently asked questions about Lac Duffy
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Answers come straight from the public measurements and survey records on this page.
Where is Lac Duffy?
- Lac Duffy is a lake in Montcalm, Québec. MELCCFP classifies it zone de transition oligo-mésotrophe for 2025. This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.
What is the water quality of Lac Duffy?
- Lac Duffy in Montcalm, Québec is classified zone de transition oligo-mésotrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.8 m visibility. Phosphorus: 9.9 µg/L. Chlorophyll-a (algae): 3.8 µg/L.
Is Lac Duffy safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
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The authority’s own classification
Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) publishes its own classification for Lac Duffy. It is shown here as theirs, in their words, and is not folded into the LakeQuality letter.
This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.
A trophic class ranks how nutrient-rich a lake is, from oligotrophic at the low end to eutrophic at the high end. It describes nutrients and plant growth, not bacteria, and it is not a swimming clearance.
Earlier years (3 classified 2023–2025)
| Year | Published class |
|---|---|
| 2024 | classe mésotrophe |
| 2023 | classe mésotrophe |
Published by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec). A classification is not a same-day swimming clearance. See data sources.
Where this data comes from
Measurements for Lac Duffy come from the Réseau de surveillance volontaire des lacs (RSVL), not the EPA Water Quality Portal. Per-sample source details are not recorded for this lake. MELCCFP RSVL (CC BY 4.0). See data sources.