Grand Lac Long
Maskinongé, QuébecView mapDirections
This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade. See every year
Grand Lac Long in Maskinongé, Québec is classified classe oligotrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 6.3 m visibility. Phosphorus: 3.4 µg/L. Chlorophyll-a (algae): 1.4 µg/L.
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Grand Lac Long is a lake in Maskinongé County, Québec.
Source: Québec RSVL (MELCCFP) — not the EPA Water Quality Portal, last sampled 2025-08-01. Grade methodology: LakeQuality methodology.
What Grand Lac Long is good for
From access and monitoring records, not editorial picks.
- Clear water20.7 ft of visibility
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Grand Lac Long 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 Grand Lac Long
These are the measurements MELCCFP publishes for Grand Lac Long, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 20.7 ft down. Phosphorus 3.4 µg/L. Chlorophyll-a 1.4 µg/L.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.3 m | Measured, not scored |
| Phosphorus | 3.4 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | 1.4 µg/L | Measured, not scored |
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Frequently asked questions about Grand Lac Long
Ask about Grand Lac Long
Answers come straight from the public measurements and survey records on this page.
Where is Grand Lac Long?
- Grand Lac Long is a lake in Maskinongé, Québec. MELCCFP classifies it classe oligotrophe for 2025. This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.
What is the water quality of Grand Lac Long?
- Grand Lac Long in Maskinongé, Québec is classified classe oligotrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 6.3 m visibility. Phosphorus: 3.4 µg/L. Chlorophyll-a (algae): 1.4 µg/L.
Is Grand Lac Long 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 Grand Lac Long. 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 (18 classified 2014–2025)
| Year | Published class |
|---|---|
| 2024 | zone de transition oligo-mésotrophe |
| 2023 | zone de transition oligo-mésotrophe |
| 2022 | classe oligotrophe |
| 2021 | classe oligotrophe |
| 2020 | classe oligotrophe |
| 2019 | zone de transition oligo-mésotrophe |
| 2018 | classe oligotrophe |
| 2017 | zone de transition oligo-mésotrophe |
| 2016 | classe oligotrophe |
| 2015 | zone de transition oligo-mésotrophe |
| 2014 | zone de transition oligo-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 Grand Lac Long 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.