Lac à la Tortue
Urban agglomeration of Longueuil, QuébecView mapDirections
This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade. See every year
Lac à la Tortue in Urban agglomeration of Longueuil, Québec is classified zone de transition méso-eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.2 m visibility. Phosphorus: 17.9 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
Lac à la Tortue is a lake in Urban agglomeration of Longueuil County, Québec.
Source: Québec RSVL (MELCCFP) — not the EPA Water Quality Portal, last sampled 2025-08-01. Methodology: how these readings are compared.
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Lac à la Tortue 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 à la Tortue
These are the measurements MELCCFP publishes for Lac à la Tortue, 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 7.2 ft. Phosphorus 17.9 µg/L. Chlorophyll-a 6.4 µg/L.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.2m | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 17.9µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 6.4µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
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Frequently asked questions about Lac à la Tortue
Where is Lac à la Tortue?
- Lac à la Tortue is a lake in Urban agglomeration of Longueuil, Québec. MELCCFP classifies it zone de transition méso-eutrophe for 2025. This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.
What is the water quality of Lac à la Tortue?
- Lac à la Tortue in Urban agglomeration of Longueuil, Québec is classified zone de transition méso-eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.2 m visibility. Phosphorus: 17.9 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
Is Lac à la Tortue 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 à la Tortue. 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 méso-eutrophe |
| 2023 | classe eutrophe |
| 2022 | classe eutrophe |
| 2021 | zone de transition méso-eutrophe |
| 2020 | classe mésotrophe |
| 2019 | classe mésotrophe |
| 2018 | zone de transition méso-eutrophe |
| 2017 | zone de transition méso-eutrophe |
| 2016 | zone de transition méso-eutrophe |
| 2015 | zone de transition méso-eutrophe |
| 2014 | 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 à la Tortue 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.