Grand Lac Sec
Lac-Saint-Jean-Est, QuébecView mapDirections
This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade. See every year
- 27 ft max depth
Grand Lac Sec in Lac-Saint-Jean-Est, Québec is classified classe eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.7 m visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 3.8 µg/L.
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Grand Lac Sec is a lake in Lac-Saint-Jean-Est County, Québec with an estimated average depth of about 27 feet.
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 Grand Lac Sec 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 Sec
These are the measurements MELCCFP publishes for Grand Lac Sec, 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 8.7 ft. Phosphorus 13 µg/L. Chlorophyll-a 3.8 µg/L.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.65 m | Measured, not scored |
| Phosphorus | 13 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | 3.8 µg/L | Measured, not scored |
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~8.2 m est. |
| Average Depth | ~3.4 m est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Québec has not published bathymetry for Grand Lac Sec.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
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Frequently asked questions about Grand Lac Sec
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Answers come straight from the public measurements and survey records on this page.
Where is Grand Lac Sec?
- Grand Lac Sec is a lake in Lac-Saint-Jean-Est, Québec. MELCCFP classifies it classe eutrophe for 2025. This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.
What is the water quality of Grand Lac Sec?
- Grand Lac Sec in Lac-Saint-Jean-Est, Québec is classified classe eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 2.7 m visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 3.8 µg/L.
Is Grand Lac Sec safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Grand Lac Sec?
- No published bathymetric survey covers Grand Lac Sec, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 27 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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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 Sec. 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 (2 classified 2024–2025)
| Year | Published class |
|---|---|
| 2024 | 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 Grand Lac Sec 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.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)