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LakeQuality

Lac Saint-Onge

La Haute-Côte-Nord, QuébecView mapDirections

classe hyper-eutrophe

This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade. See every year

Clarity
1.3 m
Secchi · sampled 2025
Phosphorus
15.3 µg/L
Measured by MELCCFP
Chlorophyll-a
5.2 µg/L
Measured by MELCCFP
Max depth
~12.2 m est.
GLOBathy model
  • 40 ft max depth

Lac Saint-Onge in La Haute-Côte-Nord, Québec is classified classe hyper-eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 1.3 m visibility. Phosphorus: 15.3 µg/L. Chlorophyll-a (algae): 5.2 µg/L.

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Lac Saint-Onge is a lake in La Haute-Côte-Nord County, Québec with an estimated average depth of about 40 feet.

Source: Québec RSVL (MELCCFP) — not the EPA Water Quality Portal, last sampled 2025-08-01. Grade methodology: LakeQuality methodology.

Swimming conditions

No reading

Not rated

Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.

Whether Lac Saint-Onge 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.

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Water quality measurements for Lac Saint-Onge

These are the measurements MELCCFP publishes for Lac Saint-Onge, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

Murky, only visible to about 4.3 ft. Phosphorus 15.3 µg/L. Chlorophyll-a 5.2 µg/L.

MetricValueEPA condition class
Water Clarity (Secchi Depth)1.3 mMeasured, not scored
Phosphorus15.3 µg/LMeasured, not scored
Chlorophyll-a (Algae)5.2 µg/LMeasured, not scored

Lake Details

CharacteristicValue
Maximum Depth~12.2 m est.
Average Depth~4.3 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 Lac Saint-Onge.

Lake Size & Watershed

Watershed (drainage) area
4 sq mi
Surface area
205 acres
Shoreline
4.3 mi
Elevation
348 ft

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.

Fishing Lac Saint-Onge

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Frequently asked questions about Lac Saint-Onge

Ask about Lac Saint-Onge

Answers come straight from the public measurements and survey records on this page.

Where is Lac Saint-Onge?

Lac Saint-Onge is a lake in La Haute-Côte-Nord, Québec. MELCCFP classifies it classe hyper-eutrophe for 2025. This is MELCCFP's own trophic classification for 2025, not a LakeQuality grade.

What is the water quality of Lac Saint-Onge?

Lac Saint-Onge in La Haute-Côte-Nord, Québec is classified classe hyper-eutrophe by Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (Québec) for 2025. Water clarity: 1.3 m visibility. Phosphorus: 15.3 µg/L. Chlorophyll-a (algae): 5.2 µg/L.

Is Lac Saint-Onge safe to swim in?

Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.

How deep is Lac Saint-Onge?

No published bathymetric survey covers Lac Saint-Onge, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 40 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.

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 Saint-Onge. It is shown here as theirs, in their words, and is not folded into the LakeQuality letter.

Most recent, 2025
classe hyper-eutrophe

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 (13 classified 2011–2025)
YearPublished class
2024classe eutrophe
2023zone de transition méso-eutrophe
2022zone de transition méso-eutrophe
2021classe eutrophe
2020classe hyper-eutrophe
2019classe eutrophe
2015classe eutrophe
2014zone de transition méso-eutrophe
2013zone de transition méso-eutrophe
2012classe hyper-eutrophe
2011classe hyper-eutrophe

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 Saint-Onge 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)