Is Onawa Lake safe to swim in?

Generally safe for swimming, moderate water quality. Onawa Lake has an overall water quality grade of C. Always check local health department advisories before swimming.

Muskoka District County, Ontario · Water Quality Report Card

Onawa Lake

Grade C — Fair

Eutrophic

Onawa Lake in Muskoka District, Ontario received a water quality grade of C (Fair). Water clarity: 0.7 m visibility. Phosphorus: 19.7 µg/L.

Clarity: 0.7 m
Type: Eutrophic

Where to stay →Safe to swim?

Onawa Lake is a productive, nutrient-rich eutrophic lake in Muskoka District County, Ontario. Water quality is graded C based on 2 sampling years through 2018. Compared to the 169 other monitored lakes in Muskoka District County, Onawa Lake ranks #164 for water quality.

Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2018-08-11. Grade methodology: LakeGrade methodology.

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Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Very murky, less than 2.3 ft of visibility. Phosphorus level: 19.7 µg/L. Trophic State Index: 56.

Metric	Value	Grade
Water Clarity (Secchi Depth)	0.7 m	F
Phosphorus	19.7 µg/L	A
Chlorophyll-a (Algae)	No data
Trophic State Index (TSI)	56	Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Onawa Lake

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Fishing Onawa Lake

→ Onawa Lake fishing regulations (limits, seasons, special rules)

Location

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County Ranking

Ranked #164 of 170 lakes in Muskoka District

Cleaner Lakes Within 30 Miles

Onawa Lake holds Grade C. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Muskoka District

Explore Onawa Lake across LakeGrade

Lake Fishing Forecast

Species activity outlook by water temperature and season

Eutrophic Lakes

High nutrients, frequent algae, reduced clarity

The State of Ontario's Lakes

Ontario's cleanest and most-polluted lakes, ranked

More Ontario Lake Rankings

Cleanest lakes in Ontario

Top 25 by overall water quality score

Clearest lakes in Ontario

Top 25 by Secchi water clarity

Best swimming lakes in Ontario

Grade A/B + low algae filter

Family fishing lakes in Ontario

Panfish-rich, public access

All Ontario lakes

Full state directory

Other Grade C Lakes in Ontario

Little Cornick Lake

Parry Sound District · 2.8 m

Lower Fletcher Lake

Haliburton · 2.7 m

Jewel Lake

Nipissing District · 2.6 m

Shelbourne Pond

Parry Sound District · 2.2 m

Saunders Lake

Nipissing District · 1.5 m

Manson Lake

Parry Sound District · 2.2 m

Eutrophic Lakes in Ontario

Foote Lake Cecebe Lake Crawford Lake Saunders Lake

More records, surveys & data sources

Where this data comes from

Measurements for Onawa Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.

Data Sources

Water quality data from the EPA Water Quality Portal

Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion

Most recent sample: 2018-08-11

Monitoring stations:

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