Frontenac County, Ontario · Water Quality Report Card
Little Long Lake
Little Long Lake in Frontenac, Ontario received a water quality grade of A (Excellent). Water clarity: 4.6 m visibility. Phosphorus: 9.7 µg/L.
- Clarity
- 4.6 m
- Type
- Oligotrophic
Little Long Lake is a cold, clear oligotrophic lake in Frontenac County, Ontario. Water quality is graded A based on 2 sampling years through 2025. Compared to the 106 other monitored lakes in Frontenac County, Little Long Lake ranks #23 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-09-14. Grade methodology: LakeGrade methodology.
Watch Little Long Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 14.9 ft down. Phosphorus level: 9.7 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.55 m | A |
| Phosphorus | 9.7 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Little Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Long Lake in Frontenac, Ontario — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Little Long Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Little Long Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Little Long Lake — straight to your inbox. No spam, unsubscribe anytime.
Fishing Little Long Lake
Location
County Ranking
Ranked #23 of 107 lakes in Frontenac
Nearby Lakes in Frontenac
Explore Little Long Lake across LakeGrade
More Ontario Lake Rankings
Other Grade A Lakes in Ontario
Oligotrophic Lakes in Ontario
More records, surveys & data sources
Where this data comes from
Measurements for Little Long 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: 2025-09-14
Monitoring stations: