Sonnanen Lake
Sonnanen Lake in Heinola, Finland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 9.4 m visibility. Phosphorus: 3 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Maximum depth: 45.3 ft.
- Clarity
- 9.4 m
- Max depth
- 13.8 m
Why Sonnanen Lake has no A–F grade
Sonnanen Lake in Finland is published with the authority's own measurements, not a LakeQuality letter. official authority class; not a LakeQuality A–F letter Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
A letter on the LakeQuality scale would be an invention, not an official class. Everything below that has been measured is still reported on this page.
Monitoring: the Finnish Environment Institute (Syke) and the ELY Centres.
Sonnanen Lake is a lake in Heinola County, Finland with a maximum depth of 45 feet.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-05-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Sonnanen Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Crystal clear, you can see 30.8 ft down. Phosphorus level: 3 µg/L. Chlorophyll-a: 1.3 µg/L. Trophic State Index: 27.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.4 m | Not graded |
| Phosphorus | 3 µg/L | Not graded |
| Chlorophyll-a (Algae) | 1.3 µg/L | Not graded |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 13.8 m |
Where to stay near Sonnanen Lake
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Fishing Sonnanen Lake
Frequently asked questions about Sonnanen Lake
What is the water quality of Sonnanen Lake?
- Sonnanen Lake in Heinola, Finland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 9.4 m visibility. Phosphorus: 3 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Maximum depth: 45.3 ft.
Is Sonnanen Lake safe to swim in?
- Sonnanen Lake has official nutrient and clarity measurements, not a bacteria swim class and not a safety clearance. Algal blooms, currents, and depth are not covered. Always check local notices before swimming.
How deep is Sonnanen Lake?
- Sonnanen Lake has a maximum depth of 45.3 feet.
Explore Sonnanen Lake across LakeGrade
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Where this data comes from
113 measurements from 1 monitoring station, 2016–2026. Retrieved from Syke VESLA (not the EPA Water Quality Portal) on 2026-08-16.
Collected and reported by
- Finnish Environment Institute (Syke) and ELY Centres
syke-vesla113 samples · 2016–2026
Analytical methods
- SYKE VESLA
Monitoring station identifiers (1)
14538
Authority classifications are stored separately from LakeQuality A–F letters and are never blended. See methodology and data sources.
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: 2026-05-18
Monitoring stations: 1