Marsjön Lake
Marsjön Lake in Inkoo, Finland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 1.6 m visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 7.7 µg/L. Maximum depth: 29.9 ft.
- Clarity
- 1.6 m
- Max depth
- 9.1 m
Why Marsjön Lake has no A–F grade
Marsjön 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.
Marsjön Lake is a lake in Inkoo County, Finland with a maximum depth of 30 feet.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-10-30. 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 Marsjön Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 5.1 ft. Phosphorus level: 22 µg/L. Chlorophyll-a: 7.7 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.55 m | Not graded |
| Phosphorus | 22 µg/L | Not graded |
| Chlorophyll-a (Algae) | 7.7 µg/L | Not graded |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 9.1 m |
Where to stay near Marsjön Lake
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Fishing Marsjön Lake
Frequently asked questions about Marsjön Lake
What is the water quality of Marsjön Lake?
- Marsjön Lake in Inkoo, Finland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 1.6 m visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 7.7 µg/L. Maximum depth: 29.9 ft.
Is Marsjön Lake safe to swim in?
- Marsjön 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 Marsjön Lake?
- Marsjön Lake has a maximum depth of 29.9 feet.
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Where this data comes from
30 measurements from 1 monitoring station, 2016–2025. 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-vesla30 samples · 2016–2025
Analytical methods
- SYKE VESLA
Monitoring station identifiers (1)
82543
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: 2025-10-30
Monitoring stations: 1