Jero Lake is a lake in Lieksa, Finland. This page reports official water-quality measurements, shown as reported.

Is Jero Lake safe to swim in?

Jero 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 Jero Lake?

Jero Lake has a maximum depth of 88.6 feet.

Jero Lake

Lieksa, FinlandView map Directions

Syke publishes the water-quality measurements for Jero Lake. Here is what has been measured.

Clarity

4.2 m

Clearer than most

Secchi · sampled 2025

Phosphorus

3.7 µg/L

Less phosphorus than most

Measured by Syke

Chlorophyll-a

2.9 µg/L

Less algae than most

Measured by Syke

Max depth

27 m

Bathymetric survey

89 ft max depth
Limited data

See the measurements Directions Where to stay

Jero Lake in Lieksa, Finland has official water-quality measurements, shown as reported. Water clarity: 4.2 m visibility. Phosphorus: 3.7 µg/L. Chlorophyll-a (algae): 2.9 µg/L. Maximum depth: 88.6 ft.

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How Jero Lake is classified

Jero Lake in Finland is published with the authority's own measurements and class. The measurements here are published by the agency that samples the lake, as reported. Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).

LakeQuality publishes no grade of its own beside it. Everything below thathas been measured is reported on this page.

Monitoring: the Finnish Environment Institute (Syke) and the ELY Centres.

Jero Lake is a lake in Lieksa County, Finland with a maximum depth of 89 feet.

Source: the Finnish Environment Institute (Syke) and the ELY Centres — not the EPA Water Quality Portal, last sampled 2025-09-01. Methodology: how these readings are compared.

What Jero Lake is good for

From access and monitoring records, not editorial picks.

Clear water13.9 ft of visibility
Deep water88.6 ft surveyed max depth

Swimming conditions

No reading

Limited data

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

Whether Jero Lake is safe to swim in today is a call for the Finnish Environment Institute (Syke) and the ELY Centres and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.

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Water quality measurements for Jero Lake

These are the measurements Syke publishes for Jero Lake. More on the source.

Good clarity, visible to about 13.9 ft. Phosphorus 3.7 µg/L. Chlorophyll-a 2.9 µg/L. TSI 34.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	4.22m	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	3.7µg/L	Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential.
Chlorophyll-a (algae)	2.9µg/L	Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water.
Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a.	34	Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Low nutrients, clear water. No reading is a swimming clearance.

Ask about Jero Lake

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

Lake Details

Max depth

27 m

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Stays near Jero Lake

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Fishing Jero Lake

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

Frequently asked questions about Jero Lake

Where is Jero Lake?: Jero Lake is a lake in Lieksa, Finland. This page reports official water-quality measurements, shown as reported.
What is the water quality of Jero Lake?: Jero Lake in Lieksa, Finland has official water-quality measurements, shown as reported. Water clarity: 4.2 m visibility. Phosphorus: 3.7 µg/L. Chlorophyll-a (algae): 2.9 µg/L. Maximum depth: 88.6 ft.
Is Jero Lake safe to swim in?: Jero 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 Jero Lake?: Jero Lake has a maximum depth of 88.6 feet.

Explore Jero Lake across LakeQuality

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Where this data comes from

31 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 Centressyke-vesla31 samples · 2016–2025

Analytical methods

SYKE VESLA

Monitoring station identifiers (1)

23063

Authority classifications are shown as the authority published them. See where the data comes from and data sources.