Where is Iso-Herttu Lake?

Iso-Herttu Lake is a lake in Hankasalmi, Finland. This page reports official water-quality measurements, shown as reported.

Is Iso-Herttu Lake safe to swim in?

Iso-Herttu 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 Iso-Herttu Lake?

Iso-Herttu Lake has a maximum depth of 9.8 feet.

Iso-Herttu Lake

Hankasalmi, FinlandView map Directions

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

Clarity

0.8 m

Murkier than most

Secchi · sampled 2024

Phosphorus

34 µg/L

More phosphorus than most

Measured by Syke

Chlorophyll-a

33 µg/L

More algae than most

Measured by Syke

Max depth

3 m

Bathymetric survey

10 ft max depth
Limited data

See the measurements Directions Where to stay

Iso-Herttu Lake in Hankasalmi, Finland has official water-quality measurements, shown as reported. Water clarity: 0.8 m visibility. Phosphorus: 34 µg/L. Chlorophyll-a (algae): 33 µg/L. Maximum depth: 9.8 ft.

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How Iso-Herttu Lake is classified

Iso-Herttu 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.

Iso-Herttu Lake is a lake in Hankasalmi County, Finland with a maximum depth of 10 feet.

Source: the Finnish Environment Institute (Syke) and the ELY Centres — not the EPA Water Quality Portal, last sampled 2024-08-19. Methodology: how these readings are compared.

Swimming conditions

No reading

Limited data

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

Whether Iso-Herttu 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 Iso-Herttu Lake

These are the measurements Syke publishes for Iso-Herttu Lake. More on the source.

Very murky, less than 2.6 ft of visibility. Phosphorus 34 µg/L. Chlorophyll-a 33 µg/L. TSI 61.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	0.8m	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	34µg/L	Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential.
Chlorophyll-a (algae)	33µg/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.	61	Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic

High nutrients, frequent algae, reduced clarity

Ask about Iso-Herttu Lake

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

Lake Details

Max depth

3 m

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Fishing Iso-Herttu Lake

→ Iso-Herttu Lake fishing regulations (limits, seasons, special rules)

Frequently asked questions about Iso-Herttu Lake

Where is Iso-Herttu Lake?: Iso-Herttu Lake is a lake in Hankasalmi, Finland. This page reports official water-quality measurements, shown as reported.
What is the water quality of Iso-Herttu Lake?: Iso-Herttu Lake in Hankasalmi, Finland has official water-quality measurements, shown as reported. Water clarity: 0.8 m visibility. Phosphorus: 34 µg/L. Chlorophyll-a (algae): 33 µg/L. Maximum depth: 9.8 ft.
Is Iso-Herttu Lake safe to swim in?: Iso-Herttu 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 Iso-Herttu Lake?: Iso-Herttu Lake has a maximum depth of 9.8 feet.

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Where this data comes from

20 measurements from 1 monitoring station, 2016–2024. 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-vesla20 samples · 2016–2024

Analytical methods

SYKE VESLA

Monitoring station identifiers (1)

25320

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