Hallwilersee
Hallwilersee in Aargau, Switzerland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 4.4 m visibility.
- Clarity
- 4.4 m
Why Hallwilersee has no A–F grade
Hallwilersee in Switzerland 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, but not 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: Eawag (the Swiss Federal Institute of Aquatic Science and Technology) and cantonal lake-monitoring programmes.
Hallwilersee is a lake in Aargau County, Switzerland.
Source: Eawag (the Swiss Federal Institute of Aquatic Science and Technology) and cantonal lake-monitoring programmes — not the EPA Water Quality Portal, last sampled 2023-12-18. Grade methodology: LakeGrade methodology.
Watch Hallwilersee water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Hallwilersee
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 14.4 ft. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.4 m | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Hallwilersee
Compare lakeside cabins, hotels, and vacation rentals near Hallwilersee in Aargau, Switzerland — 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 Hallwilersee
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Fishing Hallwilersee
Frequently asked questions about Hallwilersee
What is the water quality of Hallwilersee?
- Hallwilersee in Aargau, Switzerland has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 4.4 m visibility.
Is Hallwilersee safe to swim in?
- Hallwilersee 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.
Explore Hallwilersee across LakeGrade
More lakes in Switzerland
Where this data comes from
95 measurements from 1 monitoring station, 2016–2023. Retrieved from the listed programme (not the EPA Water Quality Portal). See data sources on 2026-08-20.
Collected and reported by
- Eawag
eawag-ch95 samples · —
Analytical methods
- Eawag long-term Swiss lake monitoring
Monitoring station identifiers (1)
LakeHallwil
Authority classifications are stored separately from LakeQuality A–F letters and are never blended. See how grades are calculated and data sources.