Tarn Hows
Tarn Hows in Cumbria and Lancashire, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 6.5 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
Why Tarn Hows has no A–F grade
Tarn Hows in England 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 phosphorus and algae (chlorophyll-a), but not water clarity.
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 Environment Agency (England).
Tarn Hows is a lake in Cumbria and Lancashire County, England.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-07-09. 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 Tarn Hows
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 6.5 µg/L. Chlorophyll-a: 2.8 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 6.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 2.8 µg/L | Not graded |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Tarn Hows
Compare lakeside cabins, hotels, and vacation rentals near Tarn Hows in Cumbria and Lancashire, England — 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.
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Fishing Tarn Hows
Frequently asked questions about Tarn Hows
What is the water quality of Tarn Hows?
- Tarn Hows in Cumbria and Lancashire, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 6.5 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
Is Tarn Hows safe to swim in?
- Tarn Hows 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 Tarn Hows across LakeGrade
More lakes in England
Where this data comes from
58 measurements from 2 monitoring stations, 2016–2026. Retrieved from the Environment Agency (England; not the EPA Water Quality Portal) on 2026-08-16.
Collected and reported by
- Environment Agency (England)
ea-wqa58 samples · 2016–2026
Monitoring station identifiers (2)
NW-88022594NW-LSN0400
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: 2026-07-09
Monitoring stations: 2