Colne Mere
Colne Mere in Herts and North London, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 480 µg/L. Chlorophyll-a (algae): 7.9 µg/L.
Why Colne Mere has no A–F grade
Colne Mere 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).
Colne Mere is a lake in Herts and North London County, England.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-11-24. 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 Colne Mere
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 480 µg/L. Chlorophyll-a: 7.9 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 480 µg/L | Not graded |
| Chlorophyll-a (Algae) | 7.9 µg/L | Not graded |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Colne Mere
Compare lakeside cabins, hotels, and vacation rentals near Colne Mere in Herts and North London, 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 Colne Mere
Frequently asked questions about Colne Mere
What is the water quality of Colne Mere?
- Colne Mere in Herts and North London, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 480 µg/L. Chlorophyll-a (algae): 7.9 µg/L.
Is Colne Mere safe to swim in?
- Colne Mere 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 Colne Mere across LakeGrade
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Where this data comes from
6 measurements from 1 monitoring station, 2019–2021. Retrieved from the Environment Agency (England; not the EPA Water Quality Portal) on 2026-08-16.
Collected and reported by
- Environment Agency (England)
ea-wqa6 samples · 2019–2021
Monitoring station identifiers (1)
TH-PRTS0034
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: 2021-11-24
Monitoring stations: 1