Grafham Water Reservoir
Grafham Water Reservoir in Cambs and Bedfordshire, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 236.5 µg/L. Chlorophyll-a (algae): 10.2 µg/L.
Why Grafham Water Reservoir has no A–F grade
Grafham Water Reservoir 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).
Grafham Water Reservoir is a lake in Cambs and Bedfordshire County, England.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-07-23. 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 Grafham Water Reservoir
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 236.5 µg/L. Chlorophyll-a: 10.2 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 236.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 10.2 µg/L | Not graded |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Grafham Water Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Grafham Water Reservoir in Cambs and Bedfordshire, 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.
Top-rated places to stay near Grafham Water Reservoir
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Fishing Grafham Water Reservoir
Frequently asked questions about Grafham Water Reservoir
What is the water quality of Grafham Water Reservoir?
- Grafham Water Reservoir in Cambs and Bedfordshire, England has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 236.5 µg/L. Chlorophyll-a (algae): 10.2 µg/L.
Is Grafham Water Reservoir safe to swim in?
- Grafham Water Reservoir 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 Grafham Water Reservoir across LakeGrade
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Where this data comes from
83 measurements from 1 monitoring station, 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-wqa83 samples · 2016–2026
Monitoring station identifiers (1)
AN-22M18A
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: 2026-07-23
Monitoring stations: 1