Lough Key
Lough Key in Roscommon, Ireland has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 4.2 µg/L.
Why Lough Key has no A–F grade
Lough Key in Ireland 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 Environmental Protection Agency of Ireland, via UNEP GEMS/Water, with WFD lake names from EPA Ireland.
Lough Key is a lake in Roscommon County, Ireland.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2022-10-20. 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 Lough Key
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 19 µg/L. Chlorophyll-a: 4.2 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 19 µg/L | Not graded |
| Chlorophyll-a (Algae) | 4.2 µg/L | Not graded |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lough Key
Compare lakeside cabins, hotels, and vacation rentals near Lough Key in Roscommon, Ireland — 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 Lough Key
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Fishing Lough Key
Frequently asked questions about Lough Key
What is the water quality of Lough Key?
- Lough Key in Roscommon, Ireland has official water-quality measurements, not a LakeQuality A–F grade. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 4.2 µg/L.
Is Lough Key safe to swim in?
- Lough Key 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.
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Where this data comes from
59 measurements from 5 monitoring stations, 2018–2022. Retrieved from UNEP GEMS/Water GFQA (not the EPA Water Quality Portal) on 2026-08-16.
Collected and reported by
- European Environment Agency
europeanenvironmentagenc59 samples · —
Analytical methods
- GEMStat OPEN / CC BY 4.0
- EPA Ireland WFD lake waterbodies CC BY 4.0
Monitoring station identifiers (5)
IRL00322IRL00323IRL00324IRL00325IRL00326
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: 2022-10-20
Monitoring stations: 5