渡良瀬貯水池
渡良瀬貯水池 in Tochigi, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 0.6 m visibility. Phosphorus: 100 µg/L.
- Clarity
- 0.6 m
Why 渡良瀬貯水池 has no A–F grade
渡良瀬貯水池 in Japan 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 and phosphorus, but not 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: the Ministry of the Environment (Japan).
渡良瀬貯水池 is a lake in Tochigi County, Japan.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-03-15. 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 渡良瀬貯水池
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 2 ft of visibility. Phosphorus level: 100 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.6 m | Not graded |
| Phosphorus | 100 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near 渡良瀬貯水池
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Fishing 渡良瀬貯水池
Frequently asked questions about 渡良瀬貯水池
What is the water quality of 渡良瀬貯水池?
- 渡良瀬貯水池 in Tochigi, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 0.6 m visibility. Phosphorus: 100 µg/L.
Is 渡良瀬貯水池 safe to swim in?
- 渡良瀬貯水池 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
45 measurements from 1 monitoring station, 2016–2025. Retrieved from Japan MOE public water-body monitoring (not the EPA Water Quality Portal) on 2026-08-16.
Collected and reported by
- Ministry of the Environment (Japan)
moe-jp45 samples · 2016–2025
Analytical methods
- MOE public water body monitoring (kosui, lakes)
Monitoring station identifiers (1)
0920201
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: 2025-03-15
Monitoring stations: 1