下久保ダム貯水池
下久保ダム貯水池 in Gunma, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 3 m visibility. Phosphorus: 14 µg/L.
- Clarity
- 3 m
Why 下久保ダム貯水池 has no A–F grade
下久保ダム貯水池 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).
下久保ダム貯水池 is a lake in Gunma 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 下久保ダム貯水池
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 9.7 ft. Phosphorus level: 14 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.95 m | Not graded |
| Phosphorus | 14 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near 下久保ダム貯水池
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Fishing 下久保ダム貯水池
Frequently asked questions about 下久保ダム貯水池
What is the water quality of 下久保ダム貯水池?
- 下久保ダム貯水池 in Gunma, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 3 m visibility. Phosphorus: 14 µg/L.
Is 下久保ダム貯水池 safe to swim in?
- 下久保ダム貯水池 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)
1020230
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