奈良俣ダム貯水池
奈良俣ダム貯水池 in Gunma, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 5.5 m visibility. Phosphorus: 4 µg/L.
- Clarity
- 5.5 m
Why 奈良俣ダム貯水池 has no A–F grade
奈良俣ダム貯水池 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).
奈良俣ダム貯水池 is a lake in Gunma County, Japan.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-12-15. 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 奈良俣ダム貯水池
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Crystal clear, you can see 17.9 ft down. Phosphorus level: 4 µg/L. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.45 m | Not graded |
| Phosphorus | 4 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near 奈良俣ダム貯水池
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Fishing 奈良俣ダム貯水池
Frequently asked questions about 奈良俣ダム貯水池
What is the water quality of 奈良俣ダム貯水池?
- 奈良俣ダム貯水池 in Gunma, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 5.5 m visibility. Phosphorus: 4 µg/L.
Is 奈良俣ダム貯水池 safe to swim in?
- 奈良俣ダム貯水池 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
33 measurements from 1 monitoring station, 2016–2024. 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-jp33 samples · 2016–2024
Analytical methods
- MOE public water body monitoring (kosui, lakes)
Monitoring station identifiers (1)
1020200
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: 2024-12-15
Monitoring stations: 1