北川ダム
北川ダム in Oita, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 3.5 m visibility. Phosphorus: 11 µg/L.
- Clarity
- 3.5 m
Why 北川ダム has no A–F grade
北川ダム 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).
北川ダム is a lake in Oita 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 北川ダム
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 11.5 ft. Phosphorus level: 11 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.5 m | Not graded |
| Phosphorus | 11 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near 北川ダム
Compare lakeside cabins, hotels, and vacation rentals near 北川ダム in Oita, Japan — 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.
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Fishing 北川ダム
Frequently asked questions about 北川ダム
What is the water quality of 北川ダム?
- 北川ダム in Oita, Japan has official water-quality measurements, not a LakeQuality A–F grade. Water clarity: 3.5 m visibility. Phosphorus: 11 µg/L.
Is 北川ダム safe to swim in?
- 北川ダム 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 北川ダム across LakeGrade
More lakes in Japan
Where this data comes from
63 measurements from 3 monitoring stations, 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-jp63 samples · 2016–2025
Analytical methods
- MOE public water body monitoring (kosui, lakes)
Monitoring station identifiers (3)
442001044200204420090
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: 3