Black River Confluence Lake
Black River Confluence Lake in Sullivan County, New Hampshire has a water quality grade of B (Good). Phosphorus: 14.2 µg/L.
- Type
- Mesotrophic
- Public access
- Yes
Black River Confluence Lake is a mesotrophic lake in Sullivan County, New Hampshire. Water quality is graded B based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 23 other monitored lakes in Sullivan County, Black River Confluence Lake ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2022-07-31. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
No clarity data. Phosphorus level: 14.2 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 14.2 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Black River Confluence Lake
Compare lakeside cabins, hotels, and vacation rentals near Black River Confluence Lake in Sullivan County, New Hampshire — 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 Black River Confluence Lake
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Recreation & Access
- Charlestown Picnic AreaPublic
Named access points from the USGS National Boat Ramps inventory, snapped within 5 km. More lakes with boat ramps
Fishing Black River Confluence Lake
County Ranking
Ranked #14 of 24 lakes in Sullivan County
Nearby Lakes in Sullivan County
Frequently asked questions about Black River Confluence Lake
Where is Black River Confluence Lake?
- Black River Confluence Lake is a lake in Sullivan County, New Hampshire. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Black River Confluence Lake?
- Black River Confluence Lake in Sullivan County, New Hampshire has a water quality grade of B (Good). Phosphorus: 14.2 µg/L.
Is Black River Confluence Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Black River Confluence Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
Are there boat ramps on Black River Confluence Lake?
- Black River Confluence Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Charlestown Picnic Area. Public access is listed as yes.
Explore Black River Confluence Lake across LakeGrade
More New Hampshire Lake Rankings
Top 25 by overall water quality score
Top 25 by Secchi water clarity
Grade A/B + low algae filter
Panfish-rich, public access
Full state directory
Other Grade B Lakes in New Hampshire
Mesotrophic Lakes in New Hampshire
Where this data comes from
24 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330024 samples · 2021–2022
Analytical methods
- 4500 P H ~ Manual Digestion and Flow Injection Analysis for Total Phosphorus
- 4500 N C ~ Persufate Method for Total Nitrogen
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory