Northwood Lake-Old Dump
Northwood Lake-Old Dump in Rockingham County, New Hampshire has a water quality grade of B (Good). Phosphorus: 12.4 µg/L.
- Type
- Mesotrophic
Northwood Lake-Old Dump is a mesotrophic lake in Rockingham County, New Hampshire. Water quality is graded B based on 1 sampling years through 2023. Compared to the 50 other monitored lakes in Rockingham County, Northwood Lake-Old Dump ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-09-28. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria advisory
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: 12.4 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 12.4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Northwood Lake-Old Dump
Compare lakeside cabins, hotels, and vacation rentals near Northwood Lake-Old Dump in Rockingham 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 Northwood Lake-Old Dump
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Fishing Northwood Lake-Old Dump
EPA Impairment Status
Northwood Lake-Old Dump is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700060502-08-02 · Official waterbody report · Matched by proximity (0.55 km)
County Ranking
Ranked #6 of 51 lakes in Rockingham County
Nearby Lakes in Rockingham County
Frequently asked questions about Northwood Lake-Old Dump
Where is Northwood Lake-Old Dump?
- Northwood Lake-Old Dump is a lake in Rockingham 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 Northwood Lake-Old Dump?
- Northwood Lake-Old Dump in Rockingham County, New Hampshire has a water quality grade of B (Good). Phosphorus: 12.4 µg/L.
Is Northwood Lake-Old Dump safe to swim in?
- Good for swimming, clear water with low algae levels. Northwood Lake-Old Dump has a water quality grade of B (Good). Always check local health department advisories before swimming.
Explore Northwood Lake-Old Dump 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
11 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330011 samples · 2020–2023
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
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
Impairment status from EPA ATTAINS 303(d) database