North Mountain Lake-Beach
North Mountain Lake-Beach in Grafton County, New Hampshire is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 9.2 µg/L. Surface area: 27 acres.
- Area
- 27 acres
Why North Mountain Lake-Beach has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For North Mountain Lake-Beach, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded phosphorus, but not water clarity and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
North Mountain Lake-Beach is a 27-acre lake in Grafton County, New Hampshire.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-05. 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 North Mountain Lake-Beach
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 9.2 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 9.2 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near North Mountain Lake-Beach
Compare lakeside cabins, hotels, and vacation rentals near North Mountain Lake-Beach in Grafton 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 North Mountain Lake-Beach
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 27 acres |
No bathymetric survey has been published for North Mountain Lake-Beach, so its depth is not documented here.
Fishing North Mountain Lake-Beach
Reservoir Info (USACE NID)
North Mountain Lake-Beach is a man-made reservoir impounded by the Upper Mountain Lake Dam (completed 1963), built primarily for recreation on the Waterman Brook; earth-type dam, 31 ft tall and 660 ft long.
- Surface area
- 27 ac
- Normal storage
- 325 ac-ft
- Max storage
- 499 ac-ft
- Drainage area
- 3.4 sq mi
- Hazard class
- Low
- Owner
- MOUNTAIN LAKES VILLAGE DISTRICT
Source: USACE National Inventory of Dams, NID ID NH00190 · Operator website · Matched by proximity (0.08 km)
EPA Impairment Status
North Mountain Lake-Beach 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 NHLAK801030505-04 · Official waterbody report · Matched by proximity (0.34 km)
Graded lakes near North Mountain Lake-Beach
North Mountain Lake-Beach has no grade, but these lakes within a short drive do.
Nearby Lakes in Grafton County
Frequently asked questions about North Mountain Lake-Beach
Where is North Mountain Lake-Beach?
- North Mountain Lake-Beach is a lake in Grafton County, New Hampshire. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for North Mountain Lake-Beach?
- North Mountain Lake-Beach in Grafton County, New Hampshire is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 9.2 µg/L. Surface area: 27 acres.
Is North Mountain Lake-Beach safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. North Mountain Lake-Beach is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Explore North Mountain Lake-Beach 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
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Other Lakes in New Hampshire
Oligotrophic Lakes in New Hampshire
Where this data comes from
2 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
111133002 samples · 2024–2025
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