Marshall Pond-Deep Spot
Marshall Pond-Deep Spot in Sullivan County, New Hampshire has a water quality grade of B (Good). Phosphorus: 11.4 µg/L.
- Type
- Oligotrophic
Marshall Pond-Deep Spot is a cold, clear oligotrophic lake in Sullivan County, New Hampshire. Water quality is graded B based on 1 sampling years through 2024. Compared to the 23 other monitored lakes in Sullivan County, Marshall Pond-Deep Spot ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-06-13. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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: 11.4 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 11.4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Marshall Pond-Deep Spot
Compare lakeside cabins, hotels, and vacation rentals near Marshall Pond-Deep Spot 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 Marshall Pond-Deep Spot
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Fishing Marshall Pond-Deep Spot
EPA Impairment Status
Marshall Pond-Deep Spot 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 NHLAK801060701-01 · Official waterbody report · Matched by proximity (0.1 km)
County Ranking
Ranked #17 of 24 lakes in Sullivan County
Nearby Lakes in Sullivan County
Frequently asked questions about Marshall Pond-Deep Spot
Where is Marshall Pond-Deep Spot?
- Marshall Pond-Deep Spot 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 Marshall Pond-Deep Spot?
- Marshall Pond-Deep Spot in Sullivan County, New Hampshire has a water quality grade of B (Good). Phosphorus: 11.4 µg/L.
Is Marshall Pond-Deep Spot safe to swim in?
- Good for swimming, clear water with low algae levels. Marshall Pond-Deep Spot has a water quality grade of B (Good). Always check local health department advisories before swimming.
Explore Marshall Pond-Deep Spot 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
Oligotrophic Lakes in New Hampshire
Where this data comes from
8 measurements from 1 monitoring station, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
111133008 samples · 2022–2024
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
- CHLOROPHYLL A-B-C DETERMINATION (MODIFIED)
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