Crystal Lake-Deep Spot
Crystal Lake-Deep Spot in Hillsborough County, New Hampshire has a water quality grade of C (Fair). Phosphorus: 16.9 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
- Type
- Mesotrophic
Crystal Lake-Deep Spot is a mesotrophic lake in Hillsborough County, New Hampshire. Water quality is graded C based on 2 sampling years through 2025. Compared to the 35 other monitored lakes in Hillsborough County, Crystal Lake-Deep Spot ranks #19 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-07-30. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
No clarity data. Phosphorus level: 16.9 µg/L. Chlorophyll-a: 2.8 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 16.9 µg/L | Fair |
| Chlorophyll-a (Algae) | 2.8 µg/L | Good |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Crystal Lake-Deep Spot
Compare lakeside cabins, hotels, and vacation rentals near Crystal Lake-Deep Spot in Hillsborough 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 Crystal Lake-Deep Spot
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Fishing Crystal Lake-Deep Spot
EPA Impairment Status
Crystal Lake-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 NHLAK700060703-02-01 · Official waterbody report · Matched by proximity (0.01 km)
County Ranking
Ranked #19 of 36 lakes in Hillsborough County
Nearby Lakes in Hillsborough County
Frequently asked questions about Crystal Lake-Deep Spot
Where is Crystal Lake-Deep Spot?
- Crystal Lake-Deep Spot is a lake in Hillsborough County, New Hampshire. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Crystal Lake-Deep Spot?
- Crystal Lake-Deep Spot in Hillsborough County, New Hampshire has a water quality grade of C (Fair). Phosphorus: 16.9 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
Is Crystal Lake-Deep Spot safe to swim in?
- Generally safe for swimming, moderate water quality. Crystal Lake-Deep Spot has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 2.8 µg/L. Always check local health department advisories before swimming.
Explore Crystal Lake-Deep Spot across LakeGrade
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Other Grade C Lakes in New Hampshire
Mesotrophic Lakes in New Hampshire
Where this data comes from
31 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330031 samples · 2020–2025
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