Lake Winnisquam Mohawk Isl-Deep Spot
Belknap County, New HampshireView mapDirections
NHDES publishes the water-quality measurements for Lake Winnisquam Mohawk Isl-Deep Spot. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
Lake Winnisquam Mohawk Isl-Deep Spot in Belknap County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 10.4 µg/L. Chlorophyll-a (algae): 1.2 µg/L.
Lake Winnisquam Mohawk Isl-Deep Spot is a cold, clear oligotrophic lake in Belknap County, New Hampshire. Compared to the 26 other monitored lakes in Belknap County, Lake Winnisquam Mohawk Isl-Deep Spot ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-27. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Lake Winnisquam Mohawk Isl-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5R) for mercury, nuisance exotic species, pH / acidity, turbidity. Check local advisories before you swim.
Whether Lake Winnisquam Mohawk Isl-Deep Spot is safe to swim in today is a call for the New Hampshire Department of Environmental Services and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Winnisquam Mohawk Isl-Deep Spot
These are the measurements NHDES publishes for Lake Winnisquam Mohawk Isl-Deep Spot, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 10.4 µg/L. Chlorophyll-a 1.2 µg/L. TSI 35.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 10.4µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 1.2µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 35 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
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Answers come straight from the public measurements and survey records on this page.
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Fishing Lake Winnisquam Mohawk Isl-Deep Spot
EPA Impairment Status
Lake Winnisquam Mohawk Isl-Deep Spot is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Designated uses not supporting: Aquatic life, Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700020201-05-01 · Official waterbody report
Nearby Lakes in Belknap County
Frequently asked questions about Lake Winnisquam Mohawk Isl-Deep Spot
Where is Lake Winnisquam Mohawk Isl-Deep Spot?
- Lake Winnisquam Mohawk Isl-Deep Spot is a lake in Belknap County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Lake Winnisquam Mohawk Isl-Deep Spot?
- Lake Winnisquam Mohawk Isl-Deep Spot in Belknap County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 10.4 µg/L. Chlorophyll-a (algae): 1.2 µg/L.
Is Lake Winnisquam Mohawk Isl-Deep Spot safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Winnisquam Mohawk Isl-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5R) for mercury, nuisance exotic species, pH / acidity, turbidity. Check local advisories before you swim.
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More lakes in New Hampshire
Other Lakes in New Hampshire
Oligotrophic Lakes in New Hampshire
Where this data comes from
77 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)
1111330077 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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database