Mill Pond
Sullivan County, New HampshireView mapDirections
NHDES publishes the water-quality measurements for Mill Pond. Here is what has been measured.
- Mesotrophic
- Impaired · Algal growth
Mill Pond in Sullivan County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 28.9 µg/L. Chlorophyll-a (algae): 4 µg/L.
Mill Pond is a mesotrophic lake in Sullivan County, New Hampshire. Compared to the 23 other monitored lakes in Sullivan County, Mill Pond ranks #22 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-07-27. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
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. Mill Pond is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, pH / acidity. Check local advisories before you swim.
Whether Mill Pond 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 Mill Pond
These are the measurements NHDES publishes for Mill Pond, 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 28.9 µg/L. Chlorophyll-a 4 µg/L. TSI 48.
| 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 | 28.9µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 4µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 48 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
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Stays via Stay22
Stays near Mill Pond
Compare lakeside cabins, hotels, and vacation rentals near Mill Pond 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Mill Pond are listed below.
Top-rated places to stay near Mill Pond
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Fishing Mill Pond
EPA Impairment Status
Mill Pond is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHIMP700030204-05-01 · Official waterbody report
Nearby Lakes in Sullivan County
Frequently asked questions about Mill Pond
Where is Mill Pond?
- Mill Pond is a lake in Sullivan County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Mill Pond?
- Mill Pond in Sullivan County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 28.9 µg/L. Chlorophyll-a (algae): 4 µg/L.
Is Mill Pond safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Mill Pond is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, pH / acidity. Check local advisories before you swim.
Explore Mill Pond across LakeQuality
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Where this data comes from
14 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330014 samples · 2021–2025
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