Pratt Pond-Deep Spot
Hillsborough County, New Hampshire35 acresView mapDirections
NHDES publishes the water-quality measurements for Pratt Pond-Deep Spot. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- Limited data
Pratt Pond-Deep Spot in Hillsborough County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 10.7 µg/L. Chlorophyll-a (algae): 8.2 µg/L. Surface area: 35 acres.
Pratt Pond-Deep Spot is a 35-acre mesotrophic lake in Hillsborough County, New Hampshire. Compared to the 35 other monitored lakes in Hillsborough County, Pratt Pond-Deep Spot ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-04. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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. Pratt Pond-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, pH / acidity. Check local advisories before you swim.
Whether Pratt Pond-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 Pratt Pond-Deep Spot
These are the measurements NHDES publishes for Pratt Pond-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 10.7 µg/L. Chlorophyll-a 8.2 µg/L. TSI 45.
| 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 | 10.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 8.2µg/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. | 45 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Pratt Pond-Deep Spot
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
35 acres
No bathymetric survey has been published for Pratt Pond-Deep Spot, so its depth is not documented here.
Stays via Stay22
Stays near Pratt Pond-Deep Spot
Compare lakeside cabins, hotels, and vacation rentals near Pratt Pond-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 Pratt Pond-Deep Spot
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Follow Pratt Pond-Deep Spot’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Pratt Pond-Deep Spot
Reservoir Info (USACE NID)
Pratt Pond-Deep Spot is a man-made reservoir impounded by the Pratt Pond Dam (completed 1890), built primarily for recreation on the Pratt Brook; earth-type dam, 7 ft tall and 150 ft long.
- Surface area
- 35 ac
- Normal storage
- 58 ac-ft
- Max storage
- 110 ac-ft
- Drainage area
- 0.74 sq mi
- Hazard class
- Low
- Owner
- PRATT POND ASSOCIATION
Source: USACE National Inventory of Dams, NID ID NH00557 · Operator website · Matched by proximity (0.6 km)
EPA Impairment Status
Pratt Pond-Deep Spot is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
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 NHLAK700060901-03 · Official waterbody report
Nearby Lakes in Hillsborough County
Frequently asked questions about Pratt Pond-Deep Spot
Where is Pratt Pond-Deep Spot?
- Pratt Pond-Deep Spot is a lake in Hillsborough County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Pratt Pond-Deep Spot?
- Pratt Pond-Deep Spot in Hillsborough County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 10.7 µg/L. Chlorophyll-a (algae): 8.2 µg/L. Surface area: 35 acres.
Is Pratt Pond-Deep Spot safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Pratt Pond-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, pH / acidity. Check local advisories before you swim.
Explore Pratt Pond-Deep Spot across LakeQuality
More lakes in New Hampshire
Other Lakes in New Hampshire
Mesotrophic Lakes in New Hampshire
Where this data comes from
8 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)
111133008 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