Lake Sunapee
Sullivan County, New Hampshire4,090 acresView mapDirections
NHDES publishes the water-quality measurements for Lake Sunapee. Here is what has been measured.
- Impaired · Mercury
- Public access
- Limited data
Lake Sunapee in Sullivan County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Water clarity: 26.7 ft visibility. Surface area: 4090 acres.
Lake Sunapee is a 4,090-acre lake in Sullivan County, New Hampshire. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-07-18. Methodology: how these readings are compared.
What Lake Sunapee is good for
From access and monitoring records, not editorial picks.
- Clear water26.7 ft of visibility
- Boat launch1 documented ramp
- Big water4,090 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Lake Sunapee is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Whether Lake Sunapee 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 Sunapee
These are the measurements NHDES publishes for Lake Sunapee, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 26.7 ft down. TSI 30.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 26.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading 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. | 30 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Lake Sunapee
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
4,090 acres
Public access
Yes
Listed by NHDES
No bathymetric survey has been published for Lake Sunapee, so its depth is not documented here.
Recreation & Access
- Burkehaven HarborPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Lake Sunapee
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Top-rated places to stay near Lake Sunapee
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Fishing Lake Sunapee
Reservoir Info (USACE NID)
Lake Sunapee is a man-made reservoir impounded by the Sunapee Lake Dam (completed 1872), built primarily for recreation on the Sugar River; concrete-type dam, 14 ft tall and 80 ft long.
- Surface area
- 4,090 ac
- Normal storage
- 19,800 ac-ft
- Max storage
- 40,900 ac-ft
- Drainage area
- 44.8 sq mi
- Hazard class
- Significant
- Owner
- NH DES WATER DIVISION
Source: USACE National Inventory of Dams, NID ID NH00108 · Operator website
EPA Impairment Status
Lake Sunapee 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.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK801060402-05-01 · Official waterbody report
Nearby Lakes in Sullivan County
Frequently asked questions about Lake Sunapee
Where is Lake Sunapee?
- Lake Sunapee 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 Lake Sunapee?
- Lake Sunapee in Sullivan County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Water clarity: 26.7 ft visibility. Surface area: 4090 acres.
Is Lake Sunapee safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Sunapee is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Are there boat ramps on Lake Sunapee?
- Lake Sunapee has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Burkehaven Harbor. Public access is listed as yes.
Can I fish at Lake Sunapee?
- Lake Sunapee has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by New Hampshire's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
6 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- North American Lake Management Society
NALMS6 samples · 2024
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
Named boat-access points from the USGS National Boat Ramps inventory