Ponkapoag Pond
Norfolk County, Massachusetts285 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Algal growth
- #2 of 2 in the county
- 52 ft max depth
- Limited data
Ponkapoag Pond in Norfolk County, Massachusetts has a water quality grade of A (Excellent). Chlorophyll-a (algae): 2.9 µg/L. Surface area: 285 acres.
- Max depth
- ~52 ft est.
- Area
- 285 acres
- Type
- Mesotrophic
- Chlorophyll-a
- 2.9 µg/L
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Watch Ponkapoag Pond’s letter
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Ponkapoag Pond is a 285-acre mesotrophic lake in Norfolk County, Massachusetts with an estimated average depth of about 52 feet. Water quality is graded A based on 1 sampling years through 2017. Compared to the 1 other monitored lakes in Norfolk County, Ponkapoag Pond ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2017-08-29. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
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.
The A is nutrients and algae, not a swimming clearance. Ponkapoag Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, mercury, nuisance exotic species. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Chlorophyll-a 2.9 µg/L. TSI 41. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 2.9 µg/L | Good |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~52 ft est. |
| Average Depth | ~16 ft est. |
| Surface Area | 285 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for Ponkapoag Pond.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Ponkapoag Pond
Reservoir Info (USACE NID)
Ponkapoag Pond is a man-made reservoir impounded by the Ponkapoag Pond Dam (completed 1930), built primarily for recreation on the Ponkapoag Brook; earth-type dam, 7 ft tall and 1,300 ft long.
- Surface area
- 285 ac
- Normal storage
- 1,126 ac-ft
- Max storage
- 1,653 ac-ft
- Drainage area
- 1.2 sq mi
- Hazard class
- Significant
- Owner
- MA Department of Conservation and Recreation
Source: USACE National Inventory of Dams, NID ID MA03107 · Operator website
EPA Impairment Status
Ponkapoag Pond is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MA73043 · Official waterbody report
County Ranking
Ranked #2 of 2 lakes in Norfolk County
Nearby Lakes in Norfolk County
Frequently asked questions about Ponkapoag Pond
Where is Ponkapoag Pond?
- Ponkapoag Pond is a lake in Norfolk County, Massachusetts. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Ponkapoag Pond?
- Ponkapoag Pond in Norfolk County, Massachusetts has a water quality grade of A (Excellent). Chlorophyll-a (algae): 2.9 µg/L. Surface area: 285 acres.
Is Ponkapoag Pond safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Ponkapoag Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, mercury, nuisance exotic species. Check local advisories before you swim.
How deep is Ponkapoag Pond?
- No published bathymetric survey covers Ponkapoag Pond, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 52 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 285 acres.
Explore Ponkapoag Pond across LakeQuality
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Where this data comes from
3 measurements from 1 monitoring station, 2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP3 samples · 2017
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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
Lake size & watershed from HydroLAKES (HydroSHEDS)