Lake Pearl
Norfolk County, Massachusetts288 acresView mapDirections
MassDEP publishes the water-quality measurements for Lake Pearl. Here is what has been measured.
- Oligotrophic
- Impaired · Nuisance exotic species
- 42 ft max depth
- Limited data
Lake Pearl in Norfolk County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 1.8 µg/L. Surface area: 288 acres.
Lake Pearl is a 288-acre cold, clear oligotrophic lake in Norfolk County, Massachusetts with an estimated average depth of about 42 feet. Compared to the 1 other monitored lakes in Norfolk County, Lake Pearl ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2017-08-29. 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. Lake Pearl is listed impaired under Clean Water Act §303(d) (IR 4A) for nuisance exotic species, oxygen depletion (low DO). Check local advisories before you swim.
Whether Lake Pearl is safe to swim in today is a call for the Massachusetts Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Pearl
These are the measurements MassDEP publishes for Lake Pearl, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Chlorophyll-a 1.8 µg/L. TSI 36.
| 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 | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 1.8µg/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. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Lake Pearl
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~42 ft est.
Surface area
288 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 Lake Pearl.
Lake Size & Watershed
Watershed (drainage) area
4 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.4 mi
HydroLAKES / HydroSHEDS
Elevation
203 ft
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.
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Fishing Lake Pearl
Reservoir Info (USACE NID)
Lake Pearl is a man-made reservoir impounded by the Red Dam (completed 1920), built primarily for recreation on the Eagle Brook; earth-type dam, 10 ft tall and 270 ft long.
- Surface area
- 288 ac
- Normal storage
- 1,400 ac-ft
- Max storage
- 2,260 ac-ft
- Drainage area
- 7.46 sq mi
- Hazard class
- Significant
- Owner
- Town of Wrentham
Source: USACE National Inventory of Dams, NID ID MA00170 · Operator website · Matched by proximity (0.41 km)
EPA Impairment Status
Lake Pearl is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Aquatic life.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MA72092 · Official waterbody report
Nearby Lakes in Norfolk County
Frequently asked questions about Lake Pearl
Where is Lake Pearl?
- Lake Pearl is a lake in Norfolk County, Massachusetts. Its water-quality measurements are published by MassDEP and shown on this page as reported.
What is the water quality of Lake Pearl?
- Lake Pearl in Norfolk County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 1.8 µg/L. Surface area: 288 acres.
Is Lake Pearl safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Pearl is listed impaired under Clean Water Act §303(d) (IR 4A) for nuisance exotic species, oxygen depletion (low DO). Check local advisories before you swim.
How deep is Lake Pearl?
- No published bathymetric survey covers Lake Pearl, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 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 288 acres.
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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)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)