Marys Pond
Plymouth County, MassachusettsView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Mercury
- #3 of 12 in the county
- Limited data
Marys Pond in Plymouth County, Massachusetts has a water quality grade of A (Excellent). Chlorophyll-a (algae): 2.6 µg/L.
- Type
- Mesotrophic
- Chlorophyll-a
- 2.6 µg/L
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Watch Marys Pond’s letter
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Marys Pond is a mesotrophic lake in Plymouth County, Massachusetts. Water quality is graded A based on 1 sampling years through 2018. Compared to the 11 other monitored lakes in Plymouth County, Marys Pond ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2018-09-06. 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. Marys Pond is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Chlorophyll-a 2.6 µg/L. TSI 40. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 2.6 µg/L | Good |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Marys Pond
EPA Impairment Status
Marys Pond is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MA95100 · Official waterbody report
County Ranking
Ranked #3 of 12 lakes in Plymouth County
Nearby Lakes in Plymouth County
Frequently asked questions about Marys Pond
Where is Marys Pond?
- Marys Pond is a lake in Plymouth County, Massachusetts. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Marys Pond?
- Marys Pond in Plymouth County, Massachusetts has a water quality grade of A (Excellent). Chlorophyll-a (algae): 2.6 µg/L.
Is Marys Pond safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Marys Pond is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Explore Marys Pond across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Massachusetts's top lakes, each with its grade
Moderate nutrients, good water quality
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Where this data comes from
3 measurements from 1 monitoring station, 2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP3 samples · 2018
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