Spy Pond
Middlesex County, MassachusettsView mapDirections
MassDEP publishes the water-quality measurements for Spy Pond. Here is what has been measured.
- Impaired · Algal growth
- Limited data
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Answers come straight from the public measurements and survey records on this page.
Spy Pond in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Water clarity: 5 ft visibility.
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Spy Pond is a lake in Middlesex County, Massachusetts. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2024-07-26. Grade methodology: LakeQuality methodology.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Spy Pond is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, noxious aquatic plants, nuisance exotic species, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pesticides. Check local advisories before you swim.
Whether Spy Pond 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 Spy Pond
These are the measurements MassDEP publishes for Spy Pond, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5 ft. TSI 54.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Measured, not scored |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Spy Pond
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.289 m/yr | 5 |
EPA Impairment Status
Spy 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 MA71040 · Official waterbody report
Nearby Lakes in Middlesex County
Frequently asked questions about Spy Pond
Where is Spy Pond?
- Spy Pond is a lake in Middlesex County, Massachusetts. Its water-quality measurements are published by MassDEP and shown on this page as reported.
What is the water quality of Spy Pond?
- Spy Pond in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Water clarity: 5 ft visibility.
Is Spy Pond safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Spy Pond is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, noxious aquatic plants, nuisance exotic species, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pesticides. Check local advisories before you swim.
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Where this data comes from
9 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS9 samples · 2020–2024
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