Spy Pond
Middlesex County, MassachusettsView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Algal growth
- Limited data
Spy Pond in Middlesex County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility.
- Clarity
- 5 ft
- Trend
- ↓ Declining
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Watch Spy Pond’s letter
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Why Spy Pond has no grade
Spy Pond has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Spy Pond is Not Rated — not an F. Its 5-foot median from 9 readings collected 2020–2024 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by MassDEP and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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 Safety
Not ratedLimited data
The letter is 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.
Water quality measurements for Spy Pond
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 5 ft. TSI 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| 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
Graded lakes near Spy Pond
Spy Pond has no grade, but these lakes within a short drive do.
Nearby Lakes in Middlesex County
Frequently asked questions about Spy Pond
Where is Spy Pond?
- Spy Pond is a lake in Middlesex County, Massachusetts. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Spy Pond?
- Spy Pond in Middlesex County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility.
Is Spy Pond safe to swim in?
- The letter is 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)
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