Forest Lake
Rensselaer County, New YorkView 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 · Mercury
- Limited data
Forest Lake in Rensselaer County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.4 ft visibility.
- Clarity
- 8.4 ft
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Watch Forest Lake’s letter
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Why Forest Lake has no grade
Forest Lake 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, Forest Lake is Not Rated — not an F. Its 8.4-foot median from 6 readings collected 2020 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 NYSDEC and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Forest Lake is a lake in Rensselaer County, New York.
Source: EPA Water Quality Portal sampling records, NYSDEC, last sampled 2020-09-06. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Forest Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Water quality measurements for Forest Lake
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 8.4 ft. TSI 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.4 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Forest Lake
EPA Impairment Status
Forest Lake 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 NY1301-0262 · Official waterbody report · Matched by proximity (2.78 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Forest Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Grafton QuarryGrafton · 3.8 mi away · NPDES NY0261025Recent violation
- Fane Cropseyville QuarryBrunswick · 4.3 mi away · NPDES NY0223794
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Rensselaer County
Frequently asked questions about Forest Lake
Where is Forest Lake?
- Forest Lake is a lake in Rensselaer County, New York. 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 Forest Lake?
- Forest Lake in Rensselaer County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.4 ft visibility.
Is Forest Lake safe to swim in?
- The letter is not a swimming clearance. Forest Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
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Where this data comes from
6 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS6 samples · 2020
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)