Forest Lake
Essex County, VermontView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- Impaired · Hydrologic alteration
- #8 of 9 in the county
- 18 ft max depth
- Public access
- Limited data
Forest Lake in Essex County, Vermont has a water quality grade of C (Fair). Water clarity: 4.1 ft visibility. Phosphorus: 16.8 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
- Clarity
- 4.1 ft
- Max depth
- ~18 ft est.
- Type
- Mesotrophic
- Phosphorus
- 16.8 µg/L
- Chlorophyll-a
- 5.5 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Forest Lake’s letter
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Forest Lake is a mesotrophic lake in Essex County, Vermont with an estimated average depth of about 18 feet. Water quality is graded C based on 1 sampling years through 2022. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 8 other monitored lakes in Essex County, Forest Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2022-08-30. 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 C is nutrients and algae, not a swimming clearance. Forest Lake is listed impaired under Clean Water Act §303(d) (IR 4C) for hydrologic alteration. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 4.1 ft. Phosphorus 16.8 µg/L. Chlorophyll-a 5.5 µg/L. TSI 50. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.1 ft | Not graded |
| Phosphorus | 16.8 µg/L | Fair |
| Chlorophyll-a (Algae) | 5.5 µg/L | Not graded |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~18 ft est. |
| Average Depth | ~15 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Vermont has not published bathymetry for Forest Lake.
Lake Size & Watershed
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.
Fishing Forest Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.045 m/yr | 4 |
| Phosphorus | ↑ Improving | -2.95 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.67 µg/L/yr | 4 |
EPA Impairment Status
Forest Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4C).
Causes of impairment
Source: EPA ATTAINS assessment unit VT17-03L02 · Official waterbody report · Matched by proximity (1.66 km)
County Ranking
Ranked #8 of 9 lakes in Essex County
Nearby Lakes With Higher Grades
Forest Lake holds Grade C. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Essex County
Frequently asked questions about Forest Lake
Where is Forest Lake?
- Forest Lake is a lake in Essex County, Vermont. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Forest Lake?
- Forest Lake in Essex County, Vermont has a water quality grade of C (Fair). Water clarity: 4.1 ft visibility. Phosphorus: 16.8 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
Is Forest Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Forest Lake is listed impaired under Clean Water Act §303(d) (IR 4C) for hydrologic alteration. Check local advisories before you swim.
How deep is Forest Lake?
- No published bathymetric survey covers Forest Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 18 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Forest Lake across LakeQuality
More Vermont Lake Rankings
Other Grade C Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
10 measurements from 3 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ10 samples · 2022
Analytical methods
- EPA approved Alternate Test Procedure for 4500 P H. Has a 28 day hold without acid preservation.
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (3)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)