Forest Lake
Washington County, VermontView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #6 of 9 in the county
- 35 ft max depth
- Public access
Forest Lake in Washington County, Vermont has a water quality grade of A (Excellent). Water clarity: 25.6 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.2 µg/L.
- Clarity
- 25.6 ft
- Max depth
- ~35 ft est.
- Type
- Oligotrophic
- Phosphorus
- 7 µg/L
- Chlorophyll-a
- 1.2 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
Stays via Stay22
Stays near Forest Lake
Compare lakeside cabins, hotels, and vacation rentals near Forest Lake in Washington County, Vermont — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Forest Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Forest Lake → · more Vermont lake trips
Watch Forest Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Forest Lake is a cold, clear oligotrophic lake in Washington County, Vermont with an estimated average depth of about 35 feet. Water quality is graded A based on 2 sampling years through 2025. 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 Washington County, Forest Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-26. Grade methodology: LakeQuality methodology.
What Forest Lake is good for
From access and monitoring records, not editorial picks.
- Clear water25.6 ft of visibility
Swimming Safety
Grade onlyLow algae
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. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Crystal clear, you can see 25.6 ft down. Phosphorus 7 µg/L. Chlorophyll-a 1.2 µg/L. TSI 32. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 25.6 ft | Not graded |
| Phosphorus | 7 µg/L | Good |
| Chlorophyll-a (Algae) | 1.2 µg/L | Good |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~35 ft est. |
| Average Depth | ~25 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 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.131 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.35 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.45 µg/L/yr | 6 |
County Ranking
Ranked #6 of 9 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Forest Lake
Where is Forest Lake?
- Forest Lake is a lake in Washington County, Vermont. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Forest Lake?
- Forest Lake in Washington County, Vermont has a water quality grade of A (Excellent). Water clarity: 25.6 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.2 µg/L.
Is Forest Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. 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 35 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
Species activity outlook by water temperature and season
Where to stay at Vermont's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
Vermont's cleanest and most-polluted lakes, ranked
More Vermont Lake Rankings
Other Grade A Lakes in Vermont
Oligotrophic Lakes in Vermont
Where this data comes from
83 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ83 samples · 2021–2025
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 (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
Lake size & watershed from HydroLAKES (HydroSHEDS)