Safest Lakes to Swim in Vermont
Lake St. Catherine (Rutland County) ranks #1 for swimming in Vermont — grade A water with low algae and public access. Below: the top 25 lakes in Vermontthat pass our swim-safety filter (grade A/B, chlorophyll-a below 10 µg/L).
Best-for-swimming on LakeGrade weights water clarity heavily: a swimmer cares whether they can see their feet, whether the water looks inviting on a 90-degree July day, and whether there is a real harmful-algal-bloom risk. The top {{stateName}} swimming lake on current data is Lake St. Catherine (A).
The swimming-best list filters more aggressively on chlorophyll-a than the cleanest list — even very clear lakes can have harmful-algal-bloom risk under specific conditions, so the swimming ranking is more conservative on that front.
| Rank | Lake | County | Grade | Swim Safety | Clarity | Algae | Phosphorus | Area |
|---|---|---|---|---|---|---|---|---|
| 1 | Lake St. Catherine | Rutland | A | Low algae | 15.4 ft | 2.7 µg/L | 13.2 µg/L | - |
| 2 | Valley Lake | Washington | A | Low algae | 24.4 ft | 2.9 µg/L | 16.7 µg/L | - |
| 3 | Beebe Pond | Rutland | A | Low algae | 24.6 ft | 1.3 µg/L | 9.9 µg/L | - |
| 4 | Peacham Pond | Caledonia | A | Low algae | 15.6 ft | 2 µg/L | 10.5 µg/L | - |
| 5 | Berlin Pond | Washington | A | Low algae | 21.7 ft | 1 µg/L | 7.1 µg/L | - |
| 6 | Caspian Lake | Orleans | A | Low algae | 29.5 ft | 1.3 µg/L | 7.8 µg/L | - |
| 7 | Harveys Lake | Caledonia | A | Low algae | 21 ft | 1.3 µg/L | 8.4 µg/L | - |
| 8 | Maidstone Lake | Essex | A | Low algae | 28.5 ft | 1.4 µg/L | 7.2 µg/L | - |
| 9 | Nichols Pond | Washington | A | Low algae | 23.3 ft | — | 8.6 µg/L | - |
| 10 | Rescue Lake | Windsor | A | Low algae | 15.1 ft | 2.2 µg/L | 10.7 µg/L | - |
| 11 | Seymour Lake | Orleans | A | Low algae | 24.6 ft | 1.3 µg/L | 7.8 µg/L | - |
| 12 | Sabin Pond | Washington | A | Low algae | 15.7 ft | 2.1 µg/L | 9.6 µg/L | - |
| 13 | Long Pond | Orleans | A | Low algae | — | 3.2 µg/L | 15.6 µg/L | - |
| 14 | Curtis Pond | Washington | A | Low algae | 15.3 ft | 3.3 µg/L | 13.3 µg/L | - |
| 15 | Lake Fairlee | Orange | A | Low algae | 21.7 ft | 2.8 µg/L | 14.5 µg/L | - |
| 16 | Echo Lake | Orleans | A | Low algae | 23 ft | 1.6 µg/L | 8 µg/L | - |
| 17 | Echo Lake | Rutland | A | Low algae | 24.3 ft | 1.3 µg/L | 10.1 µg/L | - |
| 18 | Lake Morey | Orange | A | Low algae | 19.7 ft | 2.8 µg/L | 14.3 µg/L | - |
| 19 | Little Averill Pond | Essex | A | Low algae | 19.4 ft | 1.6 µg/L | 6.6 µg/L | - |
| 20 | Lake Willoughby | Orleans | A | Low algae | 28.2 ft | 1.6 µg/L | 7.8 µg/L | - |
| 21 | South Pond | Lamoille | A | Low algae | 15.4 ft | 2.4 µg/L | 8.2 µg/L | - |
| 22 | Lake Mirror | Washington | A | Low algae | 21.3 ft | 2.6 µg/L | 10.6 µg/L | - |
| 23 | Lake Dunmore | Addison | A | Low algae | 16.4 ft | 2.8 µg/L | 10.9 µg/L | - |
| 24 | Crystal Lake | Orleans | A | Low algae | 19.4 ft | 0.9 µg/L | 5.4 µg/L | - |
| 25 | Sunset Lake | Windham | A | Low algae | 17.9 ft | 1.8 µg/L | 8.9 µg/L | - |
Frequently Asked Questions
What is the best lake to swim in Vermont?
Lake St. Catherine in Rutland County ranks #1 for swimming-safety in our 2026 Vermont dataset, combining grade-A water clarity with low algae and public access. The full top 25 above ranks the swim-safest lakes statewide.
How do you know if a lake is safe to swim in Vermont?
Three signals: (1) water clarity — Secchi depth above 6 feet is a strong sign of low suspended sediment and pathogens; (2) chlorophyll-a below 10 µg/L means low risk of harmful algae bloom; (3) a current grade of A or B from year-round sampling. Vermont DNR and county health departments post seasonal advisories — always check before you swim, especially in late summer when blue-green algae bloom risk peaks.
Are lakes in Vermont safe to swim in?
Most monitored Vermont lakes are safe to swim in under normal conditions, but water quality varies widely. The lakes ranked above are filtered to grade A and B with chlorophyll-a below 10 µg/L — meaning they consistently test cleaner and have lower algae bloom risk than the state average. Always check posted advisories before swimming and avoid water after heavy rain (bacterial contamination spikes from runoff).
What lakes have algae blooms in Vermont?
Algae blooms (especially blue-green / cyanobacteria) are most common in shallow, warm, nutrient-rich (eutrophic) lakes during late summer. Lakes with high phosphorus and chlorophyll-a measurements are at higher risk. The lakes on this page are filtered to exclude high-algae lakes. For the opposite list, see our most-polluted-lakes trend page.
When is it safe to swim in lakes in Vermont?
Vermont lakes are typically safest to swim in late spring through early summer (May–July), when water is cool and algae bloom risk is lowest. Risk rises in late summer and early fall (August–September) when warm water and accumulated nutrients drive cyanobacteria blooms. Always avoid swimming after heavy rainfall (bacterial spikes from runoff) and check current state DNR advisories the day you go.
What's the cleanest lake in Vermont?
The single cleanest lake by combined water-quality score is featured on the Vermont cleanest-lakes page. The lakes here are filtered specifically for swimming safety — same A/B grade requirement, plus low chlorophyll-a (active algae filter). For the broader cleanliness ranking, see /best/cleanest/vt.
Our swimming-safety filter
We don't just rank by overall grade. Lakes here have to pass three filters:
- Grade A or B overall water quality (top 40% statewide)
- Chlorophyll-a below 10 µg/L — actively low algae density, low risk of harmful blue-green blooms
- Multi-year sampling data — excludes lakes with limited sampling history (data confidence)
The Swim Safety column adds a direct bacteria signal on top of the grade: where the EPA Water Quality Portal has enough E. coli or fecal-coliform samples, we show a historical swim-safety grade (how often the lake has exceeded the safe-swimming threshold). It is a record of past testing, never a live "safe today" reading — bacteria spike fast after rain.
The ranking within the filter is by combined water-quality score (Secchi clarity + phosphorus + chlorophyll-a). Always check current Vermont DNR advisories before swimming.
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Source: EPA National Aquatic Resource Surveys, 2026.