South Bay Lake
Orleans County, VermontView mapDirections
Nutrients and algae sit mid-range for this region.
- Mesotrophic
- #13 of 17 in the county
- 23 ft max depth
- Public access
South Bay Lake in Orleans County, Vermont has a water quality grade of C (Fair). Water clarity: 4.4 ft visibility. Phosphorus: 22.7 µg/L. Chlorophyll-a (algae): 6 µg/L.
- Clarity
- 4.4 ft
- Max depth
- ~23 ft est.
- Type
- Mesotrophic
- Phosphorus
- 22.7 µg/L
- Chlorophyll-a
- 6 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch South Bay Lake’s letter
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South Bay Lake is a mesotrophic lake in Orleans County, Vermont with an estimated average depth of about 23 feet. Water quality is graded C 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 with 1 public boat landing. Compared to the 16 other monitored lakes in Orleans County, South Bay Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-10-06. Grade methodology: LakeQuality methodology.
What South Bay Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Grade onlyModerate
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. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 4.4 ft. Phosphorus 22.7 µg/L. Chlorophyll-a 6 µg/L. TSI 51. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.4 ft | Not graded |
| Phosphorus | 22.7 µg/L | Fair |
| Chlorophyll-a (Algae) | 6 µg/L | Fair |
| Trophic State Index (TSI) | 51 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~23 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 South Bay 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.
Recreation & Access
- South BayPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing South Bay Lake
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.17 m/yr | 4 |
| Phosphorus | ↑ Improving | -1.12 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -1.68 µg/L/yr | 6 |
County Ranking
Ranked #13 of 17 lakes in Orleans County
Nearby Lakes With Higher Grades
South Bay Lake holds Grade C. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Orleans County
Frequently asked questions about South Bay Lake
Where is South Bay Lake?
- South Bay Lake is a lake in Orleans County, Vermont. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for South Bay Lake?
- South Bay Lake in Orleans County, Vermont has a water quality grade of C (Fair). Water clarity: 4.4 ft visibility. Phosphorus: 22.7 µg/L. Chlorophyll-a (algae): 6 µg/L.
Is South Bay Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is South Bay Lake?
- No published bathymetric survey covers South Bay Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 23 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on South Bay Lake?
- South Bay Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include South Bay. Public access is listed as yes.
Explore South Bay Lake across LakeQuality
More Vermont Lake Rankings
Other Grade C Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
119 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ119 samples · 2020–2025
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)
Named boat-access points from the USGS National Boat Ramps inventory