Malletts Bay Lake
Chittenden County, VermontView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Mercury
- #1 of 8 in the county
- Public access
Malletts Bay Lake in Chittenden County, Vermont has a water quality grade of A (Excellent). Water clarity: 13.8 ft visibility. Phosphorus: 10.2 µg/L. Chlorophyll-a (algae): 4 µg/L.
- Clarity
- 13.8 ft
- Type
- Mesotrophic
- Phosphorus
- 10.2 µg/L
- Chlorophyll-a
- 4 µg/L
- Public access
- Yes
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Malletts Bay Lake is a mesotrophic lake in Chittenden County, Vermont. Water quality is graded A based on 2 sampling years through 2025. Limited fish-species data available. Public access is available with 4 public boat landings. Compared to the 7 other monitored lakes in Chittenden County, Malletts Bay Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-26. Grade methodology: LakeQuality methodology.
What Malletts Bay Lake is good for
From access and monitoring records, not editorial picks.
- Clear water13.8 ft of visibility
- Boat launch4 documented ramps
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. Malletts Bay Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nuisance exotic species, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Good clarity, visible to about 13.8 ft. Phosphorus 10.2 µg/L. Chlorophyll-a 4 µg/L. TSI 40. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.8 ft | Not graded |
| Phosphorus | 10.2 µg/L | Good |
| Chlorophyll-a (Algae) | 4 µg/L | Good |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Recreation & Access
- Malletts BayPublic
- Colchester PointPublic
- Lamoille RiverPublic
- Bay Harbor MarinaSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Malletts Bay Lake
EPA Impairment Status
Malletts Bay Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit VT05-09L01_02 · Official waterbody report · Matched by proximity (1.81 km)
County Ranking
Ranked #1 of 8 lakes in Chittenden County
Nearby Lakes in Chittenden County
Frequently asked questions about Malletts Bay Lake
Where is Malletts Bay Lake?
- Malletts Bay Lake is a lake in Chittenden County, Vermont. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Malletts Bay Lake?
- Malletts Bay Lake in Chittenden County, Vermont has a water quality grade of A (Excellent). Water clarity: 13.8 ft visibility. Phosphorus: 10.2 µg/L. Chlorophyll-a (algae): 4 µg/L.
Is Malletts Bay Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Malletts Bay Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nuisance exotic species, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Are there boat ramps on Malletts Bay Lake?
- Malletts Bay Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Malletts Bay, Colchester Point, Lamoille River, Bay Harbor Marina. Public access is listed as yes.
Explore Malletts Bay Lake across LakeQuality
More Vermont Lake Rankings
Other Grade A Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
395 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ395 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
Monitoring station identifiers (2)
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
Named boat-access points from the USGS National Boat Ramps inventory