Isle la Motte Lake
Grand Isle County, VermontView mapDirections
Vermont DEC publishes the water-quality measurements for Isle la Motte Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- Public access
Isle la Motte Lake in Grand Isle County, Vermont has water-quality measurements published by Vermont DEC, shown here as reported. Water clarity: 15.1 ft visibility. Phosphorus: 19.9 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
Isle la Motte Lake is a mesotrophic lake in Grand Isle County, Vermont. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 2 other monitored lakes in Grand Isle County, Isle la Motte Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-21. Methodology: how these readings are compared.
Isle la Motte Lake has 2 public boat landings, so a lakefront rental is not the only way to get a boat on the water. If you are planning to stay, you can search lake houses and cabins around Isle la Motte Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Isle la Motte Lake is good for
From access and monitoring records, not editorial picks.
- Clear water15.1 ft of visibility
- Boat launch2 documented ramps
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Isle la Motte Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Whether Isle la Motte Lake is safe to swim in today is a call for the Vermont Department of Environmental Conservation and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Isle la Motte Lake
These are the measurements Vermont DEC publishes for Isle la Motte Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 15.1 ft down. Phosphorus 19.9 µg/L. Chlorophyll-a 3.2 µg/L. TSI 42.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 15.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 19.9µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 3.2µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 42 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Isle la Motte Lake
Answers come straight from the public measurements and survey records on this page.
Recreation & Access
- Holcomb BayPublic
- Stoney PointPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Isle la Motte Lake
Compare lakeside cabins, hotels, and vacation rentals near Isle la Motte Lake in Grand Isle 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 Isle la Motte Lake
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Fishing Isle la Motte Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening5 years
Phosphorus
Improving-0.99 µg/L/yr5 years
Chlorophyll-a
Worsening+0.4 µg/L/yr5 years
EPA Impairment Status
Isle la Motte Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation, Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit VT05-04L02_01 · Official waterbody report
Nearby Lakes in Grand Isle County
Frequently asked questions about Isle la Motte Lake
Where is Isle la Motte Lake?
- Isle la Motte Lake is a lake in Grand Isle County, Vermont. Its water-quality measurements are published by Vermont DEC and shown on this page as reported.
What is the water quality of Isle la Motte Lake?
- Isle la Motte Lake in Grand Isle County, Vermont has water-quality measurements published by Vermont DEC, shown here as reported. Water clarity: 15.1 ft visibility. Phosphorus: 19.9 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
Is Isle la Motte Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Isle la Motte Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Are there boat ramps on Isle la Motte Lake?
- Isle la Motte Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Holcomb Bay, Stoney Point. Public access is listed as yes.
Can I fish at Isle la Motte Lake?
- Isle la Motte Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Vermont's fish and wildlife agency, so check its current regulations before you go.
Explore Isle la Motte Lake across LakeQuality
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Other Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
121 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
1VTDECWQ121 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 (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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