Isle la Motte Lake is a mesotrophic lake in Clinton County, New York. Water quality is graded A based on 3 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 2 other monitored lakes in Clinton County, Isle la Motte Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, New York DNR, last sampled 2024-10-22. Grade methodology: LakeGrade methodology.
Watch Isle la Motte Lake water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 12.5 ft. Phosphorus level: 12.3 µg/L. Chlorophyll-a: 4.6 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.5 ft | B |
| Phosphorus | 12.3 µg/L | A |
| Chlorophyll-a (Algae) | 4.6 µg/L | A |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Isle la Motte Lake
Compare lakeside cabins, hotels, and vacation rentals near Isle la Motte Lake in Clinton County, New York — 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: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.25 m/yr | 4 |
| Phosphorus | ↓ Declining | +0.99 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.26 µg/L/yr | 3 |
Water Temperature
Isle la Motte Lake averages about 68°F at the surface in summer, usually warmest in Aug (about 74°F) and coldest in Apr (about 44°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 1,772 field readings (2010–2023) via the EPA Water Quality Portal.
Location
County Ranking
Ranked #2 of 3 lakes in Clinton County
Nearby Lakes in Clinton County
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Moderate nutrients, good water quality
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More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Isle la Motte Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Rouses Point (V) WwtpRouses Point · 3.6 mi away · NPDES NY0021831MajorRecent violation
- Kings Bay Resort - WwtsChamplain · 1.7 mi away · NPDES NY0230464Recent violation
- Lake Champlain Rentals Campground And RestaurantChamplain · 1.8 mi away · NPDES NY0230570
- Wyeth PharmaceuticalsRouses Point · 3.1 mi away · NPDES NY0033421
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-10-22
Monitoring stations: 1