Willis Lake
Hamilton County, New YorkView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #4 of 4 in the county
- Limited data
Willis Lake in Hamilton County, New York has a water quality grade of A (Excellent). Phosphorus: 8 µg/L. Chlorophyll-a (algae): 0.5 µg/L.
- Type
- Oligotrophic
- Trend
- ↑ Improving
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Watch Willis Lake’s letter
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Willis Lake is a cold, clear oligotrophic lake in Hamilton County, New York. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in Hamilton County, Willis Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, NYSDEC, last sampled 2023-07-12. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
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. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Phosphorus 8 µg/L. Chlorophyll-a 0.5 µg/L. TSI 29. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 8 µg/L | Good |
| Chlorophyll-a (Algae) | 0.5 µg/L | Good |
| Trophic State Index (TSI) | 29 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Willis Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -0.5 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -0.65 µg/L/yr | 3 |
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Willis Lake under Clean Water Act (NPDES) discharge permits.
- Sacandaga CampgroundWells · 2.1 mi away · NPDES NY0034371
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.
County Ranking
Ranked #4 of 4 lakes in Hamilton County
Nearby Lakes in Hamilton County
Frequently asked questions about Willis Lake
Where is Willis Lake?
- Willis Lake is a lake in Hamilton County, New York. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Willis Lake?
- Willis Lake in Hamilton County, New York has a water quality grade of A (Excellent). Phosphorus: 8 µg/L. Chlorophyll-a (algae): 0.5 µg/L.
Is Willis Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Willis Lake across LakeQuality
Species activity outlook by water temperature and season
Top lakes and where to stay in the Adirondacks area
Where to stay at New York's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Other Grade A Lakes in New York
Oligotrophic Lakes in New York
Where this data comes from
6 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS New York Water Science Center
USGS-NY6 samples · 2020–2023
Analytical methods
- P, wu, WCA, persulfate CF color
- Chlorophyll a,fluorometric,uncor
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)