Willys Lake is a cold, clear oligotrophic lake in Herkimer County, New York. Water quality is graded A based on 1 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 6 other monitored lakes in Herkimer County, Willys Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, New York DNR, last sampled 2023-09-19. Grade methodology: LakeGrade methodology.
Watch Willys Lake water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
No clarity data. Phosphorus level: 4 µg/L. Trophic State Index: 24.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 4 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 24 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Willys Lake
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Fishing Willys Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +0.15 µg/L/yr | 4 |
Water Temperature
Willys Lake averages about 74°F at the surface in summer, usually warmest in Jul (about 74°F) and coldest in Feb (about 33°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 26 field readings (2017–2022) via the EPA Water Quality Portal. See the full Willys Lake water temperature breakdown →
Location
County Ranking
Ranked #6 of 7 lakes in Herkimer County
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Low nutrients, clear water, excellent for swimming
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More records, surveys & data sources
EPA Impairment Status
Willys Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NY0905-0026 · Official waterbody report · Matched by proximity (0.27 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-09-19
Monitoring stations: 1