Willys Lake
Herkimer County, New YorkView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · pH / acidity
- #4 of 6 in the county
- 26 ft max depth
- Limited data
Willys Lake in Herkimer County, New York has a water quality grade of A (Excellent). Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1 µg/L.
- Typical in September
- 68°F
- Max depth
- ~26 ft est.
- Type
- Oligotrophic
- Phosphorus
- 4 µg/L
- Chlorophyll-a
- 1 µg/L
- Trend
- ↓ Declining
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Watch Willys Lake’s letter
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Willys Lake is a cold, clear oligotrophic lake in Herkimer County, New York with an estimated average depth of about 26 feet. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 5 other monitored lakes in Herkimer County, Willys Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, NYSDEC, last sampled 2023-09-19. 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. Willys Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pH / acidity. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Phosphorus 4 µg/L. Chlorophyll-a 1 µg/L. TSI 27. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 4 µg/L | Good |
| Chlorophyll-a (Algae) | 1 µg/L | Good |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Water Temperature
Willys Lake typically sits around 68°F at the surface in September. Summer average is about 74°F. 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 →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~26 ft est. |
| Average Depth | ~19 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. New York has not published bathymetry for Willys Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
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 |
| Chlorophyll-a | ↓ Declining | +0.3 µg/L/yr | 3 |
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)
County Ranking
Ranked #4 of 6 lakes in Herkimer County
Nearby Lakes in Herkimer County
Frequently asked questions about Willys Lake
Where is Willys Lake?
- Willys Lake is a lake in Herkimer 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 Willys Lake?
- Willys Lake in Herkimer County, New York has a water quality grade of A (Excellent). Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1 µg/L.
Is Willys Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Willys Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pH / acidity. Check local advisories before you swim.
What is the water temperature of Willys Lake?
- Willys Lake typically sits around 68°F at the surface in September, from 26 EPA Water Quality Portal field readings (2017–2022). That is a typical value for the month, not a live reading.
How deep is Willys Lake?
- No published bathymetric survey covers Willys Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 26 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Willys Lake across LakeQuality
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Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
23 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-NY23 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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)