Lk Ontario Lake is a productive, nutrient-rich eutrophic lake in Monroe County, New York. Water quality is graded D based on 2 sampling years through 2023. The lake supports 3 documented fish species including Brown Trout, Cisco, and Rainbow Trout. Public access is available. Compared to the 4 other monitored lakes in Monroe County, Lk Ontario Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, New York DNR, last sampled 2023-10-24. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
No clarity data. Phosphorus level: 126 µg/L. Chlorophyll-a: 17.1 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 126 µg/L | F |
| Chlorophyll-a (Algae) | 17.1 µg/L | C |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lk Ontario Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Lk Ontario Lake
Water Temperature
Lk Ontario Lake averages about 72°F at the surface in summer, usually warmest in Jul (about 77°F) and coldest in Apr (about 41°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 28 field readings (2018–2023) via the EPA Water Quality Portal. See the full Lk Ontario Lake water temperature breakdown →
Location
County Ranking
Ranked #4 of 5 lakes in Monroe County
Cleaner Lakes Within 30 Miles
Lk Ontario Lake holds Grade D. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Monroe County
Explore Lk Ontario Lake across LakeGrade
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Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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More records, surveys & data sources
EPA Impairment Status
Lk Ontario Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit NY0301-0016 · Official waterbody report · Matched by proximity (0.98 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
9 EPA-permitted facilities operate within about 5 miles of Lk Ontario Lake under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 2 facilities have a reported Clean Water Act violation in the past three years.
- Northwest Quad Pw Dist#1Hilton · 2 mi away · NPDES NY0028231MajorRecent violation
- R G & E Russell Generating StationRochester · 4.6 mi away · NPDES NY0000612Major
- Monroe Co Water AuthorityRochester · 4 mi away · NPDES NY0063673Recent violation
- Robert Bayley ResidenceHilton · 1.3 mi away · NPDES NY0227676
- Bucci PropertyGreece · 1.3 mi away · NPDES NY0162744
- Albrecht PropertyHilton · 2.1 mi away · NPDES NY0271730
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-10-24
Monitoring stations: 1