Sepasco Lake is a mesotrophic lake in Dutchess County, New York. Water quality is graded C based on 1 sampling years through 2020. Compared to the 1 other monitored lakes in Dutchess County, Sepasco Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, New York DNR, last sampled 2020-09-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 8.7 ft. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.7 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Sepasco Lake
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Fishing Sepasco Lake
Location
County Ranking
Ranked #1 of 2 lakes in Dutchess County
Nearby Lakes in Dutchess County
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Moderate nutrients, good water quality
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EPA Impairment Status
Sepasco 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 NY1301-0214 · Official waterbody report
Regulated Pollution Sources Nearby
9 EPA-permitted facilities operate within about 5 miles of Sepasco Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Village Of Redhook WwtpRed Hook · 3.3 mi away · NPDES NY0271420Recent violation
- Rhinebeck (V) WwtfRhinebeck · 4.8 mi away · NPDES NY0110281Recent violation
- Bard CollegeAnnandale On Hudson · 2.6 mi away · NPDES NY0031925
- Rhinebeck Mhp WwtpRhinebeck, Town Of · 2.9 mi away · NPDES NY0102172
- Eddie A Parker Youth CenterRed Hook · 2.9 mi away · NPDES NY0141925
- Rikert Commercial DevelopmentRhinebeck · 3.1 mi away · NPDES NY0148903
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)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2020-09-20
Monitoring stations: 1