Sepasco Lake
Dutchess County, New YorkView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Nutrients (phosphorus, nitrogen)
- Limited data
Sepasco Lake in Dutchess County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.7 ft visibility.
- Clarity
- 8.7 ft
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Why Sepasco Lake has no grade
Sepasco Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Sepasco Lake is Not Rated — not an F. Its 8.7-foot median from 7 readings collected 2020 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by NYSDEC and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Sepasco Lake is a lake in Dutchess County, New York.
Source: EPA Water Quality Portal sampling records, NYSDEC, last sampled 2020-09-20. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Sepasco Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water quality measurements for Sepasco Lake
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 8.7 ft. TSI 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.7 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Sepasco Lake
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.
Nearby Lakes in Dutchess County
Frequently asked questions about Sepasco Lake
Where is Sepasco Lake?
- Sepasco Lake is a lake in Dutchess County, New York. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Sepasco Lake?
- Sepasco Lake in Dutchess County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.7 ft visibility.
Is Sepasco Lake safe to swim in?
- The letter is not a swimming clearance. Sepasco Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
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Where this data comes from
7 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS7 samples · 2020
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)