Little Long Pond is a mesotrophic lake in Suffolk County, New York. Water quality is graded B based on 1 sampling years through 2020. The lake supports 3 documented fish species including Brook Trout, Rainbow Trout, and Splake. Compared to the 4 other monitored lakes in Suffolk County, Little Long Pond 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
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 10 ft. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Little Long Pond
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Little Long Pond
Location
County Ranking
Ranked #1 of 5 lakes in Suffolk County
Nearby Lakes in Suffolk County
Explore Little Long Pond across LakeGrade
Fish species and top-graded lakes across New York
Species activity outlook by water temperature and season
Where to stay at New York's top lakes, each with its grade
Moderate nutrients, good water quality
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Other Grade B Lakes in New York
Mesotrophic Lakes in New York
More records, surveys & data sources
EPA Impairment Status
Little Long Pond is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NY1701-0035 · Official waterbody report · Matched by proximity (2.69 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Little Long Pond under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Sag Harbor (V) WwtpSag Harbor · 1.8 mi away · NPDES NY0028908Recent violation
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: 2020-09-20
Monitoring stations: 1