South Reservoir is a cold, clear oligotrophic lake in Middlesex County, Massachusetts. Water quality is graded A based on 1 sampling years through 2017. Compared to the 14 other monitored lakes in Middlesex County, South Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Massachusetts DNR, last sampled 2017-09-14. Grade methodology: LakeGrade methodology.
Watch South Reservoir water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
No clarity data. Chlorophyll-a: 2.5 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 2.5 µg/L | A |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near South Reservoir
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Top-rated places to stay near South Reservoir
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Fishing South Reservoir
Location
County Ranking
Ranked #1 of 15 lakes in Middlesex County
Nearby Lakes in Middlesex County
Explore South Reservoir across LakeGrade
Species activity outlook by water temperature and season
Where to stay at Massachusetts's top lakes, each with its grade
Low nutrients, clear water, excellent for swimming
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More Massachusetts Lake Rankings
Top 25 by overall water quality score
Top 25 by Secchi water clarity
Grade A/B + low algae filter
Panfish-rich, public access
Full state directory
Other Grade A Lakes in Massachusetts
Oligotrophic Lakes in Massachusetts
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2017-09-14
Monitoring stations: 1