Lake Sidney Lanier is a mesotrophic lake in Forsyth County, Georgia. Water quality is graded C based on 1 sampling years through 2025. Compared to the 2 other monitored lakes in Forsyth County, Lake Sidney Lanier ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Georgia DNR, last sampled 2025-10-01. 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 9.2 ft. Chlorophyll-a: 7.7 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.2 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 7.7 µg/L | C |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lake Sidney Lanier
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Location
County Ranking
Ranked #2 of 3 lakes in Forsyth County
Nearby Lakes in Forsyth County
Explore Lake Sidney Lanier across LakeGrade
More Georgia Lake Rankings
Other Grade C Lakes in Georgia
Mesotrophic Lakes in Georgia
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-01
Monitoring stations: 2