Lake Sidney Lanier
Forsyth County, GeorgiaView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- Impaired · Algal growth
- #1 of 3 in the county
- Public access
Lake Sidney Lanier in Forsyth County, Georgia has a water quality grade of C (Fair). Water clarity: 9.2 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 7.7 µg/L.
- Clarity
- 9.2 ft
- Type
- Eutrophic
- Phosphorus
- 20 µg/L
- Chlorophyll-a
- 7.7 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Lake Sidney Lanier
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Watch Lake Sidney Lanier’s letter
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Lake Sidney Lanier is a productive, nutrient-rich eutrophic lake in Forsyth County, Georgia. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 7 public boat landings. Compared to the 2 other monitored lakes in Forsyth County, Lake Sidney Lanier ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Georgia EPD, last sampled 2025-10-07. Grade methodology: LakeQuality methodology.
What Lake Sidney Lanier is good for
From access and monitoring records, not editorial picks.
- Boat launch7 documented ramps
Swimming Safety
Grade onlyModerate
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. Lake Sidney Lanier is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, pCBs. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 9.2 ft. Phosphorus 20 µg/L. Chlorophyll-a 7.7 µg/L. TSI 48. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.2 ft | Not graded |
| Phosphorus | 20 µg/L | Fair |
| Chlorophyll-a (Algae) | 7.7 µg/L | Fair |
| Trophic State Index (TSI) | 48 | Eutrophic |
High nutrients, frequent algae, reduced clarity
→ Lake Sidney Lanier water level: the live USGS gauge reading
Recreation & Access
- Old FederalPublic
- Old Federal Day UsePublic
- Vanns TavernPublic
- Commodore Drive - 1Public
- Commodore Drive - 2Public
- Sunrise Cove MarinaSemi-private
Showing 6 of 7 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Sidney Lanier
Water Quality Trend: ↓ Declining
Based on 14 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.005 m/yr | 14 |
| Phosphorus | → Stable | 0 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.55 µg/L/yr | 14 |
EPA Impairment Status
Lake Sidney Lanier is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit GAR031300010819 · Official waterbody report · Matched by proximity (1.76 km)
County Ranking
Ranked #1 of 3 lakes in Forsyth County
Nearby Lakes in Forsyth County
Frequently asked questions about Lake Sidney Lanier
Where is Lake Sidney Lanier?
- Lake Sidney Lanier is a lake in Forsyth County, Georgia. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Sidney Lanier?
- Lake Sidney Lanier in Forsyth County, Georgia has a water quality grade of C (Fair). Water clarity: 9.2 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 7.7 µg/L.
Is Lake Sidney Lanier safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Lake Sidney Lanier is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, pCBs. Check local advisories before you swim.
Are there boat ramps on Lake Sidney Lanier?
- Lake Sidney Lanier has 7 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Old Federal, Old Federal Day Use, Vanns Tavern, Commodore Drive - 1, among others. Public access is listed as yes.
Explore Lake Sidney Lanier across LakeQuality
7.2 mi away · cable-pulled, no boat wake
Species activity outlook by water temperature and season
Where to stay at Georgia's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
Georgia's cleanest and most-polluted lakes, ranked
Planning a trip around Chattahoochee River?
Lake Sidney Lanier is about 26 miles from Chattahoochee River National Recreation Area. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Chattahoochee River →More Georgia Lake Rankings
Other Grade C Lakes in Georgia
Eutrophic Lakes in Georgia
Where this data comes from
900 measurements from 4 monitoring stations, 2012–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Georgia DNR Environmental Protection Division
21GAEPD_WQX900 samples · 2012–2025
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Turbidity by Nephelometry
Monitoring station identifiers (4)
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
Named boat-access points from the USGS National Boat Ramps inventory