Franklin County, Virginia · Water Quality Report Card
Smith Mountain Lake
Smith Mountain Lake in Franklin County, Virginia is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7 ft visibility.
- Clarity
- 7 ft
- Mean depth
- ~65 ft est.
- Type
- Mesotrophic
- Trend
- ↑ Improving
Smith Mountain Lake is a mesotrophic lake in Franklin County, Virginia with an estimated average depth of about 65 feet. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Virginia DEQ, last sampled 2017-07-15. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not rated for swimming — there is not enough monitoring data to judge this lake
Water Quality Grade: Not rated
Moderate clarity, visible to about 7 ft. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7 ft | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~65 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Virginia has not published bathymetry for Smith Mountain Lake.
Where to stay near Smith Mountain Lake
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Fishing Smith Mountain Lake
Water Quality Trend: ↑ Improving
Based on 15 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.064 m/yr | 15 |
| Phosphorus | ↑ Improving | -0.32 µg/L/yr | 15 |
| Chlorophyll-a | → Stable | -0.04 µg/L/yr | 15 |
Location
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Rockbridge County · Not rated
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Mesotrophic Lakes in Virginia
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Where this data comes from
2 measurements from 1 monitoring station, 2015–2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS2 samples · 2015–2017
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2017-07-15
Monitoring stations: 1