Cool Branch Lake
Franklin County, VirginiaView mapDirections
Virginia DEQ publishes the water-quality measurements for Cool Branch Lake. Here is what has been measured.
- Mesotrophic
- Impaired · PCBs
- Public access
Cool Branch Lake in Franklin County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 10.5 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.1 µg/L.
Cool Branch Lake is a mesotrophic lake in Franklin County, Virginia. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 12 other monitored lakes in Franklin County, Cool Branch Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Virginia DEQ, last sampled 2026-06-16. Methodology: how these readings are compared.
What Cool Branch Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Cool Branch Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pCBs. Check local advisories before you swim.
Whether Cool Branch Lake is safe to swim in today is a call for the Virginia Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cool Branch Lake
These are the measurements Virginia DEQ publishes for Cool Branch Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10.5 ft. Phosphorus 10 µg/L. Chlorophyll-a 2.1 µg/L. TSI 39.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 10µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.1µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 39 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Cool Branch Lake
Answers come straight from the public measurements and survey records on this page.
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Stays near Cool Branch Lake
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Fishing Cool Branch Lake
Water Quality Trend: Improving
Based on 15 years of monitoring (2012–2026).
Water clarity
Improving15 years
Phosphorus
Improving-0.27 µg/L/yr14 years
Chlorophyll-a
Improving-0.07 µg/L/yr14 years
EPA Impairment Status
Cool Branch Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit VAW-L10L_COA01A10 · Official waterbody report
Nearby Lakes in Franklin County
Frequently asked questions about Cool Branch Lake
Where is Cool Branch Lake?
- Cool Branch Lake is a lake in Franklin County, Virginia. Its water-quality measurements are published by Virginia DEQ and shown on this page as reported.
What is the water quality of Cool Branch Lake?
- Cool Branch Lake in Franklin County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 10.5 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.1 µg/L.
Is Cool Branch Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Cool Branch Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pCBs. Check local advisories before you swim.
Can I fish at Cool Branch Lake?
- Public access to Cool Branch Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Virginia's fish and wildlife agency, so check its current regulations before you go.
Explore Cool Branch Lake across LakeQuality
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Where this data comes from
642 measurements from 1 monitoring station, 2012–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- VIRGINIA DEPARTMENT OF ENVIRONMENTAL QUALITY
21VASWCB642 samples · 2012–2026
Analytical methods
- Tyler, John. 1968. The secchi disk, Limnology and Oceanograpy, 13(1):1-6.
- Total Phosphorus After Block Digestion
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 446.0 ~ EPA; Chlorophylls and Pheopigments in Phytoplankton by Spectrophotometry
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database