Lake Ben Johnson
Orange County, North CarolinaView mapDirections
NC DEQ publishes the water-quality measurements for Lake Ben Johnson. Here is what has been measured.
- Mesotrophic
Lake Ben Johnson in Orange County, North Carolina has water-quality measurements published by NC DEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 6.5 µg/L.
Lake Ben Johnson is a mesotrophic lake in Orange County, North Carolina. Overall water quality is improving over recent sampling years. Compared to the 6 other monitored lakes in Orange County, Lake Ben Johnson ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2025-09-11. Methodology: how these readings are compared.
Swimming conditions
Readings onlyModerate 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. Check local advisories before you swim.
Whether Lake Ben Johnson is safe to swim in today is a call for the North Carolina Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Ben Johnson
These are the measurements NC DEQ publishes for Lake Ben Johnson, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 3.3 ft of visibility. Phosphorus 50 µg/L. Chlorophyll-a 6.5 µg/L. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 50µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 6.5µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 56 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Lake Ben Johnson
Answers come straight from the public measurements and survey records on this page.
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Fishing Lake Ben Johnson
Water quality readings over time
2 seasons of samples on record (2020–2025). Calling a direction takes at least 4 years of the same measurement.
Phosphorus
Stable0 µg/L/yr2 years
Chlorophyll-a
Improving-2.12 µg/L/yr2 years
Reservoir Info (USACE NID)
Lake Ben Johnson is a man-made reservoir impounded by the Johnson Lake Dam (completed 1955), built primarily for other on the Eno River; earth-type dam, 15 ft tall and 110 ft long.
- Drainage area
- 59.8 sq mi
- Hazard class
- Significant
- Owner
- Town of Hillsborough
All listed purposes: Other;Water Supply.
Source: USACE National Inventory of Dams, NID ID NC00774 · Operator website
Nearby Lakes in Orange County
Frequently asked questions about Lake Ben Johnson
Where is Lake Ben Johnson?
- Lake Ben Johnson is a lake in Orange County, North Carolina. Its water-quality measurements are published by NC DEQ and shown on this page as reported.
What is the water quality of Lake Ben Johnson?
- Lake Ben Johnson in Orange County, North Carolina has water-quality measurements published by NC DEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 6.5 µg/L.
Is Lake Ben Johnson safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Lake Ben Johnson across LakeQuality
More lakes in North Carolina
Other Lakes in North Carolina
Mesotrophic Lakes in North Carolina
Where this data comes from
41 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Carolina Dept of Environmental Quality NCDEQ-DWR WQX
21NC03WQ41 samples · 2020–2025
Analytical methods
- WSSSOP
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
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.