Lake Johnson
Wake County, North Carolina148 acresView mapDirections
NC DEQ publishes the water-quality measurements for Lake Johnson. Here is what has been measured.
- Eutrophic
- Impaired · PCBs
- 44 ft max depth
Lake Johnson in Wake County, North Carolina has water-quality measurements published by NC DEQ, shown here as reported. Water clarity: 3 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 23 µg/L. Surface area: 147.5 acres.
Lake Johnson is a 148-acre productive, nutrient-rich eutrophic lake in Wake County, North Carolina with an estimated average depth of about 44 feet. Overall water quality is declining over recent sampling years. Compared to the 13 other monitored lakes in Wake County, Lake Johnson ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2025-10-16. Methodology: how these readings are compared.
Swimming conditions
Readings onlyAlgae risk
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. Lake Johnson is listed impaired under Clean Water Act §303(d) (IR 5A) for pCBs. Check local advisories before you swim.
Whether Lake 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 Johnson
These are the measurements NC DEQ publishes for Lake 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 ft of visibility. Phosphorus 40 µg/L. Chlorophyll-a 23 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 40µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 23µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Johnson
Answers come straight from the public measurements and survey records on this page.
→ Lake Johnson water level: the live USGS gauge reading
Lake Details
Max depth
~44 ft est.
Surface area
148 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Carolina has not published bathymetry for Lake Johnson.
Lake Size & Watershed
Watershed (drainage) area
7 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.9 mi
HydroLAKES / HydroSHEDS
Elevation
367 ft
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.
Stays via Stay22
Stays near Lake Johnson
Compare lakeside cabins, hotels, and vacation rentals near Lake Johnson in Wake County, North Carolina — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Lake Johnson are listed below.
Top-rated places to stay near Lake Johnson
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at North Carolina’s top lakes →
Follow Lake Johnson’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Lake 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
Worsening+4 µg/L/yr2 years
Chlorophyll-a
Worsening+1.5 µg/L/yr2 years
Reservoir Info (USACE NID)
Lake Johnson is a man-made reservoir impounded by the Lake Johnson Dam (completed 1914), built primarily for water supply on the Walnut Creek; earth-type dam, 40 ft tall and 779 ft long.
- Surface area
- 147.5 ac
- Normal storage
- 2,570 ac-ft
- Max storage
- 3,090 ac-ft
- Drainage area
- 6.88 sq mi
- Hazard class
- High
- Owner
- City of Raleigh Public Utilities Department
Source: USACE National Inventory of Dams, NID ID NC00862 · Operator website
EPA Impairment Status
Lake Johnson is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NC27-34-(1.5) · Official waterbody report
Nearby Lakes in Wake County
Frequently asked questions about Lake Johnson
Where is Lake Johnson?
- Lake Johnson is a lake in Wake 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 Johnson?
- Lake Johnson in Wake County, North Carolina has water-quality measurements published by NC DEQ, shown here as reported. Water clarity: 3 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 23 µg/L. Surface area: 147.5 acres.
Is Lake Johnson safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Johnson is listed impaired under Clean Water Act §303(d) (IR 5A) for pCBs. Check local advisories before you swim.
How deep is Lake Johnson?
- No published bathymetric survey covers Lake Johnson, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 44 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 147.5 acres.
Explore Lake Johnson across LakeQuality
More lakes in North Carolina
Other Lakes in North Carolina
Eutrophic Lakes in North Carolina
Where this data comes from
56 measurements from 2 monitoring stations, 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
21NC03WQ56 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 (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)