Lake Johnson
Wake County, North Carolina148 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- #1 of 14 in the county
- 44 ft max depth
Lake Johnson in Wake County, North Carolina has a water quality grade of D (Nutrient-rich). Water clarity: 3 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 23 µg/L. Surface area: 147.5 acres.
- Clarity
- 3 ft
- Max depth
- ~44 ft est.
- Area
- 148 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
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 grade measures nutrients and algae, not lodging — cabins and rentals around Lake Johnson are listed below.
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Watch Lake Johnson’s letter
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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. Water quality is graded D based on 2 sampling years through 2025. 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. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
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 D is nutrients and algae, 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.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 3 ft of visibility. Phosphorus 40 µg/L. Chlorophyll-a 23 µg/L. TSI 60. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 40 µg/L | Poor |
| Chlorophyll-a (Algae) | 23 µg/L | Poor |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
→ Lake Johnson water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~44 ft est. |
| Average Depth | ~14 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
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.
Fishing Lake Johnson
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +4 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +1.5 µg/L/yr | 2 |
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NC27-34-(1.5) · Official waterbody report · Matched by proximity (0.27 km)
County Ranking
Ranked #1 of 14 lakes in Wake County
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. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Johnson?
- Lake Johnson in Wake County, North Carolina has a water quality grade of D (Nutrient-rich). 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?
- The D is nutrients and algae, 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
Species activity outlook by water temperature and season
Where to stay at North Carolina's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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Other Grade D Lakes in North Carolina
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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)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)