Asu Lake
Watauga County, North Carolina22 acresView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- #2 of 3 in the county
- Limited data
Asu Lake in Watauga County, North Carolina has a water quality grade of C (Fair). Water clarity: 12.3 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 5.2 µg/L. Surface area: 22 acres.
- Clarity
- 12.3 ft
- Area
- 22 acres
- Type
- Mesotrophic
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Watch Asu Lake’s letter
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Asu Lake is a 22-acre mesotrophic lake in Watauga County, North Carolina. Water quality is graded C based on 2 sampling years through 2023. Compared to the 2 other monitored lakes in Watauga County, Asu Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2023-09-11. Grade methodology: LakeQuality methodology.
What Asu Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12.3 ft of visibility
Swimming Safety
Grade onlyLimited data
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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Good clarity, visible to about 12.3 ft. Phosphorus 30 µg/L. Chlorophyll-a 5.2 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.3 ft | Not graded |
| Phosphorus | 30 µg/L | Fair |
| Chlorophyll-a (Algae) | 5.2 µg/L | Good |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 22 acres |
No bathymetric survey has been published for Asu Lake, so its depth is not documented here.
Fishing Asu Lake
Reservoir Info (USACE NID)
Asu Lake is a man-made reservoir impounded by the Asu-Norris Branch Dam (completed 1974), built primarily for water supply on the Norris Branch; earth-type dam, 112 ft tall and 480 ft long.
- Surface area
- 22 ac
- Normal storage
- 564 ac-ft
- Max storage
- 762 ac-ft
- Drainage area
- 0.34 sq mi
- Hazard class
- High
- Owner
- Appalachian State University
Source: USACE National Inventory of Dams, NID ID NC01524 · Operator website · Matched by proximity (0.08 km)
County Ranking
Ranked #2 of 3 lakes in Watauga County
Nearby Lakes in Watauga County
Frequently asked questions about Asu Lake
Where is Asu Lake?
- Asu Lake is a lake in Watauga County, North Carolina. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Asu Lake?
- Asu Lake in Watauga County, North Carolina has a water quality grade of C (Fair). Water clarity: 12.3 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 5.2 µg/L. Surface area: 22 acres.
Is Asu Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Asu Lake across LakeQuality
2 documented falls within 24.6 mi, nearest Elk River Falls
Species activity outlook by water temperature and season
Where to stay at North Carolina's top lakes, each with its grade
Moderate nutrients, good water quality
North Carolina's cleanest and most-polluted lakes, ranked
More North Carolina Lake Rankings
Ranked by overall water quality grade
Top 25 by Secchi water clarity
Grade A/B + low algae filter
Panfish-rich, public access
Full state directory
Other Grade C Lakes in North Carolina
Mesotrophic Lakes in North Carolina
Where this data comes from
20 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Carolina Dept of Environmental Quality NCDEQ-DWR WQX
21NC03WQ20 samples · 2023
Analytical methods
- WSSSOP
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (1)
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.