Lake Twitty
Union County, North Carolina327 acresView mapDirections
Nutrients and algae run well above the regional average.
↓ down from D at the last regrade
- Hypereutrophic
- #3 of 3 in the county
- 43 ft max depth
- Limited data
Lake Twitty in Union County, North Carolina has a water quality grade of F (Algae-prone). Phosphorus: 80 µg/L. Chlorophyll-a (algae): 49 µg/L. Surface area: 327 acres.
- Max depth
- ~43 ft est.
- Area
- 327 acres
- Type
- Hypereutrophic
Stays via Stay22
Stays near Lake Twitty
Compare lakeside cabins, hotels, and vacation rentals near Lake Twitty in Union 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 Twitty are listed below.
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Watch Lake Twitty’s letter
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Lake Twitty is a 327-acre highly nutrient-loaded hypereutrophic lake in Union County, North Carolina with an estimated average depth of about 43 feet. Water quality is graded F based on 2 sampling years through 2021. Compared to the 2 other monitored lakes in Union County, Lake Twitty ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2021-09-29. Grade methodology: LakeQuality methodology.
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 F is nutrients and algae, not a swimming clearance. Lake Twitty is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
No clarity data. Phosphorus 80 µg/L. Chlorophyll-a 49 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 80 µg/L | Poor |
| Chlorophyll-a (Algae) | 49 µg/L | Poor |
| Trophic State Index (TSI) | 68 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~43 ft est. |
| Average Depth | ~9 ft est. |
| Surface Area | 327 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 Twitty.
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 Twitty
Reservoir Info (USACE NID)
Lake Twitty is a man-made reservoir impounded by the Twitty Dam (completed 1973), built primarily for water supply on the Stewarts Creek; earth-type dam, 60 ft tall and 790 ft long.
- Surface area
- 327 ac
- Normal storage
- 9,600 ac-ft
- Max storage
- 17,000 ac-ft
- Drainage area
- 35.21 sq mi
- Hazard class
- High
- Owner
- City of Monroe
Source: USACE National Inventory of Dams, NID ID NC00532 · Operator website
EPA Impairment Status
Lake Twitty is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NC13-17-36-9-(4.5) · Official waterbody report · Matched by proximity (0.7 km)
County Ranking
Ranked #3 of 3 lakes in Union County
Nearby Lakes in Union County
Frequently asked questions about Lake Twitty
Where is Lake Twitty?
- Lake Twitty is a lake in Union County, North Carolina. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Twitty?
- Lake Twitty in Union County, North Carolina has a water quality grade of F (Algae-prone). Phosphorus: 80 µg/L. Chlorophyll-a (algae): 49 µg/L. Surface area: 327 acres.
Is Lake Twitty safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Lake Twitty is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
How deep is Lake Twitty?
- No published bathymetric survey covers Lake Twitty, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 43 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 327 acres.
Explore Lake Twitty across LakeQuality
Species activity outlook by water temperature and season
Where to stay at North Carolina's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Where this data comes from
48 measurements from 3 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Carolina Dept of Environmental Quality NCDEQ-DWR WQX
21NC03WQ48 samples · 2021
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (3)
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)