Toisnot Reservoir
Wilson County, North CarolinaView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- #2 of 4 in the county
Toisnot Reservoir in Wilson County, North Carolina has a water quality grade of D (Nutrient-rich). Water clarity: 2.3 ft visibility. Phosphorus: 90 µg/L. Chlorophyll-a (algae): 18 µg/L.
- Clarity
- 2.3 ft
- Type
- Eutrophic
- Trend
- ↓ Declining
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Stays near Toisnot Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Toisnot Reservoir in Wilson 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 Toisnot Reservoir are listed below.
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Toisnot Reservoir is a productive, nutrient-rich eutrophic lake in Wilson County, North Carolina. Water quality is graded D based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Compared to the 3 other monitored lakes in Wilson County, Toisnot Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2025-09-10. 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. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2.3 ft of visibility. Phosphorus 90 µg/L. Chlorophyll-a 18 µg/L. TSI 64. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.3 ft | Not graded |
| Phosphorus | 90 µg/L | Poor |
| Chlorophyll-a (Algae) | 18 µg/L | Fair |
| Trophic State Index (TSI) | 64 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Toisnot Reservoir
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | → Stable | -1 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +4.28 µg/L/yr | 2 |
County Ranking
Ranked #2 of 4 lakes in Wilson County
Nearby Lakes in Wilson County
Frequently asked questions about Toisnot Reservoir
Where is Toisnot Reservoir?
- Toisnot Reservoir is a lake in Wilson 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 Toisnot Reservoir?
- Toisnot Reservoir in Wilson County, North Carolina has a water quality grade of D (Nutrient-rich). Water clarity: 2.3 ft visibility. Phosphorus: 90 µg/L. Chlorophyll-a (algae): 18 µg/L.
Is Toisnot Reservoir safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Toisnot Reservoir 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
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 D Lakes in North Carolina
Eutrophic Lakes in North Carolina
Where this data comes from
53 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
21NC03WQ53 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.