Duhernal Lake
Duhernal Lake in Middlesex County, New Jersey has a water quality grade of C (Fair). Water clarity: 4.6 ft visibility. Phosphorus: 64 µg/L. Chlorophyll-a (algae): 4.4 µg/L. Surface area: 195 acres.
- Clarity
- 4.6 ft
- Area
- 195 acres
- Type
- Mesotrophic
Duhernal Lake is a 195-acre mesotrophic lake in Middlesex County, New Jersey. Water quality is graded C based on 2 sampling years through 2023. Compared to the 2 other monitored lakes in Middlesex County, Duhernal Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-11-21. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 4.6 ft. Phosphorus level: 64 µg/L. Chlorophyll-a: 4.4 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.6 ft | Not graded |
| Phosphorus | 64 µg/L | Poor |
| Chlorophyll-a (Algae) | 4.4 µg/L | Good |
| Trophic State Index (TSI) | 55 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Duhernal Lake
Compare lakeside cabins, hotels, and vacation rentals near Duhernal Lake in Middlesex County, New Jersey — 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.
Top-rated places to stay near Duhernal Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 195 acres |
No bathymetric survey has been published for Duhernal Lake, so its depth is not documented here.
Fishing Duhernal Lake
Reservoir Info (USACE NID)
Duhernal Lake is a man-made reservoir impounded by the Duhernal Dam (completed 1939), built primarily for recreation on the South River; earth-type dam, 13 ft tall and 878 ft long.
- Surface area
- 195 ac
- Normal storage
- 780 ac-ft
- Max storage
- 1,520 ac-ft
- Drainage area
- 94.6 sq mi
- Hazard class
- Significant
- Owner
- Borough of Sayreville
Source: USACE National Inventory of Dams, NID ID NJ00381 · Operator website
EPA Impairment Status
Duhernal Lake 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 NJ02030105160030-01 · Official waterbody report · Matched by proximity (1.53 km)
County Ranking
Ranked #2 of 3 lakes in Middlesex County
Nearby Lakes in Middlesex County
Frequently asked questions about Duhernal Lake
Where is Duhernal Lake?
- Duhernal Lake is a lake in Middlesex County, New Jersey. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Duhernal Lake?
- Duhernal Lake in Middlesex County, New Jersey has a water quality grade of C (Fair). Water clarity: 4.6 ft visibility. Phosphorus: 64 µg/L. Chlorophyll-a (algae): 4.4 µg/L. Surface area: 195 acres.
Is Duhernal Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Duhernal Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 4.4 µg/L. Always check local health department advisories before swimming.
Explore Duhernal Lake across LakeGrade
More New Jersey Lake Rankings
Other Grade C Lakes in New Jersey
Mesotrophic Lakes in New Jersey
Where this data comes from
219 measurements from 4 monitoring stations, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- NJDEP Bureau of Freshwater and Biological Monitoring
NJDEP_BFBM219 samples · 2022–2023
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2120 B ~ Color in Water by Visual Comparison
Monitoring station identifiers (4)
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