Unl Lake
Unl Lake in Sussex County, New Jersey has a water quality grade of D (Nutrient-rich). Water clarity: 3.3 ft visibility. Phosphorus: 43.1 µg/L. Chlorophyll-a (algae): 12.9 µg/L. Surface area: 4 acres.
- Clarity
- 3.3 ft
- Area
- 4 acres
- Type
- Eutrophic
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Unl Lake →
Unl Lake is a 4-acre productive, nutrient-rich eutrophic lake in Sussex County, New Jersey. Water quality is graded D based on 2 sampling years through 2021. Compared to the 17 other monitored lakes in Sussex County, Unl Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-11-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria advisory
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 3.3 ft of visibility. Phosphorus level: 43.1 µg/L. Chlorophyll-a: 12.9 µg/L. Trophic State Index: 58.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.3 ft | Not graded |
| Phosphorus | 43.1 µg/L | Poor |
| Chlorophyll-a (Algae) | 12.9 µg/L | Fair |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Unl Lake
Compare lakeside cabins, hotels, and vacation rentals near Unl Lake in Sussex 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Unl Lake are listed below.
Top-rated places to stay near Unl Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 4 acres |
No bathymetric survey has been published for Unl Lake, so its depth is not documented here.
Fishing Unl Lake
Reservoir Info (USACE NID)
Unl Lake is a man-made reservoir impounded by the Branchville Reservoir Dam (completed 1934), built primarily for water supply on the Dry Brook; earth-type dam, 22 ft tall and 690 ft long.
- Surface area
- 4 ac
- Normal storage
- 21 ac-ft
- Drainage area
- 1 sq mi
- Hazard class
- Significant
- Owner
- Borough of Branchville
Source: USACE National Inventory of Dams, NID ID NJ00009 · Operator website · Matched by proximity (0.85 km)
EPA Impairment Status
Unl Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NJ02020007020010-01 · Official waterbody report · Matched by proximity (2.33 km)
County Ranking
Ranked #13 of 18 lakes in Sussex County
Nearby Lakes in Sussex County
Frequently asked questions about Unl Lake
Where is Unl Lake?
- Unl Lake is a lake in Sussex County, New Jersey. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Unl Lake?
- Unl Lake in Sussex County, New Jersey has a water quality grade of D (Nutrient-rich). Water clarity: 3.3 ft visibility. Phosphorus: 43.1 µg/L. Chlorophyll-a (algae): 12.9 µg/L. Surface area: 4 acres.
Is Unl Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Unl Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 12.9 µg/L. Always check local health department advisories before swimming.
Explore Unl Lake across LakeGrade
More New Jersey Lake Rankings
Other Grade D Lakes in New Jersey
Eutrophic Lakes in New Jersey
Where this data comes from
22 measurements from 3 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- NJDEP Bureau of Freshwater and Biological Monitoring
NJDEP_BFBM22 samples · 2021
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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