Grenloch Lake
Grenloch Lake in Gloucester County, New Jersey has a water quality grade of A (Excellent). Water clarity: 4.8 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Surface area: 21 acres.
- Clarity
- 4.8 ft
- Area
- 21 acres
- Type
- Mesotrophic
Grenloch Lake is a 21-acre mesotrophic lake in Gloucester County, New Jersey. Water quality is graded A based on 2 sampling years through 2024. Compared to the 2 other monitored lakes in Gloucester County, Grenloch Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-10-31. 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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Murky, only visible to about 4.8 ft. Phosphorus level: 30 µg/L. Chlorophyll-a: 4.3 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.8 ft | Not graded |
| Phosphorus | 30 µg/L | Good |
| Chlorophyll-a (Algae) | 4.3 µg/L | Good |
| Trophic State Index (TSI) | 51 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Grenloch Lake
Compare lakeside cabins, hotels, and vacation rentals near Grenloch Lake in Gloucester 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 Grenloch Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 21 acres |
No bathymetric survey has been published for Grenloch Lake, so its depth is not documented here.
Fishing Grenloch Lake
Reservoir Info (USACE NID)
Grenloch Lake is a man-made reservoir impounded by the Grenloch Lake Dam (completed 1907), built primarily for recreation on the South Branch Timber Creek; earth-type dam, 21 ft tall and 250 ft long.
- Surface area
- 21 ac
- Normal storage
- 92 ac-ft
- Max storage
- 272 ac-ft
- Drainage area
- 14.6 sq mi
- Hazard class
- Significant
- Owner
- Township of Washington
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID NJ00402 · Operator website
EPA Impairment Status
Grenloch 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 NJ02040202120040-01 · Official waterbody report · Matched by proximity (1.14 km)
County Ranking
Ranked #1 of 3 lakes in Gloucester County
Nearby Lakes in Gloucester County
Frequently asked questions about Grenloch Lake
Where is Grenloch Lake?
- Grenloch Lake is a lake in Gloucester County, New Jersey. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Grenloch Lake?
- Grenloch Lake in Gloucester County, New Jersey has a water quality grade of A (Excellent). Water clarity: 4.8 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Surface area: 21 acres.
Is Grenloch Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Grenloch Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.3 µg/L. Always check local health department advisories before swimming.
Explore Grenloch Lake across LakeGrade
More New Jersey Lake Rankings
Other Grade A Lakes in New Jersey
Mesotrophic Lakes in New Jersey
Where this data comes from
27 measurements from 2 monitoring stations, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- NJDEP Bureau of Freshwater and Biological Monitoring
NJDEP_BFBM27 samples · 2024
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database