By Fox Island Lake
Passaic County, New Jersey1,733 acresView mapDirections
NJDEP publishes the water-quality measurements for By Fox Island Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Mercury
By Fox Island Lake in Passaic County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 43.5 µg/L. Surface area: 1733 acres.
By Fox Island Lake is a 1,733-acre highly nutrient-loaded hypereutrophic lake in Passaic County, New Jersey. Compared to the 5 other monitored lakes in Passaic County, By Fox Island Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-19. Methodology: how these readings are compared.
What By Fox Island Lake is good for
From access and monitoring records, not editorial picks.
- Big water1,733 acres
Swimming conditions
Readings onlyAlgae risk
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. By Fox Island Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pH / acidity, temperature. Check local advisories before you swim.
Whether By Fox Island Lake is safe to swim in today is a call for the New Jersey Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for By Fox Island Lake
These are the measurements NJDEP publishes for By Fox Island Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 39 µg/L. Chlorophyll-a 43.5 µg/L. TSI 62.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 39µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 43.5µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 62 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about By Fox Island Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
1,733 acres
No bathymetric survey has been published for By Fox Island Lake, so its depth is not documented here.
Stays via Stay22
Stays near By Fox Island Lake
Compare lakeside cabins, hotels, and vacation rentals near By Fox Island Lake in Passaic 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 readings cover nutrients and algae, not lodging. Cabins and rentals around By Fox Island Lake are listed below.
Top-rated places to stay near By Fox Island Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Follow By Fox Island Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing By Fox Island Lake
Reservoir Info (USACE NID)
By Fox Island Lake is a man-made reservoir impounded by the Greenwood Lake Dam (completed 1928), built primarily for recreation on the Wanaque River; concrete-type dam, 17 ft tall and 270 ft long.
- Surface area
- 1,733 ac
- Normal storage
- 13,269 ac-ft
- Drainage area
- 27.1 sq mi
- Hazard class
- High
- Owner
- Division of Parks and Forestry
Source: USACE National Inventory of Dams, NID ID NJ00187 · Operator website · Matched by proximity (0.6 km)
EPA Impairment Status
By Fox Island Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NJ02030103070030-01 · Official waterbody report
Nearby Lakes in Passaic County
Frequently asked questions about By Fox Island Lake
Where is By Fox Island Lake?
- By Fox Island Lake is a lake in Passaic County, New Jersey. Its water-quality measurements are published by NJDEP and shown on this page as reported.
What is the water quality of By Fox Island Lake?
- By Fox Island Lake in Passaic County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 43.5 µg/L. Surface area: 1733 acres.
Is By Fox Island Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. By Fox Island Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pH / acidity, temperature. Check local advisories before you swim.
Explore By Fox Island Lake across LakeQuality
More lakes in New Jersey
Other Lakes in New Jersey
Hypereutrophic Lakes in New Jersey
Where this data comes from
68 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Montclair State University
NJ_MSU68 samples · 2024–2025
Analytical methods
- 4500 P B ~ Phosphorus, sample preparation method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database