Sylvan Lake
Monmouth County, New JerseyView mapDirections
NJDEP publishes the water-quality measurements for Sylvan Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
Sylvan Lake in Monmouth County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 82.9 µg/L. Chlorophyll-a (algae): 31.6 µg/L.
Sylvan Lake is a highly nutrient-loaded hypereutrophic lake in Monmouth County, New Jersey. Compared to the 3 other monitored lakes in Monmouth County, Sylvan Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-10-20. Methodology: how these readings are compared.
Swimming conditions
Readings onlyBacteria advisory
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. Sylvan Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal). Check local advisories before you swim.
Whether Sylvan 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 Sylvan Lake
These are the measurements NJDEP publishes for Sylvan Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.8 ft of visibility. Phosphorus 82.9 µg/L. Chlorophyll-a 31.6 µg/L. TSI 67.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 82.9µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 31.6µg/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. | 67 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Sylvan Lake
Answers come straight from the public measurements and survey records on this page.
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Stays near Sylvan Lake
Compare lakeside cabins, hotels, and vacation rentals near Sylvan Lake in Monmouth 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 Sylvan Lake are listed below.
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Fishing Sylvan Lake
EPA Impairment Status
Sylvan 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, Recreation.
Source: EPA ATTAINS assessment unit NJ02030104090090-01 · Official waterbody report
Nearby Lakes in Monmouth County
Frequently asked questions about Sylvan Lake
Where is Sylvan Lake?
- Sylvan Lake is a lake in Monmouth County, New Jersey. Its water-quality measurements are published by NJDEP and shown on this page as reported.
What is the water quality of Sylvan Lake?
- Sylvan Lake in Monmouth County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 82.9 µg/L. Chlorophyll-a (algae): 31.6 µg/L.
Is Sylvan Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Sylvan Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal). Check local advisories before you swim.
Explore Sylvan Lake across LakeQuality
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Where this data comes from
55 measurements from 2 monitoring stations, 2020–2021. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- NJDEP Bureau of Freshwater and Biological Monitoring
NJDEP_BFBM55 samples · 2020–2021
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (2)
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