Sylvan Lake
Sylvan Lake in Monmouth County, New Jersey has a water quality grade of F (Algae-prone). Water clarity: 1.8 ft visibility. Phosphorus: 82.9 µg/L. Chlorophyll-a (algae): 31.6 µg/L.
- Clarity
- 1.8 ft
- Type
- Hypereutrophic
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Sylvan Lake →
Sylvan Lake is a highly nutrient-loaded hypereutrophic lake in Monmouth County, New Jersey. Water quality is graded F based on 2 sampling years through 2021. 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. 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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.8 ft of visibility. Phosphorus level: 82.9 µg/L. Chlorophyll-a: 31.6 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.8 ft | Not graded |
| Phosphorus | 82.9 µg/L | Poor |
| Chlorophyll-a (Algae) | 31.6 µg/L | Poor |
| Trophic State Index (TSI) | 67 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay 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 grade measures nutrients and algae, not lodging — cabins and rentals around Sylvan Lake are listed below.
Top-rated places to stay near Sylvan Lake
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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
Source: EPA ATTAINS assessment unit NJ02030104090090-01 · Official waterbody report · Matched by proximity (2.02 km)
County Ranking
Ranked #4 of 4 lakes in Monmouth County
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. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sylvan Lake?
- Sylvan Lake in Monmouth County, New Jersey has a water quality grade of F (Algae-prone). 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?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Sylvan Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 31.6 µg/L. Always check local health department advisories before swimming.
Explore Sylvan Lake across LakeGrade
More New Jersey Lake Rankings
Other Grade F Lakes in New Jersey
Hypereutrophic Lakes in New Jersey
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)
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