Hopatcong A Lake
Sussex County, New JerseyView mapDirections
NJDEP publishes the water-quality measurements for Hopatcong A Lake. Here is what has been measured.
- Impaired · Mercury
- Limited data
Hopatcong A Lake in Sussex County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 4.3 ft visibility.
Hopatcong A Lake is a lake in Sussex County, New Jersey.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-09-24. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Hopatcong A Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pesticides, pH / acidity, pCBs, temperature. Check local advisories before you swim.
Whether Hopatcong A 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 Hopatcong A Lake
These are the measurements NJDEP publishes for Hopatcong A Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.3 ft. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 56 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Hopatcong A Lake
Answers come straight from the public measurements and survey records on this page.
Stays via Stay22
Stays near Hopatcong A Lake
Compare lakeside cabins, hotels, and vacation rentals near Hopatcong A 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.
Top-rated places to stay near Hopatcong A 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 Hopatcong A Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Hopatcong A Lake
EPA Impairment Status
Hopatcong A 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 NJ02040105150020-01 · Official waterbody report
Nearby Lakes in Sussex County
Frequently asked questions about Hopatcong A Lake
Where is Hopatcong A Lake?
- Hopatcong A Lake is a lake in Sussex County, New Jersey. Its water-quality measurements are published by NJDEP and shown on this page as reported.
What is the water quality of Hopatcong A Lake?
- Hopatcong A Lake in Sussex County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 4.3 ft visibility.
Is Hopatcong A Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Hopatcong A Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pesticides, pH / acidity, pCBs, temperature. Check local advisories before you swim.
Explore Hopatcong A Lake across LakeQuality
More lakes in New Jersey
Other Lakes in New Jersey
Eutrophic Lakes in New Jersey
Where this data comes from
43 measurements from 7 monitoring stations, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Princeton Hydro LLC
PRINCETONHYDRO43 samples · 2024–2025
Monitoring station identifiers (7)
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