Carnegie Lake
Carnegie Lake in Mercer County, New Jersey has a water quality grade of F (Algae-prone). Water clarity: 2.1 ft visibility. Phosphorus: 110.5 µg/L. Chlorophyll-a (algae): 40.8 µg/L. Surface area: 245 acres.
- Clarity
- 2.1 ft
- Area
- 245 acres
- Type
- Hypereutrophic
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Carnegie Lake →
Carnegie Lake is a 245-acre highly nutrient-loaded hypereutrophic lake in Mercer County, New Jersey. Water quality is graded F based on 2 sampling years through 2023. Compared to the 14 other monitored lakes in Mercer County, Carnegie Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-09-26. 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 2.1 ft of visibility. Phosphorus level: 110.5 µg/L. Chlorophyll-a: 40.8 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.1 ft | Not graded |
| Phosphorus | 110.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 40.8 µg/L | Poor |
| Trophic State Index (TSI) | 69 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Carnegie Lake
Compare lakeside cabins, hotels, and vacation rentals near Carnegie Lake in Mercer 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 Carnegie Lake are listed below.
Top-rated places to stay near Carnegie Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 245 acres |
No bathymetric survey has been published for Carnegie Lake, so its depth is not documented here.
Fishing Carnegie Lake
Reservoir Info (USACE NID)
Carnegie Lake is a man-made reservoir impounded by the Carnegie Lake Dam (completed 1900), built primarily for recreation on the Millstone River; concrete-type dam, 28 ft tall and 724 ft long.
- Surface area
- 245 ac
- Normal storage
- 1,344 ac-ft
- Max storage
- 5,326 ac-ft
- Drainage area
- 159.1 sq mi
- Hazard class
- Significant
- Owner
- Princeton University
Source: USACE National Inventory of Dams, NID ID NJ00150 · Operator website
EPA Impairment Status
Carnegie 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 NJ02030105110020-01 · Official waterbody report · Matched by proximity (1.27 km)
County Ranking
Ranked #3 of 15 lakes in Mercer County
Nearby Lakes in Mercer County
Frequently asked questions about Carnegie Lake
Where is Carnegie Lake?
- Carnegie Lake is a lake in Mercer 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 Carnegie Lake?
- Carnegie Lake in Mercer County, New Jersey has a water quality grade of F (Algae-prone). Water clarity: 2.1 ft visibility. Phosphorus: 110.5 µg/L. Chlorophyll-a (algae): 40.8 µg/L. Surface area: 245 acres.
Is Carnegie 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. Carnegie Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 40.8 µg/L. Always check local health department advisories before swimming.
Explore Carnegie 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
116 measurements from 4 monitoring stations, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- NJDEP Bureau of Freshwater and Biological Monitoring
NJDEP_BFBM116 samples · 2022–2023
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (4)
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