Smithville Mid-Lake
Burlington County, New Jersey37 acresView mapDirections
NJDEP publishes the water-quality measurements for Smithville Mid-Lake. Here is what has been measured.
- Impaired · Metals (other than mercury)
- Limited data
Smithville Mid-Lake in Burlington County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 90 µg/L. Surface area: 37 acres.
Smithville Mid-Lake is a 37-acre lake in Burlington County, New Jersey.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-06-17. Methodology: how these readings are compared.
Swimming conditions
No readingBacteria advisory
Nutrient and algae readings are not a swimming clearance. Smithville Mid-Lake is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), turbidity. Check local advisories before you swim.
Whether Smithville Mid-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 Smithville Mid-Lake
These are the measurements NJDEP publishes for Smithville Mid-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 0.7 ft of visibility. Phosphorus 90 µg/L. TSI 76.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 0.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 90µg/L | Measured, not scored 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. | 76 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Smithville Mid-Lake
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Lake Details
Surface area
37 acres
No bathymetric survey has been published for Smithville Mid-Lake, so its depth is not documented here.
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Fishing Smithville Mid-Lake
Reservoir Info (USACE NID)
Smithville Mid-Lake is a man-made reservoir impounded by the Smithville Dam (completed 1935), built primarily for recreation on the North Branch Rancocas Creek; timber crib-type dam, 10 ft tall and 60 ft long.
- Surface area
- 37 ac
- Normal storage
- 65 ac-ft
- Max storage
- 244 ac-ft
- Drainage area
- 132 sq mi
- Hazard class
- High
- Owner
- County of Burlington
Source: USACE National Inventory of Dams, NID ID NJ00043 · Operator website · Matched by proximity (0.21 km)
EPA Impairment Status
Smithville Mid-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: Drinking water, Aquatic life, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NJ02040202040040-01 · Official waterbody report
Nearby Lakes in Burlington County
Frequently asked questions about Smithville Mid-Lake
Where is Smithville Mid-Lake?
- Smithville Mid-Lake is a lake in Burlington County, New Jersey. Its water-quality measurements are published by NJDEP and shown on this page as reported.
What is the water quality of Smithville Mid-Lake?
- Smithville Mid-Lake in Burlington County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 90 µg/L. Surface area: 37 acres.
Is Smithville Mid-Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Smithville Mid-Lake is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), turbidity. Check local advisories before you swim.
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Where this data comes from
2 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Princeton Hydro LLC
PRINCETONHYDRO2 samples · 2024–2025
Analytical methods
- 4500 P B ~ Phosphorus, sample preparation method
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