Swimming River Reservoir
Monmouth County, New Jersey557 acresView mapDirections
NJDEP publishes the water-quality measurements for Swimming River Reservoir. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- Limited data
Swimming River Reservoir in Monmouth County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 4.8 ft visibility. Phosphorus: 28.4 µg/L. Chlorophyll-a (algae): 23.4 µg/L. Surface area: 557 acres.
Swimming River Reservoir is a 557-acre productive, nutrient-rich eutrophic lake in Monmouth County, New Jersey. Compared to the 3 other monitored lakes in Monmouth County, Swimming River Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-11-09. 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. Swimming River Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), pesticides, pCBs, turbidity. Check local advisories before you swim.
Whether Swimming River Reservoir 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 Swimming River Reservoir
These are the measurements NJDEP publishes for Swimming River Reservoir, 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 4.8 ft. Phosphorus 28.4 µg/L. Chlorophyll-a 23.4 µg/L. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 28.4µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 23.4µg/L | Fair GoodFairPoor |
| 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 Swimming River Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
557 acres
No bathymetric survey has been published for Swimming River Reservoir, so its depth is not documented here.
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Fishing Swimming River Reservoir
Reservoir Info (USACE NID)
Swimming River Reservoir is a man-made reservoir impounded by the Swimming River Reservoir Dam (completed 1901), built primarily for water supply on the Robins Swamp Brook; earth-type dam, 45 ft tall and 2,400 ft long.
- Surface area
- 557 ac
- Normal storage
- 8,000 ac-ft
- Max storage
- 14,300 ac-ft
- Drainage area
- 48.5 sq mi
- Hazard class
- High
- Owner
- New Jersey-American Water Company
Source: USACE National Inventory of Dams, NID ID NJ00082 · Operator website
EPA Impairment Status
Swimming River Reservoir 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, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NJ02030104070070-01 · Official waterbody report
Nearby Lakes in Monmouth County
Frequently asked questions about Swimming River Reservoir
Where is Swimming River Reservoir?
- Swimming River Reservoir 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 Swimming River Reservoir?
- Swimming River Reservoir in Monmouth County, New Jersey has water-quality measurements published by NJDEP, shown here as reported. Water clarity: 4.8 ft visibility. Phosphorus: 28.4 µg/L. Chlorophyll-a (algae): 23.4 µg/L. Surface area: 557 acres.
Is Swimming River Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Swimming River Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), pesticides, pCBs, turbidity. Check local advisories before you swim.
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Where this data comes from
160 measurements from 4 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_BFBM160 samples · 2020–2021
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (4)
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