Lake Pontchartrain
St. Tammany Parish County, LouisianaView mapDirections
LDEQ publishes the water-quality measurements for Lake Pontchartrain. Here is what has been measured.
- Eutrophic
- Limited data
Lake Pontchartrain in St. Tammany Parish County, Louisiana has water-quality measurements published by LDEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 75.5 µg/L. Chlorophyll-a (algae): 9.5 µg/L.
Lake Pontchartrain is a productive, nutrient-rich eutrophic lake in St. Tammany Parish County, Louisiana. Compared to the 2 other monitored lakes in St. Tammany Parish County, Lake Pontchartrain ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-12-07. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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. Check local advisories before you swim.
Whether Lake Pontchartrain is safe to swim in today is a call for the Louisiana Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Pontchartrain
These are the measurements LDEQ publishes for Lake Pontchartrain, 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 3.3 ft of visibility. Phosphorus 75.5 µg/L. Chlorophyll-a 9.5 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 75.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 9.5µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Pontchartrain
Answers come straight from the public measurements and survey records on this page.
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Fishing Lake Pontchartrain
Nearby Lakes in St. Tammany Parish County
Frequently asked questions about Lake Pontchartrain
Where is Lake Pontchartrain?
- Lake Pontchartrain is a lake in St. Tammany Parish County, Louisiana. Its water-quality measurements are published by LDEQ and shown on this page as reported.
What is the water quality of Lake Pontchartrain?
- Lake Pontchartrain in St. Tammany Parish County, Louisiana has water-quality measurements published by LDEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 75.5 µg/L. Chlorophyll-a (algae): 9.5 µg/L.
Is Lake Pontchartrain safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
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Eutrophic Lakes in Louisiana
Where this data comes from
49 measurements from 1 monitoring station, 2020–2021. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- USGS Louisiana Water Science Center
USGS-LA49 samples · 2020–2021
Analytical methods
- Secchi disk method
- P, wu, WCA, persulfate CF color
- Plant pigments, sonication & 445
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.