L Pontchartrain Lake
St. Tammany Parish County, LouisianaView mapDirections
LDEQ publishes the water-quality measurements for L Pontchartrain Lake. Here is what has been measured.
- Limited data
L Pontchartrain Lake in St. Tammany Parish County, Louisiana has water-quality measurements published by LDEQ, shown here as reported. Water clarity: 3.6 ft visibility.
L Pontchartrain Lake is a lake in St. Tammany Parish County, Louisiana.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2021-12-07. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether L Pontchartrain Lake 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 L Pontchartrain Lake
These are the measurements LDEQ publishes for L Pontchartrain 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 3.6 ft. TSI 59.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.6ft | 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. | 59 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
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Frequently asked questions about L Pontchartrain Lake
Where is L Pontchartrain Lake?
- L Pontchartrain Lake 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 L Pontchartrain Lake?
- L Pontchartrain Lake in St. Tammany Parish County, Louisiana has water-quality measurements published by LDEQ, shown here as reported. Water clarity: 3.6 ft visibility.
Is L Pontchartrain Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore L Pontchartrain Lake across LakeQuality
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Where this data comes from
11 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-LA11 samples · 2020–2021
Analytical methods
- Secchi disk 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.