Lake Pontchartrain
Lake Pontchartrain in St. Tammany Parish County, Louisiana has a water quality grade of C (Fair). Water clarity: 3.3 ft visibility. Phosphorus: 75.5 µg/L. Chlorophyll-a (algae): 9.5 µg/L.
- Clarity
- 3.3 ft
- Type
- Eutrophic
Lake Pontchartrain is a productive, nutrient-rich eutrophic lake in St. Tammany Parish County, Louisiana. Water quality is graded C based on 2 sampling years through 2021. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 3.3 ft of visibility. Phosphorus level: 75.5 µg/L. Chlorophyll-a: 9.5 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.3 ft | Not graded |
| Phosphorus | 75.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 9.5 µg/L | Good |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Pontchartrain
Compare lakeside cabins, hotels, and vacation rentals near Lake Pontchartrain in St. Tammany Parish County, Louisiana — 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.
Top-rated places to stay near Lake Pontchartrain
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Fishing Lake Pontchartrain
County Ranking
Ranked #1 of 3 lakes in St. Tammany Parish County
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. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Pontchartrain?
- Lake Pontchartrain in St. Tammany Parish County, Louisiana has a water quality grade of C (Fair). 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?
- Generally safe for swimming, moderate water quality. Lake Pontchartrain has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 9.5 µg/L. Always check local health department advisories before swimming.
Explore Lake Pontchartrain across LakeGrade
More Louisiana Lake Rankings
Other Grade C Lakes in Louisiana
Livingston Parish County · Fair
Livingston Parish County · Fair
Livingston Parish County · Fair
Livingston Parish County · Fair
Livingston Parish County · Fair
Livingston Parish County · Fair
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)
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.