Marrero Plant Wastewater Treatment Facility, Marrero, Louisiana

Marrero Plant is a major wastewater treatment facility located in Marrero, Jefferson Parish, Louisiana, serving a population of approximately 173,100. Situated in the Greater New Orleans metropolitan area, the plant plays a critical role in managing municipal wastewater for this suburban community on the west bank of the Mississippi River. As a large agglomeration serving over 150,000 people, the plant is subject to stringent federal and state regulations under the US Clean Water Act. The National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Louisiana Department of Environmental Quality, governs its discharge limits and monitoring requirements. Facilities of this scale typically employ secondary or advanced treatment to meet permit conditions. The plant's treated effluent ultimately enters the Mississippi River, which flows into the Gulf of Mexico. This discharge contributes to the nutrient load in the river, which is a key factor in the seasonal hypoxic zone in the Gulf. The plant's performance is therefore important for downstream water quality and marine ecosystem health.

The plant discharges into the Mississippi River, which drains a vast watershed spanning 31 US states and two Canadian provinces before emptying into the Gulf of Mexico. The lower Mississippi River and its delta support diverse aquatic life, including commercially important fish and shellfish species. Nutrient enrichment from wastewater and agricultural runoff contributes to seasonal hypoxia in the Gulf, making nutrient removal an important consideration for plants in this basin.