ABSTRACT

The Norco Aquifer is the shallowest, regionally continuous aquifer in the Geismar, Louisiana area. The aquifer is an important source of drinking water in the area. The aquifer is also used for process water supply by many of the plants in the area.

The Norco Aquifer has not been publicly studied since the mid-1960's in the Geismar area. Past geophysical well logging combined with recent geophysical logging, well installations, pumping tests, and three-dimensional geologic modeling has resulted in an updated understanding of the geologic and hydrogeologic setting of the Norco Aquifer in the Geismar area. The top and bottom elevations, and the net thickness of the aquifer have been defined from the many wells and test holes that have been completed since the 1960's. Recent pumping tests, with nearby monitoring wells, have provided a detailed understanding of the hydrogeologic properties of the aquifer.

The understanding of the relationship between the Mississippi River and the Norco Aquifer in the Geismar area has changed with the collection of recent data. The groundwater within the aquifer was previously thought to flow both away from and toward the Mississippi River, based on the stage of the river. Recent water level elevation and river stage data have shown that groundwater flow in the Geismar area is always away from the river and the flow direction is fairly constant.

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