Geismar is an unincorporated area in Ascension Parish, Louisiana. Geismar is south of Prairieville and north of Gonzales. The community has two schools, Dutchtown Primary/ Middle School and Dutchtown High School, which are ranked among the top schools in the state of Louisiana. The Mississippi River runs through the town. The area is vulnerable to hurricanes and tropical systems due to its low elevation and its proximity to the coast of southeast Louisiana.
On the morning of June 13, 2013, an explosion occurred at the Williams Olefins plant in Geismar. The plant produces 1.3 billion pounds of ethylene and 90 million pounds of polymer grade propylene annually. Over 70 people were injured in the explosion, and at least two people have died.