Montz is a census-designated place in St. Charles Parish, Louisiana, United States. It first appeared in the 2000 census with a population of 1,120. The 2020 census indicates a population of 2,106. The Bonnet Carré Crevasse occurred in and near the present-day location of Montz. It was one of several levee breaches in the Bonnet Carré area in the mid-to …Montz is a census-designated place in St. Charles Parish, Louisiana, United States. It first appeared in the 2000 census with a population of 1,120. The 2020 census indicates a population of 2,106. The Bonnet Carré Crevasse occurred in and near the present-day location of Montz. It was one of several levee breaches in the Bonnet Carré area in the mid-to-late-1800s. Bonnet Carré was approximately 50 kilometers from New Orleans, Louisiana. The breach occurred when excess water from the Mississippi River flowed over the east bank levee of Bonnet Carré.