Grand Chenier is an unincorporated community in Cameron Parish, Louisiana, United States. Its population is estimated at 352. Its ZIP c…Grand Chenier is an unincorporated community in Cameron Parish, Louisiana, United States. Its population is estimated at 352. Its ZIP code is 70643. St. Eugene Catholic Church in Grand Chenier, which is affiliated with the Roman Catholic Diocese of Lake Charles, was established in 1961 by the Most Reverend Maurice Schexnayder, then the Bishop of Lafayette.