A closure dam was constructed on Little Feni River at Musapur Union, Noakhali District by Bangladesh Water Development Board (BWDB) in 2016. The study assessed crop production fluctuations between pre and post period of the construction of this dam. Data were collected from Department of Agricultural Extension (DAE), Companiganj Upazila, and BWDB, Noakhali. Besides, an inception meeting was arranged at DAE with different participants for two consecutive days and three focused group discussions (FGD) from almost all stakeholders were done to triangulate the result. The trend was calculated by the data retrieved from 2011 to 2018 for the projection of the study. The result showed a revolutionary increasing trend for Brassica juncea, Arachis hypogaea, and Allium sativum with 1214%, 1400%, and 1600%, respectively. Followed by, the positive trend was showed for Oryza sativa, Cajanus cajan, Pisum sativum, Capsicum annuum, wintry vegetables and Cucumis sativus with 30.97%, 116.41%, 200%, 145.83%, 52%, 475%, respectively. And nearly stable trend was found for Ipomoea batatas, spices and Lathyrus sativus with a positive trend of 4%, negative trend of 7.59% and 8.86%, respectively. The study concluded that construction of closure dam might be greatly influenced in the high production rate of crops in the study area.