A flood protection bag system includes a troughlike structure having longitudinally-extending sidewalls and a bottom wall connected therebetween, along with one or more internal walls, the internal walls serving to divide the troughlike structure into a plurality of bag chambers. The longitudinally-extending sidewalls are continuous and seamless between the ends of the troughlike structure, and the bag system can be made of a plastic such as polypropylene. In one embodiment, the bag system may be implemented in conjunction with other such bag system(s). Also, in one embodiment, a frame structure is employed to support the bag chamber(s) during filling thereof with sand or other filling material, in a manner whereby tension is applied to each of the corners of the given bag chamber being filled. Further, in one embodiment, the bag chambers are covered by way of a bag top that is openable or removable relative to the bag system.