210 ILCS 125/3.19

"Major alteration" means any change to a swimming facility or its aquatic features or appurtenances that alters the facility's functionality or as-built or as-permitted condition. This includes, but is not limited to, an alteration of a pool that changes the water surface area, depth, or volume, addition of a permanently installed appurtenance such as a diving board, slide, or starting platform, modification of the design of the recirculation system, and replacement or modification of a bather preparation facility. It does not include maintenance or minor repair or the replacement of equipment with comparable components.