The U.S. Army Corps of Engineers USACE operates and maintains 236 lock chambers at 191 lock sites on 41 waterways throughout the contiguous United States. Waterway navigational locks are important parts of the nations infrastructure. Locks enable the flow of billions of dollars of commerce and support efforts for flood control. Proper maintenance of the locks and early detection of damage is crucial however, due to shrinking budgets, adequate funding to apply traditional scheduled maintenance and visual inspection is not available. Structural health monitoring SHM systems have been considered to assist in establishing more efficient maintenance, re-pair, and replacement priorities for navigational locks. This work was undertaken to develop and implement a real-time methodology that provides lock operators with a robust, accurate warning system of gaps at the gate-to-wall interface. This initial effort, which focused on horizontally framed miter gates and on damage that is assumed to take the form of a gap at the gatewall interface quoin, developed a methodology to identify the occurrence of damage in miter gate structures using data from strain and water level gages that is collected continuously from the SHM system deployed by USACE.