Corrosion of reinforcing steel in the reinforced concrete structures can be a serious problem when chloride ions and/or carbonation of concrete compromise the protective oxide film formed on the steel surface in high pH environment. This is because concrete can experience structural damage when rust formation becomes significant resulting in concrete cracks and spalls. A tidal power plant was constructed in the middle of a man-made seawall that divides Sihwa Lake and Yellow Sea near In-Cheon International Airport in Korea. Due to harsh marine exposure condition with 30-feet tidal variation, the K-Water Corporation was concerned with long-term structural integrity of the massive reinforced concrete structure and developed a corrosion monitoring program in the design stage to have an ability to determine when timely maintenance actions are required. As a result, 19 sets of two types of commercially available corrosion sensors were placed at four elevations (submerged zone, tidal zone, splash zone, and atmospheric zone) in the strategically selected locations. Since the first monitoring data were collected in November 2012, five rounds of data collection have been made at every quarter. This presentation will discuss the adopted corrosion monitoring methodology and preliminary findings of the monitoring project.