A follow-up inspection is conducted six months after construction has been completed, then once every two years.
Inspectors look for any movement in the dam and any kind of seepage.
Although a dam looks motionless, internal stresses develop throughout its life as it settles and shifts under the enormous weight of the water and the structure itself. To detect potentially dangerous changes, every big dam should have an array of instruments such as strain gauges and pressure measuring devices buried inside the dam. They result in a comprehensive report of all aspects of the structure with recommendations for improvement. The results of each inspection are evaluated and structural design adequacy studies performed as necessary. Where the need for corrective action is indicated to eliminate a public hazard or to protect structures, owners are advised of existing or potentially-hazardous structural conditions and furnished technical advice on recommended corrective measures.