Raising the alarm
Should a danger arise from a dam rupturing or overflowing, the NEOC is informed directly, either by the plant owner or by the operations centre of the affected cantonal police station. From this moment on, the relevant agencies stay permanently in contact. The NEOC acts as an information platform and is in charge of providing the Dam Safety Section at the Swiss Federal Office of Energy SFOE with initial information.
In relation to large dams, the area is divided into two zones when it comes to raising the alarm: the vicinity zone, which as a general rule, covers the area that would be flooded within a maximum of two hours following a sudden dam burst. Beyond this area is the remote zone. The vicinity zone is equipped with special water alert sirens (low continuous tone). In the remote zone, the general alert is raised (ascending and descending tone). This is to inform the population that they should listen to the radio for further information and instructions. The water alert is always sounded after the general alert. This is a signal to the population that they must leave the endangered area immediately. If the water alert sounds before the general one, it is a false alarm.
The NEOC is responsible for sounding the general alert and ensures the transmission of instructions over radio, through its special channels.
The cantons are responsible for protective measures. Leaflets on what to do in such situations can be obtained in every municipality.