Public Alert and Notification

Early Warning System Sirens

The San Luis Obispo County Early Warning System (EWS) sirens extend throughout the Emergency Planning Zone. Although the siren system was installed primarily for an emergency at Diablo Canyon Power Plant, they can be utilized for any emergency where protective actions are necessary by the general public such as an evacuation due to a tsunami or dam failure. When activated, the sirens will produce a steady wail for 3-5 minutes. The siren system is an indication that the Emergency Alert System has been activated and emergency information will be provided on local radio and TV stations. The EWS sirens are tested regularly, including twice monthly silent tests, quarterly growl tests, and a full scale annual test in late August.  No action is required on the part of the public during these tests.

Emergency Alert System

The Emergency Alert System (EAS) is a national public warning system that requires radio and TV stations to broadcast emergency information provided by local, state and federal officials. During an emergency, local officials could activate the EAS to provide emergency information and actions necessary to the general public over local radio and TV stations.  Local radio and TV stations are an effective way to stay tuned to emergency information. It is essential to have battery-powered devices, such as a battery operated radio to stay tuned during power outages. The Emergency Alert System is tested on the first Thursday of every month. 

Wireless Emergency Alerts

Wireless Emergency Alerts (WEA) are emergency alert messages similar to text messages that are sent to WEA-enabled cell phones in the vicinity of an emergency that requires the public to take action. The alerts include a unique sound and vibration but are limited to 90 characters.   

WEA messages are sent by authorized emergency officials for local emergencies but can also be used by the President in times of national crisis. 

Registration is not required to receive WEA, but those interested in receiving alerts should verify their cell phone settings are set to receive messages.  

Learn more about WEA.


Reverse 9-1-1

San Luis Obispo County officials have the capability to inform the public of an emergency by utilizing an emergency telephone notification system, known as Reverse 911. This system allows emergency officials the ability to notify residents and businesses in a designated area of an emergency and actions they may need to take.  This system utilizes the 9-1-1 telephone database and therefore is able to contact listed and unlisted land-line telephones.  If you have a Voice over IP (VoIP) or cellular telephone that you would like to be notified on, you must self-register those telephone numbers. Register your number with the Sheriff's Office today.  

Learn more about Reverse 911.

NOAA Weather Radio

Emergency alert radio signals are provided by the National Oceanographic and Atmospheric Administration's (NOAA) National Weather Service (NWS). These radio signals are not accessible over AM/FM radios but are received by NOAA weather radios.  Weather alert radios can be used to alert the public of other serious emergencies, not just weather events.

NOAA Weather Radios are typically available at electronic stores and online.

Visit their website to learn more about these inexpensive radios at the NWS notification system.

Social Media

In addition to the traditional forms or public notification, social media is an additional method that will be utilized to share information regarding the emergency.  Although emergency officials will continue to utilize alert and notification systems, we encourage the public to connect with us on Facebook and Twitter to stay abreast of emergencies throughout the county. 

Route Alerting

Route Alerting is a form of alert and notification that is used frequently in small scale emergencies or during rapidly changing situations in a designated area.  In route alerting, emergency officials drive or walk through an affected or potentially affected area alerting residents in that area of the emergency and actions they need to take. Route Alerting can be conducted door to door or via a public address system on a police car, fire engine etc. Although route alerting is effective when other systems are unavailable, it is dependent on resource availability and can be a slow process. Route Alerting is traditionally utilized only in areas that are ordered to take action.