On December 22, 2008, a retention pond dam in Roane County, Tennessee, broke, spilling over a billion gallons of coal fly ash slurry into the Emory River and the surrounding countryside. The Emory River flows into the Tennessee River, which supplies water to millions of people.
When a disaster occurs, such as the one in Roane County, many people need to know about it. In the past, the news of such an event would go out over radio and television broadcasts. However, that process takes time, and many people might not be watching television or listening to the radio. An increasingly large segment of the population listens to music on smartphones rather than the radio, watches entertainment programs on tablet computers instead of on television, and relies on mobile phones instead of landlines. Sending alerts to wireless mobile devices is faster and provides a way to contact those who would otherwise miss the alert