Here is some information in the event of an emergency.  

Who is responsible to sound sirens in the event of an emergency?
Each county’s emergency management office or “Warning Point” will sound the sirens in case of an emergency at Indian Point. This is the signal for the public to tune in to their local Emergency Alert System (EAS) radio or television station. Each county government decides when to sound the sirens, and efforts are coordinated among the four counties.

What happens if a siren doesn’t work when it is sounded?
In the unlikely event that a siren does not work, each county’s emergency workers are trained and prepared to use alternate means.  This may include automated telephone callouts or route alerting by local police.

Who do I call to verify if the sirens being sounded are for a test or an emergency?
Call the Westchester County Emergency Management office at 1-800-942-1452.
Call the Rockland County Emergency Management office at 1-800-942-1450.
Call the Orange County Emergency Management office at 1-800-942-7136.
Call the Putnam County Emergency Management office at 1-800-942-1457.

What is the coverage area for a siren?
Siren locations were selected to provide sound levels exceeding 70 dB in areas where the population density exceeds 2000 people per square mile and 60 dB in other inhabited areas. The coverage area for more than 60 dB is between 6.4 and 8.2 square miles. The coverage area for more than 70 dB is between 2.5 and 3.9 square miles. These levels compare with normal conversation (60 dB) and somewhat less than a ringing telephone (80 dB).