Ammonia Leak Prompts Evacuations in Mason City Before All-Clear Issued

MASON CITY, Iowa — An ammonia leak in southeast Mason City prompted a large-scale evacuation before officials gave the all-clear for residents to return home.

The incident began just before 6:30 p.m. near 633 15th St. SE at Crystal Distribution, where an emergency alert initially called for evacuations within a two-block radius.

As crews worked to locate and stop the leak, the evacuation area expanded multiple times, eventually stretching from 12th Street SE to 19th Street SE between South Penn Avenue and South Virginia Avenue. At one point, residents within three blocks of the 600 block of 15th Street SE were told to leave, and the public was asked to stay off nearby bike trails.

Officials said firefighters had difficulty locating and containing the source of the leak, and there was no estimate for when it would be safe to return.

The Mason City Fire Department has since mitigated the situation and lifted the evacuation order, allowing residents to go back home.

Cerro Gordo County Emergency Management Coordinator Eric Whipple advises anyone who notices lingering odors to open windows and use fans to ventilate their homes.

Residents with questions can contact the Mason City Fire Department or the Cerro Gordo County Communications Center.