Ada County residents are subjected to a wide range of weather events, including: thunderstorms, hail, lightning, high winds, tornadoes, winter storms, blizzards, extreme heat, drought, and others. These weather events cause property damage and injuries or deaths almost every year and at all times of the year.
Although fire codes and fire-resistant building materials have reduced the threat, structural fires still happen all too frequently. In 2004 fire killed more Americans than all natural disasters combined. Fire-related fatalities occur on a regular basis in Ada County.
A variety of hazardous substances are produced, stored, and used in Ada County. In addition, they are routinely transported on the roughly 2,000 miles of roads in the county. Commonly found chemicals include: anhydrous ammonia, chlorine, ethanol, formaldehyde, hydrofluoric acid, nitric acid, propane gas, sulfuric acid, and various petroleum products, such as gasoline. Chemicals are also shipped on railroads and in several pipelines that run through the county.
Hundreds of wildfires occur in Ada County in most years. Most wildfires do not get very large before they are extinguished, but there are exceptions. In 1992 a fire blackened 257,000 acres in Ada and Boise Counties, and in 1996 the Eight Street wildfire burned 15,300 acres in the Boise Foothills. In 1995 two volunteer firefighters were killed near Kuna while battling a wildfire. The growing wildland-urban interface increases the likelihood of structural damage and human casualties.
A nuclear detonation on any U.S. city, although unlikely, would cause devastation on a scale previously unknown in America. A hydrogen bomb, otherwise known as a fusion bomb, is orders of magnitude more destructive than a Hiroshima-style, fission bomb. During the cold war era Boise was identified as a possible risk area.
There are three large upstream dams on the Boise River that have a combined storage capacity of about 1,000,000 acre/feet. Sudden failure of one of these dams, if it were full, would cause widespread devastation and probably high loss of life. A high wall of water would flow down the Boise River to Brownlee Reservoir.
A terrorist incident can take many forms, including: biological, chemical, explosive, radiological, or armed attacks. No free society is immune to terrorist attacks. Like most communities, Ada County contains a number of agencies and facilities that could be potential targets for terrorists.
Idaho ranks 6th highest in the nation for earthquake risk. Two of the largest quakes in the lower 48 states in the last fifty years occurred in or near Idaho and were felt in Ada County. Most buildings constructed prior to the late 1980s were built without much regard to earthquake resistance. Even moderate earthquakes can cause widespread damage to such things as buildings, roads, bridges, and water and sewer lines.