Hazards by Frequency & Magnitude

1. Wildfires. 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.
2. Structural Fires. 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 in on a regular basis Ada County.
3. Hazardous Materials. A variety of hazardous substances are produced, stored, and used in Ada County. In addition, they are routinely transported on the roughly 2000 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.
4. Flooding. Small floods occur almost every year. Existing channels are inadequate to accommodate sudden large flows in many areas of dense development. Continued development along floodways has increased the frequency of damaging floods. Due to the possibility of flash floods, the most dangerous streams in Ada County are: Stuart, Crane, and Hulls Gulches and Cottonwood Creek. The possibility of injury and death from flash flooding is heightened because they are so rare that people don't recognize or accept the potential danger.

1. Nuclear Attack. 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.
2. Dam Failure. 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.
3. Terrorism. 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.
4. Earthquake. Idaho ranks 5th highest in the nation for earthquake risk. Two of the largest quakes in the lower 48 states in the last forty 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 and bridges, and water and sewer lines.