History of Hazards in Boulder County
Last Updated on Wednesday, 31 July 2013 18:11
In Boulder County we are familiar with the multi-hazards of fire and flood. But we are at risk from other hazards, too. Winter storms, lightning, tornados, and even earthquakes have the potential of causing damage to property and injury to people in our communities.
Boulder County’s Multi-Hazard Mitigation Plan identifies the types of hazards that threaten our communities, evaluates the risks from those hazards, and outlines a strategy to reduce or eliminate that risk. The plan covers 18 different hazards from avalanches to windstorms.
The Multi-Hazard Mitigation Planning Committee is currently updating and revising the plan which was last adopted in 2016. As part of the process to evaluate the risks posed by different hazards the committee will review past occurrences in our communities.
Here is a short history of some of the hazards the plan addresses.
Lightning: Colorado ranks second in the U.S. for the number of lightning fatalities (Florida is first). In the past 30 years, 29 people have been injured by lightning in Boulder County. 4 people have been killed by lightning during that same period.
Hailstorms: Our summer thunderstorms in Boulder County often bring hail. Hailstorms can be very destructive. In 2018, Colorado ranked #1 in the U.S. in hail damage and in 2017 experienced the second most damaging hailstorm in U.S. history, triggering $2.3 billion in damage. On average, 130 hailstorms occur in Colorado each year.
Pandemic Flu: In 1918 hundreds of Coloradans lost their lives to the Spanish Flu outbreak. More than 20 million people died worldwide. Pandemic flu continues to pose a significant threat. As recently as 2010 a new strain of swine flu killed 17,000 worldwide. According to the Colorado Department of Public Health and the Environment, a severe flu pandemic could affect 30% of our state’s population causing the shutdown of critical services and facilities.
Winter Storms: Severe winter weather is a common hazard in Boulder County. In December of 2006 a severe winter storm dropped 19 inches of snow on Boulder forcing the closure of schools, businesses, roads, and airports, and stranding thousands of holiday travelers. The President declared a snow emergency making Boulder County eligible for more than $275,000 in snow removal costs. Winter storms can bring added hazards in spring when snowmelt can lead to flooding.
Wildfire: Many fire suppression policies of the last century have increased vegetation densities to as much as 100 times their natural state. This increased fuel load coupled with drought, high temperatures, high winds, and an increased human presence results in an environment especially prone to the danger of wildfire. Boulder County’s most destructive wildfire in terms of property loss occurred in 2010 when the Fourmile Fire destroyed 169 homes.
Flood: One of the most destructive floods in the history of our county occurred in 1894. Snowmelt combined with heavy rain caused a flood that destroyed every bridge in Boulder Canyon and covered much of the floodplain in up to 8 feet of water. Boulder County again experienced historical flooding in 2013 when over 18” of rain fell in a matter of days. Although floods can happen at any time, the period of greatest flood risk in Boulder County is from April to September. Wildfires increase the danger of flood by reducing ground cover and altering the soil’s capacity to absorb water. Other changes to the landscape can also increase flood hazards.
Windstorms: According to the National Oceanic and Atmospheric Administration, Boulder County experiences some of the strongest winds in the country. Gusts have been measured as high as 147 miles per hour. In January 1982, a windstorm with gusts comparable to a category 3 hurricane caused minor damage to 40% of all buildings in the City of Boulder, erosion damage to 50,000 acres of farmland, and in total resulted in more than $17 million in damages across the County. Chinook Winds blow from the west, over the Continental Divide, and into the foothills. These winds are generally warm and dry and can contribute to wildfire hazards.