Earthquakes, wildfires and floods are the natural disasters that pose the biggest threat to San Luis Obispo County.
That’s the conclusion of a local hazard mitigation plan recently updated by county emergency planners. The county Planning Commission will hold a workshop on the plan when it meets Aug. 22.
It is the latest iteration of the plan that was first developed in 2005 as required by the Federal Emergency Management Administration. “In order to remain eligible for the various mitigation grants, the LHMP must be updated and approved by FEMA every five years,” said Ron Alsop, county emergency services manager.
In a seismically active area, earthquakes easily topped the list of potential dangers. Storms and coastal erosion, tsunamis, droughts, diseases, agricultural pests and landslides are also potential threats.
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A major quake could cause hundreds of millions of dollars in damage and multiple deaths. The county’s two most recent significant temblors were the San Simeon Earthquake in December 2003, which killed two women in Paso Robles, and the Parkfield Earthquake in September 2004.
“While it is impossible to accurately predict the next earthquake event, the probability for future damaging earthquakes in San Luis Obispo County is rated as medium to high,” the report concluded.
Although a major wildfire has not occurred in the county for more than 15 years, the county’s topography and climate make it highly susceptible to fire. Summers are long and dry, and much of the county is covered with chaparral, which is highly flammable.
The county’s largest fires were the Las Pilitas, Chispa, Highway 41, Highway 58 and the Logan. Combined, these large, damaging fires consumed approximately 300,000 acres, destroyed scores of homes and cost millions of dollars to suppress.
Most recently, the Logan Fire occurred in 1997. It burned 50,000 acres and cost $6 million to extinguish. No structures were lost in the Logan Fire.
San Luis Obispo County has a history of flooding during particularly wet winters. The flooding potential is greatest along the Salinas River, San Luis Obispo Creek, Santa Rosa Creek, Arroyo Grande Creek, Morro Creek and Huerhuero Creek.
One of the most severe floods occurred during January and February of 1969. A series of storms delivered from 12 to 21 inches of rain over eight days in January, and another storm dropped five inches of rain in February.
The most severe damage to urban property occurred in San Luis Obispo, where the San Luis Obispo Creek channel filled with debris and flow over-topped the channel banks and ran onto the city streets.
The plan outlines a series of goals and actions the county is taking to minimize the risk from these hazards. Examples of these include establishing and maintaining firebreaks, retrofitting roads and levees to earthquake standards, and conducting ongoing emergency training and coordination.