Natural wildfires have shaped and influenced the Otay River Valley for thousands of years. In fact, there are some plant species, such as bulb plants and more, that rely on wildfires to germinate their seeds. Many chaparral and coastal sage scrub plants begin growing weeks after a wildfire. Today about 10-15% of wildfires are naturally occuring. The rest are caused by humans.
Historically, Native Americans burned areas to increase availability of wildlife, promote healthy regrowth of vegetation. and to increase populations of bulb plants. These fire management practices changed with American settlement.
With American settlement, the focus was on fire suppression. According to Philip W. Rundel and Robert Gutafson (Introduction to Plant Life of Southern California), "a century of fire suppression in chaparral has reduced fire frequency, but chaparral fires are more intense when they do occur because the mass of unburned fuels has increased.
Santa Ana Winds begin in the fall and can occur throughout the winter months. These winds carry warm dry air from the deserts to the coast, dramatically increasing temperatures and decreasing relative humidity levels. These conditions, combined with potentially strong winds, create the perfect environment for fire to initiate and spread.
We use to think wildfire season was during the Santa Ana season. Now, because of climate change, wildfire season is essentially year around.
Frequency of wildfires in the Otay River Watershed
The Otay fire started during Santa Ana wind conditions. It was first reported on October 26, 2003. It burned close to 46,000 acres. One residence and five structures were destroyed. There were no evacuations, but the fire was clearly visible from homes in Chula Vista and Otay. The fire was contained on October 28. The cause is under investigation.
The Harris Fire began on October 21, 2007 and was contained on November 5. It started in Harris Ranch Road close to Potrero. It was one of the largest in state history. It resulted in evacuation of some communities in Chula Vista. It killed eight people. Over 1200 firefighters battled this wildfire. It even burned into Mexico. It came very close to Otay Lakes. The cause of the fire is unknown.
Photo: By :en:User:Everyguy, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3679810