Lessons learned from the Saint Francis Dam Disaster help to prepare Ventura County Public Works Agency in the event of more flooding
New online resource allows Ventura County to combat unpredictable weather conditions.
VENTURA — Oct 11th, 2023 – Known as one of the greatest disasters in California history, the St. Francis Dam collapsed just before midnight on March 12, 1928. Twelve billion gallons of water and debris roared down the Santa Clara River Valley from San Francisquito Canyon to the Pacific Ocean, 54 miles away. During the five and a half hours the water took to reach the ocean, more than 530 people were swept away.
Geneva Montes (aged 102), one of the remaining survivors of the 1928 St. Francis Dam Disaster, recalls climbing onto mattresses with her family and riding on top of the raging floodwaters for at least 15 to 20 minutes, traveling over two miles downstream. Geneva remembers the sounds vividly, “You could hear the noise of water like thunder.”
Almost 100 years later, Ventura County (VC) is still no stranger to flooding. Ventura County was declared a federal flood disaster area following the winter storms in late 2022 and early 2023. Since then, Southern California experienced the anomaly of being caught in the path of a tropical storm and unusual summer rain; it is probable that Ventura County may face another bout of heavy rain and flooding this coming winter. To prepare residents, the Ventura County Public Works Agency (VCPWA) just launched https://vcfloodinfo.org/ .
This website has many helpful resources to inform, educate, and prepare both local and non-local residents affected by flooding. Real-time storm data is linked from this to the VC Flood Warning System, allowing residents and first responders, such as Ventura County’s Fire Department, to know the status of flooding in specific areas; this includes detailed instructions on how to set up the flood warning system on mobile devices, flood zone hazard-mapping, and the latest weather news. Additionally, sandbag information, flood insurance, FEMA floodplain mapping, elevation certificates, property protection suggestions, and more are available in multiple languages.
The website features the Ventura County Flooding History page, with a story map that includes flooding as far back as 1907 and as recent as the 2023 storms. This past information allows the county to look at former flooding impacts and plan for a better future, considering the infrastructure systems that worked or failed, and how Ventura County communicated with residents.
One of these early historical flood events was the St. Francis Dam failure. The exact cause of the dam’s failure was not definitively determined, but it is believed to have been due to a combination of factors, including design flaws, construction defects, and geological instability at the site. The incident served as a wake-up call for the engineering community, leading to advancements in dam design and safety protocols to prevent similar disasters in the future.
Ventura County’s biggest water holding dams include Lake Piru, Bard Lake, and Lake Casitas, which collectively hold 310,000 acre-feet (about half the area of Yosemite National Park) at capacity.
The most significant dam the County of Ventura owns is the 168-ft-tall Matilija Dam in the Ventura River watershed on Matilija Creek north of Ojai. There has been extensive support for the dam’s removal. Constructed in 1948, the dam’s main purpose was to create a water supply reservoir. However, over several decades, the reservoir became filled with sediment and is no longer needed as Lake Casitas provides that needed water supply. Out of the original capacity of 7,000 acre-feet, only approximately 100-acre feet capacity remains behind Matilija Dam.
The Matilija Dam Ecosystem Restoration Project is immense in terms of planning, cost, and size. It has been estimated it will cost $230 million to modernize downstream infrastructure. This includes flood protection, water supply reliability, community climate resilience, renewing access to prime spawning and rearing habitat in the Matilija Creek headwaters for the federally endangered southern California steelhead, and restoring natural sediment transport and ecosystem function to enhance floodplain, riparian, and near-shore coastal habitats. VCPWA has been working on this initiative since 1999 and in 2022, completed a new Santa Ana Bridge in Oak View as part of modernized infrastructure needed before dam removal.