City of Irvine
2020 Local Hazard Mitigation Plan
• Heavy rains in January 1916 caused 22 deaths, widespread flooding, and the destruction of several boats moored at Newport Beach. • The most extensive flooding in Southern California history occurred in late January 1916, when 8 to 58 inches of rainfall were recorded in various measuring stations across the region. Numerous dams breached, resulting in property damage and loss of life. Four people died in Orange County. • In 1922, heavy rains flooded various rights-of-way across the region, and the Santa Ana River exceeded its normal surface elevation by three feet. • Heavy rains on New Year’s Eve and Day of 1934 impacted cities across Southern California. In total, 45 people lost their lives, and some canyons became inundated with floodwaters 10 feet high. • A 1937 rainstorm in February deposited 4.25 inches of rain in nearby Long Beach. A few people were killed in the ensuing flooding, and some dams failed across the region. • In 1938, the deadliest flooding event in Southern California history was caused by a tropical storm. Up to 30 inches of rain fell in the mountain areas, including 22 inches at the point of origin for the Santa Ana River watershed. In Orange County, 45 died, including 43 in Atwood (now part of present-day Placentia). • In 1939, a tropical storm brought heavy rain to all Southern California, resulting in 45 deaths on land and 48 more deaths at sea. • In November 1963, heavy rains fell on Southern California. More than three inches were recorded in coastal Orange County locations. The flooding injured 6 people. • A December 1964 rainstorm caused flooding that killed 40 people across Los Angeles and Orange Counties. • Heavy storms in November 1965 dropped between 16 and 20 inches of rain in the mountains of Southern California, causing regional flooding and 15 deaths. • In January and February, 1969 rain fell almost continuously from January 18 to January 25, resulting in widespread flooding. Orange County was declared a national disaster area on February 5. A second storm hit on February 21 and lasted until February 25, bringing rain to the already saturated ground. This second storm culminated in a disastrous flood on February 25. The storm resulted in the largest peak outflow from Santiago Reservoir since its inception in 1933. The reservoir at Villa Park Dam reached its capacity for the first time since its construction in 1963; the dam had a maximum inflow of 11,000 cubic feet. The outlet conduit was releasing up to 4,000 cubic feet, yet the spillway overflowed at 1:30 p.m. and continued for 36 hours. The maximum peak outflow from the dam reached 6,000 cubic feet. Although the safety of the dam was never threatened, the outflow caused serious erosion downstream in the cities of Orange and Santa Ana and in some parks and golf courses. A Southern Pacific Railroad bridge, water and sewer lines, a pedestrian overcrossing, and three roads washed out. Approximately 2,000 Orange and Santa Ana residents were evacuated from houses bordering Santiago Creek. In January 1995, flooding inundated the region, causing an estimated $55 million in property damage and prompting a federal disaster declaration. • In February 1998, all Southern California was impacted by heavy rains when 2 to 5 inches fell across the region. Many roads and bridges were washed away or destroyed, and widespread power outages occurred. Property damage reached $100 million worth, and two people lost their lives. Irvine was directly impacted by many of these issues during this event.
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