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City of Santa Ana Emergency Operations Plan
<br />Part I Basic Plan
<br />Damaging floods caused by the Santa Ana River, known as "Great Floods," appear in records as early as 1770,
<br />when a massive flood was recorded in the notes of Father John Crespi on January 7, 1770. Major floods in Orange
<br />County on the Santa Ana River have occurred in 1810, 1815, 1825, 1884, 1891, 1916, 1927, 1938, 1969, 1983,
<br />1993 and 1997. The greatest flood in terms of water flow in the Santa Ana River was in 1862 with an estimated
<br />flow rate of 317,000 cubic feet per second (cfs). This was three times greater than the Great Flood of 1938,
<br />estimated at 110,000 cfs. An average flow on the Santa Ana River today usually amounts to a cfs in the low
<br />1,000's. The most damaging in terms of cost was the Great Flood of 1969. The County's population and
<br />development had significantly increased by then, creating greater potential for loss.
<br />Great Flood of 1862- The storm and flood of January 1862, called the Noachian deluge of California, were
<br />unusual in two ways: 1) the storm occurred during the very severe drought of 1856-1864 and 2) the flooding was
<br />extremely long, lasting 20 days. Under normal circumstances, major floods last no longer than a few days.
<br />Great Flood of 1916 — The flood on January 27, 1916 inundated a large area in Santa Ana, flooding Main Street
<br />with water 3 feet deep. The farming area, today the City of Westminster, was also flooded. A total of six bridges,
<br />three traffic bridges and three railroad bridges, washed away and four people drowned.
<br />Great Flood of 1938 — The flood of 1938 was considered the most devastating of all Orange County floods in the
<br />20' Century and affected all of Southern California. The storm began on February 27 and lasted until March 3.
<br />Anaheim, Santa Ana, and Garden Grove were hardest hit. In the Santa Ana Basin, 34 people died and 182,300
<br />acres were flooded. Two major railroad bridges, seven traffic bridges, and the small town of Atwood (now part of
<br />the City of Placentia) were destroyed. As the Santa Ana River inundated the northwestern portion of Orange
<br />County, train service to and from Santa Ana was cancelled and communication with the outside world was
<br />essentially nonexistent. Damage exceeded $50 million. The flood and its damage were a catalyst for construction
<br />of Prado Dam, developed as part of the Army Corps of Engineers flood control protection plan. Government
<br />officials estimate that today without the protection of Prado Dam, a flood of this magnitude would cause as many
<br />as 3,000 deaths and top $40 billion in damages.
<br />Great Flood of 1969 — The floods of January -February 1969 were the most destructive on record in Orange
<br />County. Previous floods had greater potential for destruction, but the County was then relatively undeveloped. A
<br />drought that began in 1945 was relieved by only two wet years until the floods in 1969. Rainfall was continuous
<br />from January 18 to January 25, resulting in widespread flooding on January 25-26. Orange County was declared
<br />a national disaster area on February 5. A second storm system from February 21 to 25 once again brought rain to
<br />the already saturated ground, culminating in a disastrous flood on February 25.
<br />The largest peak outflow from Santiago Reservoir since its inception in 1933 occurred in February. On February
<br />25, the reservoir at Villa Park Dam reached its capacity for the first time since its construction in 1963. Even
<br />though the outlet was discharging up to 4,000 cfs, spillway overflow occurred at 1:30 p.m. on February 25 and
<br />continued for 36 hours, reaching a maximum peak outflow from the dam of 6,000 cfs. The safety of the dam was
<br />never threatened. However, the outflow into Santiago Creek caused serious erosion downstream in Orange and
<br />Santa Ana and in portions of parks and golf courses. Trees and debris inundated the streambed. Houses,
<br />apartments, gardens, swimming pools, and bridges eroded away. Numerous residents and volunteers worked
<br />around the clock to remove debris, sandbag eroding embankments, cordon off danger zones, issue warnings, and
<br />make temporary repairs. U.S. Marine Corps helicopters dropped junked cars along the banks of the creek below
<br />Bristol Street in an effort to prevent further undermining of homes. A Southern Pacific Railroad bridge, water and
<br />sewer lines, a pedestrian overcrossing, and three roads washed out. Approximately 2,000 Orange and Santa Ana
<br />residents were evacuated from houses bordering Santiago Creek.
<br />Great Flood of 1983 — The presence of El Nino spawned the flood of 1983. The intense downpour concentrated
<br />in a local area and resulted in the highest waves to crest onshore in 10 years. Meanwhile, the Santa Ana River
<br />crested at the mouth of the ocean, creating a disaster for the low-lying areas of Huntington Beach with floodwaters
<br />three to five feet deep. In addition, the pounding surf destroyed a section of the Huntington Beach Pier, resulting
<br />in a complete renovation of the pier.
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