With heavy rain shattering records this week in Sacramento, leading several streams to surpass or approach flood levels, the region finds itself amid one of the wettest months in recent memory.
But forecasters are saying, at least in Sacramento, that localized flood risk from the current storm system should subside by the end of the week. And sporadic flooding observed so far this week – such as that in Rio Linda, along creek bypasses that blocked stretches of roadways – pales in comparison to what the area has seen in previous decades, or even as far back as the Gold Rush era.
The history of Sacramento flooding can be found in county government documents detailing why Sacramento, located along the confluence of the Sacramento and American rivers represents the greatest risk of any major U.S. metropolitan area. They are also well-documented by The Sacramento Bee and other publications.
Twelve of the Federal Emergency Management Agency’s 17 declarations of emergency and eight of California Office of Emergency Services’ 11 declarations for Sacramento County have been due to flooding.
The science and the geography behind our risk of flooding is relatively straightforward, as spelled out in the introduction to a 2011 update to Sacramento County’s FEMA-approved Local Hazard Mitigation Plan.
“Much of Sacramento County is low and flat. Some areas of the county are so flat that they have essentially no slope at all,” the document reads. “Natural drainageways in these areas are usually poorly defined, and drainage of storm waters is slow. ... (T)orrential rain and heavy snow frequently fall on the Western Sierra Slopes, the Southern Cascades, and to a lesser extent, the Coastal Range. As a result, flood conditions occasionally occur along the Sacramento River and its tributaries.”
National Climatic Data Center records between 1993 and 2015 show Sacramento County experienced 29 floods and four flash floods, which caused more than $13 million in property damage and ruined nearly $8 million worth of crops.
Here are five of the worst flood periods in the region’s history.
Pineapple Express hits Northern California, 1986
In February 1986, a Pineapple Express system ravaged Northern California, doing $400 million in damage, killing 13 people and evacuating 50,000 more across the state, as Sacramento County says on its flooding webpage.
Sacramento received 10 inches of rain over an 11-day span, according to the 2011 hazard mitigation documents. Reports were received of 15,000 flooded acres in south Sacramento County near Interstate 5, a stretch of which was closed for four weeks with 3 feet of standing water, as residents noted.
“Substantial damages” to homes and businesses were also reported, but no deaths or injuries, the document says.
As The Bee reported at the time, 500 people were assigned to patrol American River levees. The Sacramento, Cosumnes, Eel, Napa and Russian rivers all reached flood stages, and flood warnings were issued in El Dorado, Placer and eight other counties.
The Auburn Cofferdam broke, sending 100,000 acre-feet of water (about 32.5 billion gallons) raging into Folsom Lake.
The 2011 hazard mitigation plan says that since its 1956 completion, Folsom Dam has prevented three “potentially catastrophic floods.” The 1986 flood exceeded the dam’s flood design by about 20 percent, the county plan notes.
The flood and damages prompted the county to develop large-scale levee improvement projects.
Pineapple Express is an unofficial weather term signifying a strong atmospheric river system coming from the Hawaiian region.
Property damage: $400 million throughout California.
Mudslides close I-80 and Highway 50, 2006
Warm winter storms flooded the Feather and Sacramento rivers and many of their tributaries, breaching or overtopping levees. Major roads were closed and mudslides emerged.
Interstate 80 shut down for several hours near Fairfield due to flooding. Eastbound I-80 and both directions of Highway 50 were closed for more than 24 hours due to a “massive” mudslide between Sacramento and Reno/South Lake Tahoe.
Heavy winds closed also closed local airports, making travel difficult or impossible for many.
Property damage: $4.5 million in Sacramento County.
Levees break and Arden floods, 1997
Heavy rain in January 1997 broke 20 protective levees along the Cosumnes River, flooding 33,000 acres of cropland and 84 residences near the town of Wilton on Jan. 2, requiring rooftop rescues by boat and helicopter, county documents say.
One person died on a bridge across the river. Nine total deaths were reported across California’s Central Valley, and 120,000 residents were evacuated. Total floodwater across the Central Valley was about 250 square miles.
Later in the month, 1,000 homes in the Arden-Arcade area were flooded as Chicken Ranch Slough overflowed. Four days later, it overflowed again, damaging 500 more.
Property damage: $4.4 million in Sacramento County.
The Great Inundation, 1850, and the Great Flood, 1862
Less than two years after an influx of gold rushers settled in Northern California, Sacramento was soaked by 4.5 inches of rain the first week of 1850, according to one doctor’s measurement.
As recalled by the Sierra Sun in 2014, the first “Great Flood” or Great Inundation of 1850 was the first Sacramento flood to be accurately documented. The water rose fast, “muddying city main streets and leading some people to travel them by canoe,” the paper wrote.
With no levees at the time, a “vast amount of property was destroyed and many of the town’s lighter buildings washed away,” the Sierra Sun wrote.
Lithographs from 1850 show people canoeing along Sacramento streets, which are flooded within a few feet of some buildings’ rooftops.
A decade later, weeks of rain and what’s now known as atmospheric river system hit Oregon, Nevada and California from December 1861 to January 1862.
January 1862 is the wettest month ever recorded in Sacramento at 15.04 inches.
Property damage: Unknown.
Bonus: The rainiest day ever, 1880
The official record for 24-hour rainfall in Sacramento was set April 19-20, 1880.
The young city was drenched with 7.24 inches, and county documents say there were accounts of streets “having the appearance of miniature rivers.”