California floods continue to wreak havoc

By David Jacobson, Temblor

Check your flood risk

Flooding has become so severe in parts of San Jose that some residents are being rescued by boat. (Photo by Marcio Jose Sanchez)


Even though the rain has stopped for now, the flooding in California continues to wreak havoc on residents across the state, and has taken the lives of at least 8 people. As more rain fell last night, approximately 14,000 residents fled their flooded homes in San Jose. Additionally, mandatory evacuations were in place for several thousand residents in what is described as the worst flooding event 100 years. To make matters worse, the 101 Freeway, which serves as a main commuter line from the South Bay to San Francisco, was shut this morning due to rising waters, disrupting the morning commute.

This Temblor map shows the likelihood of flooding in and around the city of San Jose.


The culprit for much of the flooding in Silicon Valley, is Coyote Creek. In addition to runoff from the harsh storms over the last week, Coyote Creek is an outlet for Anderson Lake, a reservoir that for the first time in 11 years, reached capacity. This forced the use of the Anderson Dam spillway, which accentuated flooding problems. It should be noted that normally Anderson Lake is not permitted to be at more than 68% capacity due to the seismic threat in the area. For more information on that, click here.

A waterfall is not a common sight in Morgan Hill, CA. However, due to heavy rainfall, Anderson Dam’s lower spillway is being used. (Photo by Len Ramirez / KPIX 5)


Due to heavy rainfall, the Anderson Dam spillway is being used for the first time in 11 years. The increase in water running down Coyote Creek has caused significant flooding in San Jose. (Photo by Jim Gensheimer/Bay Area News Group)


In addition to the mandatory evacuation zone in San Jose, which at its largest is 1.5 miles long and one mile wide, there is also a voluntary evacuation zone which covers a seven mile stretch along Coyote Creek. These evacuations occurred as the creek reached a record 4 feet above flood stage, sending chest-high water through neighborhoods. For 220 people this meant being rescued by boat, and in some cases people who had waded through floodwaters were sprayed with soap and water to clean off engine fuel, garbage, and sewage which has contaminated some of the floodwater.

This Temblor map shows the location of flooding along the 101 Freeway, as well as the approximate mandatory evacuation zone.


At this stage, local officials are unsure when residents will be allowed back to their homes, as flood warnings are in place until Saturday. While San Jose residents were warned about flooding, Mayor Sam Liccardo conceded that this scale of flooding was not anticipated. As we reported yesterday, the majority of areas flooded are located in zones where the likelihood is 10% in any given decade. Should more information come in on these floods, or should conditions worsen, we will continue providing updates.


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