California Dam Putting More Than 50,000 Homes at Risk

February 21, 2017

Days after thousands of people were allowed to return to their homes near Lake Oroville, Calif., more than 50,000 homes remain at risk of flood damage, according to analysis released last week by CoreLogic.

If all of the homes located within six counties that surround the Oroville Dam were to sustain flood damage, the analytics provider estimates the reconstruction would cost $13.3 billion.

According to CoreLogic’s analysis, only 12 percent of the homes at risk are located in a Special Flood Hazard Area designated by the Federal Emergency Management Agency.

Figure 1: Total Homes at Risk and Reconstruction Cost Value by County

County Number of Homes Estimated RCV
Butte 15,750 $3,368,371,427
Colusa 2,344 $633,516,296
Glenn 42 $8,202,197
Sutter 25,504 $7,604,338,675
Yolo 262 $64,058,854
Yuba 6,145 $1,584,443,943
TOTAL 50,047 $13,262,931,392

Figure 2: Total Homes at Risk and Reconstruction Cost Value by City and ZIP Code

City Zip Number of Homes Estimated RCV
Yuba City 95993 10,384 $3,444,062,491
Yuba City 95991 10,293 $2,901,591,425
Oroville 95965 6,867 $1,387,826,184
Oroville 95966 4,528 $912,344,538
Marysville 95901 5,237 $1,369,704,343
Gridley 95948 3,122 $810,017,464
Live Oak 95953 2,950 $768,036,402
Colusa 95932 2,052 $577,478,166
Sutter 95982 1,143 $314,284,022
Biggs 95917 990 $231,498,912
TOTAL 47,566 $12,716,843,947

The majority of homes at risk are between 20 and 60 miles from the dam, totaling 33,967 properties with an estimated RCV of $9.8 billion. Additionally, there are 16,080 homes at risk of damage less than 20 miles from the dam with an estimated RCV of $3.5 billion.

Possible Factors in California Dam Crisis

Lake Oroville is roughly 75 miles north of Sacramento and 25 miles southeast of Chico, Calif. The dam is the tallest in the United States. Thousands near the lake were evacuated after engineers noticed a crevice in the spillway.

The Oroville Dam crisis in California demonstrates the crucial need for infrastructural updates and the importance of dam maintenance, especially spillways, according to Baldwin Wallace University geology professor Carrie Davis Todd, Ph.D. Her past research includes looking into the historic Johnstown, Pa., Flood of 1889, which involved spillway issues that caused the catastrophic collapse of the South Fork Dam. Dr. Todd, who has also conducted research in the area of precipitation change relating to climate change, which may be a contributing factor for the record reservoir levels seen in Lake Oroville.

People watch the gushing waters of the Feather River from the town’s fish hatchery a day after an evacuation was lifted Wednesday, Feb. 15, 2017, in Oroville, Calif. (AP Photo/Marcio Jose Sanchez)

According to CSU Channel Islands Professor Sean Anderson, Ph.D., who specializes in environmental science and resource management, the Oroville Dam crisis is absolutely linked to climate change.

Dr. J. David Rogers, an expert on the impact of natural disasters, and the Karl F. Hasselmann Missouri Chair of Geological Engineering at Missouri University of Science and Technology in Rolla, Mo., is an expert on identifying and evaluating natural perils, including flooding problems, dam and spillway structures and rock slope stability phenomena. Rogers suspects the issues with the Oroville Dam spillway has to do with how well the spillway’s concrete floor was attached to its foundation.

“When you build something 3,000 feet long, you have to think about cumulative shrinkage of the concrete, and if the structure is founded on a sloping ground, you need to employ some sort of structural system to resist gradual downslope creep,” he said.

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