Commentary: Safety concern at Milliken Dam

From the Napa Valley Register, this commentary by Napa residents John Stephens and Chris Malan:

“While researching the possibility of restoring stream flows and fish habitats on Milliken Creek, we found a serious safety issue for people who are living downstream of Milliken Dam. We found that the 110-foot high Milliken Dam, which was built in 1924, should be reassessed for seismic safety.

The Green Valley Fault runs just one mile from the dam site and is capable of producing a 6.5 earthquake. The state of California Division of Dams and Safety found that Milliken Dam at full capacity “would be overstressed by seismic loads associated with the maximum credible earthquake.” Stress fractures and cracks in the face of the dam have become problematic. If an earthquake magnitude of 6.5 occurs, dam failure could occur.

The California Division of Dams and Safety ordered the city to lower the level in May of 2001. The city submitted a detailed analysis showing that “acceptable dam stresses” could be achieved with a lowered reservoir storage elevation at 907 feet, 16 feet below the crest, and still hold 1,390 acre-feet of water. After four years of engineering studies and no public reviews, four 18-inch holes and one 24-inch hole were drilled at elevation 907 to maintain the mandated level of water at the dam face. … “

Read more of this commentary by clicking here.

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