Dam management concerns residents
Study shows structure could fail after a major earthquake
MORGAN HILL — Concerns about the Santa Clara Valley Water District’s management of Anderson Dam bubbled to the surface at a meeting Wednesday night to update the public on a project to replace the structure, which spilled over in February for the 11th time in its 67-year history, resulting in some of the worst flooding San Jose has seen in recent memory.
Years in the making, the $400 million project is the product of studies that found the 240-foot-tall earthen dam could fail in a major earthquake and send a wall of water down Coyote Creek.
Larry Davis was among the 150-plus people who attended the meeting at the Morgan Hill Community and Cultural Center. He blasted district officials for not installing pumps in the interim to help drain the reservoir behind the dam when it fills past 68 percent, the maximum level set by the California Division of Safety of Dams because of its vulnerability.
“You people have no emergency plans, no foresight, and I think you’d better get on it,” the 69year-old San Jose resident said.
Currently, the district’s only way to regulate water levels is an outlet pipe with a maximum flow of 425 cubic feet per second. The pipe was fully opened on Jan. 9 in the midst of the wettest water year in 122 years of record keeping in the state, but it wasn’t enough to keep the reservoir from reaching capacity and spilling over on President’s Day weekend.
The uncontrolled influx of water into Coyote Creek resulted in widespread flooding and the evacuation of an estimated 14,000 San Jose residents.
“You’ve known for years that the existing one pipe that drains the dam in a rain year does not have the capacity to keep that dam at a safe mandated level,” Davis told district officials. “Yet, for years, you have completely ignored or were not aware of any emergency plans to bring in industrial, commercial-grade pumps with enough pipe to drain the dam at a controlled rate so that it does not go over the spillway and create havoc.”
Davis’ remarks drew ap- plause from attendees.
In response, district officials said the dam and outlet pipe were built to the standards of the day in 1950, when the area was known as the Valley of Heart’s Delight, not Silicon Valley.
“This is what was required,” said Katherine Oven, a deputy operating officer for the district.
The new dam will have two outlet pipes capable of expelling up to 5,000 cubic feet per second of water, Oven said.
Depending on how much rain falls this spring, the reservoir could remain above the 68 percent mark until early May.
The district is investigating the possibility of adding pumps in the interim, but the highly pressurized pipes that would carry water out of the reservoir could potentially burst and cause rapid erosion of the dam, said John Varela, chairman of the district’s board of directors.
“We are listening to people that are suggesting what you suggested,” Varela told Davis, “but there are regulatory agencies that are suggesting to us that we cannot do that.”
Officials noted that the district has a dam safety program, which includes maintaining emergency response and preparedness plans. Information about the program is available at www.valleywater.org.
Other attendees criticized the district for not issuing an evacuation order prior to the flood in February.
“We don’t call the police. We don’t tell you to evacuate,” Varela replied. “That’s up to the various jurisdictions such as the cities and the county, and they did what they did.”
The district also drew heat for the cost and timetable of the project, which is expected to break ground in 2020 and take four years to complete. Oven acknowledged that while the dam took just $3 million and nine months to build in 1950, not as much was known then about potential seismic impacts and there were fewer regulatory hurdles to clear.
“Sometimes knowledge is power,” Oven said. “Also, sometimes knowledge makes you do things more carefully. We’ve got 2 million people living in the area below the dam.”
The district is working as quickly as it can, said Hemang Desai, who oversees dam safety for the district.
“We are very serious about public safety and we are trying to aggressively complete this project,” he said.