MORGAN HILL (CBS SF) — The Santa Clara Valley Water District said Monday that it agrees with federal regulators’ orders to move forward with the project to drain the Anderson Reservoir to reduce risk to the public in the event of an earthquake.
The Federal Energy Regulatory Commission (FERC) demanded that the water district fully drain the reservoir by October 1, 2020. They told Valley Water that the safety risk at the 240 foot dam is currently “unacceptably high” and that they must maintain the reservoir at an elevation no higher than 565 feet.
“You must take all appropriate measures to maintain and quickly lower the reservoir to elevation 565 feet if the reservoir rises in the event of significant inflow,” wrote David Capka, director of the Division of Dam Safety and Inspections at the FERC, in a letter Thursday to Valley Water.
The Anderson Reservoir is the largest in Santa Clara County and the Anderson Dam Seismic Retrofit Project (ADSRP) aims to avoid an uncontrolled release of water from the dam if it’s damaged by a large earthquake.
The large potential water runoff could damage cities and rural areas from the San Francisco Bay to the north through Monterey Bay to the south, including much of Silicon Valley, Valley Water said.
Since 2009, Valley Water has kept the dam’s water level to at most 74 percent of capacity after learning the dam could fail in a 7.2 quake. The reservoir is built along the Calaveras Fault.
A priority of the ADSRP is to design and construct a large outlet pipe to provide greater control over the water levels and to increase public safety when an earthquake eventually strikes.
But the project is “complicated and time consuming,” Valley Water said in a statement Monday. The water district said it is working with state and federal agencies to secure the proper permits for the project while complying with federal rules and regulations.
The project could also come with “unsafe consequences,” including potential damage to the intake structure of the Anderson Reservoir, which would give the district “no way to control water flows out of the reservoir, potentially impacting downstream communities.”
Valley Water also said the project could significantly impact wildlife in the ecosystem surrounding the reservoir, including “sensitive native fish, amphibians, reptiles, wetlands, and riparian habitats.”
Water quality could also be significantly impacted downstream from the dam.
“We agree that the health and safety of residents is the number one priority. That is why Valley Water, with agreement from the FERC mandated independent Board of Consultants, put forward an operations plan on Oct. 31, 2019, that we believe would best decrease the risk of water reaching unsafe levels,” Valley Water said.
Patrick Ferraro, an environmental studies lecturer at San Jose State University, was on the water district board for two decades. He says the area is equipped with enough water resources, including three aqueducts, even with the threat of a drought looming.
“We should not be worried about running out of water,” Ferraro said. “We have water stored undergruond, we also have remote water storage in Kern County.”
He said that due to the large amount of carryover storage, then the county should have adequate water “unless the drought goes on for more than seven or eight years.”
The water district serves two million customers, who may have to conserve water use, especially if California officially enters a drought in the coming months. The water district is exploring other sources of water that will have to come from outside the county.
A bill has been introduced to California lawmakers that would move the project along as quickly as possible.
KPIX 5’s Maria Medina contributed to this report.