As California experiences a doubtlessly record-breaking dry February, federal regulators have ordered that a big reservoir south of San Jose be drained attributable to fears a dam might collapse in an earthquake, sending a torrent of water into Silicon Valley.
The Federal Energy Regulatory Commission ordered final week that the Anderson Reservoir be utterly drained by Oct. 1 attributable to fears the 240-foot excessive earthen Anderson Dam poses too nice a danger of collapse if a big earthquake strikes.
“It is unacceptable to maintain the reservoir at an elevation higher than necessary when it can be reduced, thereby decreasing the risk to public safety and the large population downstream,” David Capka, director of FERC’s Division of Dam Security and Inspections, wrote in a letter Thursday to the Santa Clara Valley Water District, which owns the reservoir.
Anderson Reservoir was inbuilt 1950 between San Jose and the group of Morgan Hill and may maintain 90,000 acre-feet of water. The reservoir is the biggest in Santa Clara County and holds greater than half the water district’s capability in all of its services.
Since 2009, the dam’s water stage has been stored at a most of 74 % of capability due to an evaluation that it might fail in a 7.2 magnitude quake or stronger. The reservoir is constructed alongside the Calaveras Fault. On Monday, amid the threat of another drought in California, Anderson Reservoir was simply 29 % full.
A seismic retrofit undertaking has been underway due to its state classification in 2017 as being an “extraordinarily excessive” downstream hazard.
“Research have proven a big earthquake might injury Anderson Dam, inflicting an uncontrolled launch of water that would inundate cities and rural areas from San Francisco Bay south to Monterey Bay, together with a lot of Silicon Valley,” according to the water district.
In 2019, Valley Water produced a video depicting a worst-case situation if a filled-to-capacity Anderson Dam failed within the occasion of a significant earthquake, which confirmed main flooding in Coyote Creek that stretched all the way in which to San Jose. Coyote Creek flows from the dam by way of downtown San Jose to San Francisco Bay.
The specter of flooding is recent on the minds of many within the area. Greater than 14,000 residents needed to be evacuated in 2017 as water from swollen Coyote Creek flooded properties and quickly shut down a portion of a freeway, based on The Related Press.
On Monday, the water district stated it agreed with the federal fee’s evaluation the reservoir ought to be drained forward of the “difficult and time consuming” retrofit undertaking.
“Valley Water has been working with a number of state and federal businesses by way of the years to safe the right permits because the scope of the undertaking has elevated attributable to extra security and design necessities,” Valley Water CEO Norma Camacho stated.
“A precedence shall be to design and construct a big outlet pipe, which can present larger management over the water ranges and improve public security,” she added within the assertion.
Camacho stated draining the biggest reservoir within the district will probably kill wildlife downstream in Coyote Creek, together with endangered steelhead trout, amphibians and reptiles.
Along with environmental impacts, a dry winter has the Golden State doubtlessly heading into a brand new drought.
Saved water is a crucial a part of the south San Francisco Bay Space’s provide — with sufficient water for the annual wants of no less than 130,000 folks in addition to what the district considers an emergency provide.
“Whereas residents have finished a wonderful job of conserving water since 2013, one other drought throughout this timeframe might require everybody to considerably lower their water use,” Camacho stated.
The company is exploring different sources of water from outdoors Santa Clara County, corresponding to from main reserves in Kern County, Valley Water District Government Nina Hawk told KTVU.
“That is greater than we’d use in a single yr,” Hawk stated. “That water is out there for us to convey into the county to be used for our residents coming into this yr,”
Since clients have enormously lowered water use as a matter of behavior after the latest drought, officers consider they’ve greater than sufficient water to satisfy regular utilization whereas retrofitting of the large dam is ongoing.
“It is anticipated that this building might take wherever from two to doubtlessly 5 years however it’s decided upon the allowing course of, the environmental laws and be sure that we accomplish that in a secure method and we accomplish that in compliance with the legal guidelines and the laws,” Hawk instructed KTVU.
As a part of the reconstruction course of, the Anderson Dam shall be partially deconstructed and its infrastructure changed with stronger supplies earlier than it’s recovered with earth to finish the method. This course of is alleged to be a sooner and extra financial substitute than if the earth, metal, and concrete had been used, based on KTVU.
The Related Press contributed to this report.