Officials were warned twelve years in advance about potential safety hazards at the Oroville Dam in Butte County, California, which now faces the risk of flooding nearby residential areas as a result of a broken spillway and increased rainfall.
Local outlet Mercury News reports:
“Three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government on Oct. 17, 2005, as part of Oroville Dam’s relicensing process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.”
That never happened. The aging Oroville dam, which exceeded capacity on Sunday, began to overflow and spill over the earthen emergency spillway after the main spillway was severely damaged. These developments prompted flood warnings and a declaration of a state of emergency from Governor Jerry Brown. The spillway is on the verge of collapse, a potential disaster that prompted mass evacuations. Over 188,000 residents have been displaced.
The environmental groups’ 2005 filing with the Federal Energy Regulatory Commission expressed concern over the exact situation at risk of unfolding now. They warned that in the “event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as ‘loss of crest control.’”
According to Ron Stark, policy director with Friends of the River, “We said ‘are you really sure that running all this water over the emergency spillway won’t cause the spillway to fail?’ They tried to be as evasive as possible. It would have cost money to build a proper concrete spillway.”
Indeed, FERC dismissed their filing “after the state Department of Water Resources, and the water agencies that would likely have had to pay the bill for the upgrades, said they were unnecessary.”
Though by Sunday evening officials reported water was no longer spilling over the emergency spillway, they are continuing to release water through the regular, damaged spillway at a rate of 100,000 cubic feet per second, which they claim is consistent with “normal flood control releases.” Footage from local affiliate Fox40 shows the Feather River, which is receiving much of the water releases, is brimming. They report it “looks more like a lake today,” though for now, officials say Feather River remains below flood stage.
According to Fox40, officials with the Department of Water Resources say “they have not been able to access the area on the emergency spillway that has been eroded.”
Officials are scrambling to continue clearing water and repairing the damaged spillway, as more storms are expected on Wednesday and Thursday.
Butte County Sheriff Kory Honea said officials are working on a “repopulation plan” for evacuated residents, though they offered no time-table, asserting instead they will allow people to return when it is safe.
Regardless of the outcome, the ongoing incident has undoubtedly demonstrated gaping flaws with the methods government agencies use to maintain aging infrastructure.