A two-fer - first from San Jose, CA's The Mercury News:
Oroville Dam: Feds and state officials ignored warnings 12 years ago
More than a decade ago, federal and state officials and some of California’s largest water agencies rejected concerns that the massive earthen spillway at Oroville Dam — at risk of collapse Sunday night and prompting the evacuation of 185,000 people — could erode during heavy winter rains and cause a catastrophe.
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.
Much more at the site - it all boils down to politics and money. Over 3,000 comments - lots of good ones.
Second, from the Los Angeles Times:
Here's the nightmare scenario at Oroville Dam that officials are fighting to prevent
Any dam engineer would be terrified of this nightmare scenario — the possible collapse of a retaining wall in California’s second largest reservoir.
That’s the prospect officials faced when they ordered more than 100,000 people evacuated downstream of the nation’s tallest dam Sunday.
It occurred insidiously: a pocket of erosion that crept ever closer to a low concrete wall that was supposed to be the last, best defense against disaster.
The threatened concrete structure, called a weir, was designed as an emergency escape route of sorts for rapidly rising waters at swollen Lake Oroville. By allowing some water to spill over its shoulders, the concrete wall would relieve tremendous pressure building on Oroville Dam itself, which is located nearby.
And there is another big storm heading their way - expected to hit sometime this weekend.
