Tuesday, 14 February 2017

Americas tallest dam about to burst.

An aerial view of the damaged Oroville spillway in Oroville, Calif.  (Photo: California Department Of Water Resources via European Pressphoto Agency)

The Oroville Dam is the tallest dam in the USA and is a critical piece of the state’s water system.
Oroville Dam is in the foothills of the Sierra Nevada east of the Sacramento Valley about 150 miles northeast of San Francisco.

The dam, which was completed in 1968, has risen rapidly this winter as the Feather River and its tributaries have gushed down swollen after storms that brought heavy rain and snow. The storms, which came after more than five years of severe drought, have led officials to release water from various dams across Northern California.
A gaping hole appeared in the dam’s main spillway last week, and that prompted state officials to begin releases over the emergency spillway for the first time in the reservoir’s history.
Though the dam itself remains intact, erosion damage to the emergency spillway raises the potential of that spillway failing and unleashing an uncontrolled torrent of floodwaters.
Trying to head off a disaster, state officials increased the flow down the dam’s main spillway Sunday night. Their efforts to deal with the crisis could determine not only whether entire towns are inundated but also whether the state’s second-largest reservoir emerges with manageable damage or something much worse.

At least 188,000 people living downstream of California's Oroville Dam were ordered to evacuate late Sunday over concern that a damaged emergency spillway could cause severe flooding.

(story USAToday)

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