California’s Tallest Dam, Oroville on the verge of Disaster

Published On:February 14, 2017, 2:34 pm

California’s Tallest Dam DisasterAlmost 12 years ago the environmental groups had issued a warning that the nation’s tallest dam in California was an impending disaster.

The experts were concerned that heavy rain along with fast-rising waters could overpower the prime concrete spillway of the Oroville Dam, and overflow the emergency spillway and eventually flood residents downstream.

However, all of their warnings were ignored, and last weekend some of the warnings raised by them were realized.

Policy director with Friends of the River, Ron Stork, a Sacramento environmental group, mentioned that federal and state officials were asked to reinforce the spillway.

Stork said, "We urged them to put concrete on the spillway -- our argument was that without a proper spillway, the hillside would wash away and cause catastrophic flooding."

There were a series of storm events happened this month which resulted in the partial failure of the dam that renders flood control for the region.

Blake Paul Tullis, a professor of Civil and Environmental Engineering at Utah State University, said, "Extreme hydrologic events precipitated this near-disaster."

The very first strong storms dumped snow and rain across California. The high waters made the water level of Lake Oroville to escalate to the top, and the excess water could not be drained on time.

There was an erosion which left a hole which was almost the size of a football field and a minimum 40 feet deep in the main concrete spillway.

Tullis said, "Any spillway, primary or emergency usually has some kind of protection, a concrete basin, for structures as big as this, it seems pretty uncommon to not have some protection at the base of the spillway."

The state authorities have called for a mass evacuation for some 200,000 people, out of concern that eventually the spillway could break and the gushing water would come downstream. These sudden evacuation made the residents panic.

Stork said on Monday, "It was a slow moving crisis that picked up a lot of speed yesterday."

According to Stork he saw this coming back in October 2005 itself, when Friends of River, along with the Sierra Club and the South Yuba Citizens League, filed a motion along with the Federal Energy Regulatory Commission (FERC) as part of Oroville Dam's re-licensing process.

There was an argument in the motion that the Oroville Dam that was completed in 1968, did not meet the appropriate safety standards.

The auxiliary spillway was made to work with a replacement dam which was never built. Without the newly built dam, the Oroville Dam’s auxiliary spillway was meant to be used in an infrequent and controlled way and in an emergency capacity.

Their motion was declined by the energy regulatory commission to reinforce the emergency spillway with concrete. According to Stork, money was the problem.

A reply filed by the Metropolitan Water District of Southern California and the State Water Contractors stated that FERC, which is responsible for issuing licenses, was not able to pay for the damages needed for the upgrades.

Bill Croyle, wgo is the acting director of the California Department of Water Resources said that he was "not familiar with 2005 documentation or conversation" pertaining to the spillway worries.

On Monday, at a news conference Croyle said that no water was overflowing the emergency spillway and also the levels of the lake were constantly dropping.

Officials stated that, crews members were bagging and breaking chest high bag of rocks in the hole which is eroded in the auxiliary spillway.

According to Stork and Tullis from the environmental group, the appropriate solution as of now is to rectify the broken main spillway in the summer.

Stork concluded by saying, "If the department is unwilling or unable to keep the reservoir down so that it does not spill, then we could face the same catastrophic circumstance again."

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