For the first time in its history, the Oroville Dam authorities had to use the emergency spillway. This decision was taken after the water levels were seen to rise dangerously high. This event was caused by various factors.
The Oroville Dam is located in Oroville, California. It is an embankment dam and was built on the Feather River. Being 770 feet high, it is considered the tallest such formation in the United States.
Oroville Dam impounds the Lake Oroville. It serves several functions. Mainly, it is used as a water supply. And also as a hydroelectricity generator. Or as a flood control. Just recently, this latter function has been increasingly necessary.
The dam was built and is managed by the DWR. This is the California Department of Water Resource. It is also one of the main elements of the SWP. This is the California State Water Project.
Over this past week, the Oroville Dam authorities have been facing an unexpected and undesired event. The officials had to activate the dam’s emergency spillway. An obligatory element, this has nonetheless never been used. This is its first ever utilization.
According to reports, the problems started on Tuesday. At the time, a primary spillway section collapsed. This primary spillway is basically a concrete channel. It is over 3,000 feet long and about 180 feet wide. The collapse took place amidst high-volume water releases.
Recently, the area has been facing quite a number of storms. Which also caused mountain runoffs. Both elements combined and led to the swelling of the lake waters.
Following the Tuesday collapse, the resulting hole continued to grow. Crater-like in appearance, it has since greatly expanded. As such, the Oroville dam authorities decided to ease the amount of water released through the main spillway.
Which led to the current situation. As the water levels still have to be controlled, officials turned to the emergency channel. This will help them prevent the lake from overflowing. Due to the increased water levels, they could have potentially spilled over the dam top.
This emergency spillway is a rather more basic variant. It basically is an open hill. This drains towards the river. And has never once been used. Which is quite a feat considering the dam’s age. The Oroville Dam was built back in 1968.
State officials were reluctant to use this emergency channel. Amongst others, they feared that the rushing waters could break the hill vegetation. Which would then be carried away and potentially cause other damages.
Nonetheless, dam crews started taking precautionary measures. They proceeded to clear away the channel of trees, brush, and various other debris. This was proven to be a good decision. Late on Friday afternoon, authorities were hoping to control the water flow via the main spillway.
But by Saturday morning, they decided to turn to the emergency one. This was a necessary action as more water had to be liberated from the dam’s lake.
As of Saturday, the lake authorities have been using both spillways. Even the damaged main one is still in use. Although its capacity is somewhat lower. According to the authorities, the spills are not likely to cause problems. They are not likely to lead to flooding.
The Feather River capacity is rated bigger than what is currently being streamed into it.
As of Saturday, the cause of the main spillway rupture remains unknown. It may be established as the spilling process comes to a stop.
The emergency spillway was activated early on Saturday morning. Reportedly, it will continue being used throughout the weekend. And even across Sunday night, perhaps even more.
State officials had hoped that it would not be necessary. And they never wished to use. But nonetheless, the emergency channel is performed according to expectations. Even if it’s first ever use.
Image Source: Wikimedia