On Sunday at least 188,000 people were evacuated from several Northern California counties due to damage at the Oroville Dam (which provides flood control for the region and is located about 75 miles north of Sacramento). At this time the nation’s tallest dam remains intact but the emergency spillway (one of two spillways), which helps to ensure that the water does not rush over the top of the dam when the levels are high, has begun to erode.
Therefore, cities and counties near Lake Oroville had a mandatory evacuation due to fears it could endanger those communities living downstream. At this time, those orders remain in effect and there is no word on when they will be lifted.
This year, Northern California has had record heavy rainfall so Lake Oroville has filled to the point of overflow. But, the lake also gets water from the northern Sierra Nevada mountain range and it is also experiencing one of its wettest seasons.
From the article:
“A light flow of water began washing into the emergency spillway Saturday and the volume of water began to increase. Around 3 p.m. local time on Sunday, authorities learned that the dam’s emergency spillway was eroding, Honea said.
The erosion of the emergency spillway is dangerous because “when you start to erode the ground, the dirt and everything else starts to roll off the hill,” said Kevin Lawson, California Fire incident commander.
“It starts to undermine itself. If that is not addressed, if that’s not mitigated properly, essentially what we’re looking at, is approximately a 30-foot wall of water,” he said.”
According to California Fire the evacuation totals were: about 35,000 people from Butte County, 65,000 from Yuba County, 76,000 from Yuba City and 12,000 from Marysville City.
Thankfully, after the evac orders were issued there was a “significant decreases in the water coming over the emergency spillway.” And as of Sunday night, the flow of water on the emergency spillway had stopped as the Department of Water Resource was able to withdraw more water from the other spillway.
More from the article:
“The primary spillway is releasing water at 100,000 cubic feet per second in an effort to reduce the amount of water traveling down the emergency spillway, authorities said. Normal flows down the main spillway are about 55,000 cubic feet per second.
“The goal is to get the lake to drop 50 feet. If we can continue to do that, that brings a little bit of calm to what we’re trying to accomplish here,” said Cal Fire’s Lawson.”
Teams will be back at it on Monday hoping to fix the issue or brace themselves for the rain that’s coming on Wednesday. We will keep you updated as new information becomes available.
Source: CNN
