Despite falling water levels, there is still concern for Oroville Dam
The evacuated residents near the Oroville Dam are allowed to return home, but there is still cause for concern. More rainfall is expected for the region, as forecasters are expecting another 2 to 3 inches of rain over Oroville, and an additional 9 inches of rain upstream from the dam through next Tuesday.
The forecasted rain is not as serious as the 12 to 20 inches of rain that fell on the area last week, but it’s still concerning for the damaged dam.
It’s this recent influx of rainfall that caused the dam to use the emergency spillway for the first time in its nearly 50 year history. This comes following damage to the main spillway, after the swift moving water created a gaping hold nearly 50 feet deep and 250 feet long.
What caused this and why it never happened before in the history of the dam are the questions that are being asked. The short answer is erosion, which is the combination of wind and water to breakdown particles. The longer answer is that the dam has never had to face flooding of this magnitude and state agencies were acting in accordance with the best information they had available.
The goal now is to prevent the dam and its damaged spillway from eroding any further. This is being done by allowing the original spillway and emergency spillway to release double the amount of water than previously.
If the dam were to fail, it would cause the concrete wall to fall and release a 30-foot wall of water that would cause catastrophic flooding. State agencies say luckily for now, the erosion has stabilized.
