First Disaster for California in 2017: The Oroville Dam Spillway corrupted
By Mai Houa Thao, Clarion Staff
The United States’ highest dam, The Oroville Dam, has brought the first misfortune to California in 2017. The Oroville Lake holds more than 3.5 million acre-feet of water, and is the second largest water reservoir in California. During the rainy season the Oroville Lake had risen by around 10 feet, and on February 7, 2017 the department of water Resource detected that the spillway was broken midway. Therefore the spillway had to be closed down for repairs, but it was not the best choice as a lot had runoff water were coming into Oroville Lake, which caused the water of the lake to rise 150,000 acre-feet above the storage level.
The Oroville Lake has another choice and that is to use the emergency spillway, but this emergency spillway hasn’t been used in 48 years, therefore The Department of Water Resources wants to try to avoid using it. This will work by re-raising; the water from the lake wants through the side of the hill, where there is many trees and bushes, down to the Thermalito Diversion Pool below. The Department of Water Resources conducted an experiment to test how much damage wills it cost to use the damaged spillway without getting to use the emergency spillway. After the experiment, they decided to let the spillway do its job of releasing water and then after that, they can be fixed the spillway. In about 48 hours the lake rose 20 acres per feet.
The Department of Water Resources’ chief Bill Croyle mentioned at a press conference that the water might actually be released through the emergency spillway. As preparation The Department of Water Resources cut down trees and removed bushes in the emergency spillway incase it would be needed to be used. The damaged spillway released 35,000 cubic feet of water per second before and now as it was raining hard and the water in Oroville Lake has risen, about 65,000 cubic feet of water have released per second as an attempt to try to stop the lake from overflowing. Around February 10 the rain stopped and made the water level drop enough to not overflow. But the next day, warm storm are causing heavy runoff into the lake. On the morning of February 11, the emergency spillway was used for the first time. Because of this overflow the water being released out of the main spillway decreased.
The Department of Water Resources says that on Monday the 13th, water will stop overflowing down the emergency spillway. As the water stopped overflowing erosion on the hillside of the emergency spillway has increased beyond The Department of Water resources’ expectation. On the 14th the main spillway is back in used and about 100,000 cubic feet of water are release per second. As so much water is poring down the spillway, the water erosion keep eating away the concrete and sides of the hill. On the 12th of February officials, had ordered evacuation from Oroville to Gridley. This evacuation had forced 180,000 people to move away from their homes. But two days later the 14th the evacuation was reduced into a warning and that all residents can return back to their homes. But as a warning the residents are to be prepared to leave if the risk of the situation increase. when the lake has dropped but the time was short, on the 16th new storms came by and as it left the lake starts to raise again. The Department of water Resource have taken care of the upcoming water raise, and starts to clear the water channel in the 19th. As he storms calms down the Department of water Resources stop the water that flows down the wrecked main spilled way, and sees a shocking destruction of the Oroville spillway. The department of water resources’ chief Bill Croyle have mentioned in an interview that the Oroville spillway have to be completely rebuilt, and it will cost around 100 to 200 million dollars.
March 3rd the dam operators used the hydropower generator again. but the very next day the power plant was shut down again, plus, there is problems down river. On the 6th the hydropower was reopened again after getting shutdown for 32 hours. The hydropower was closed because the crew workers need to deepen the river channel downstream for the power plant. Now it is still unknown whether there will be any more problem or is it safe to assumed the end of this crises.