Oroville Dam Reached Capacity Faster Than Previous 16 Years

Since going over capacity last week, the water level in the Oroville Dam has dropped, but it's still at a higher level for this time of year than the previous 16 years.

The dam reached capacity causing overflowing water to go into two of the dam's spillways. But damage to those spillways created concern that they would fail and prompted an evacuation of nearly 200,000 people. The lift on the evacuation was announced on Tuesday, but because of projected high levels of precipitation for California this winter, residents are told to remain vigilant.

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California has experienced a massive drought for the past five years which led to water restrictions, tough farming conditions, and the state's dams and reservoirs not undergoing the same type of strain that was put on the Oroville Dam last week.

Dan Brekke of member station KQED told Morning Edition that the emergency spillway used to help release the extra water was used for the first time during the last week. The dam went into service in 1968, but previously the main spillway was used. Officials had to use the emergency spillway after a large hole developed in the main one, putting it out of use.

While this was the first time the emergency spillway had to be used, it was not the first time concerns were raised over how sound the dam's structure was. Paul Rogers of member station KQED told All Things Considered that people were worried about how the emergency spillway was built and potential erosion issues that could result from it being used. They made their opinions known in 2005, the same year the federal government was re-licensing the dam.

Officials have said that the levels are now low enough to contain water from the next rainstorm, but that residents should be ready to evacuate again if conditions change.