Following concerns at the weekend of uncontrolled releases from Lake Oroville auxiliary spillway in California, US, the state Department of Water Resources last night said that the primary spillway at Oroville Dam continues to flow at 100,000ft3/sec and lake levels have dropped to 894ft. 

After evaluating the erosion on the emergency spillway, a plan was put in place to prevent further erosion, the department said in a statement. Utilizing trucks and helicopters, crews moved large rocks and gravel to fill erosion on the emergency spillway. Department staff continues to inspect and evaluate the emergency and primary spillways for further erosion.

Total discharges from the reservoir remain consistent with flood control releases at this time of year under these weather conditions, it added, stating that it does not expect the discharge from the reservoir to exceed the capacity of any channel downstream.

Evacuation orders still remain in place in the area as repair work is being undertaken.

The tallest dam in the US – Oroville Dam – is sound and is a separate structure from the auxiliary spillway.