Oroville Dam Spillway Update Planned After Crack Communication Controversy

OROVILLE, Calif. (AP) - California water officials plan to update a Northern California community Wednesday about their efforts to repair the nation's tallest dam after damage to its spillways forced nearly 200,000 people to evacuate last February.

The crisis in Oroville was averted, but as the rainy winter season begins, Department of Water Resources officials will explain their efforts to ensure the area doesn't again face such a scare.

The community meeting is the first since federal officials made public their concerns about a series of hairline cracks in freshly laid concrete on the rebuilt spillway. State officials said cracking is normal and federal regulators agreed that no immediate repairs are necessary.

Oroville Mayor Linda Dahlmeier said last week the state hasn't been communicating enough with her town about the ongoing repair effort.

The trouble at Oroville Dam began in early February, when a massive crater opened up in the main spillway, a concrete chute that releases water from Lake Oroville, California's second-largest reservoir. Crews shut down the spillway for inspection just as a major storm dumped a torrent of rain in the Feather River basin. With the main spillway damaged and unused, the lake quickly filled to capacity and water began flowing over a concrete weir that serves as an emergency spillway. It had never before been used.

The water eroded the barren hillside beneath the concrete, leading to fears the weir would collapse and release a wall of water that would swamp communities and destroy levies for miles downstream.

Construction crews are racing to rebuild the main spillway and fortify the barren hillside in case the emergency spillway is ever used again - a project estimated to cost about $500 million. About a third of the spillway has been fully rebuilt, while the rest has been fortified for the winter with plans to finish next year.

Officials drained Lake Oroville about 80 feet below its typical level for the start of winter, providing extra storage for incoming water. On Wednesday, the lake was 200 feet shy of its maximum capacity.

Another meeting is planned Thursday in Yuba City, a larger community downstream from Oroville which was also evacuated in February.

Copyright 2017 The Associated Press.