Updated: Oroville Main Spillway Closed, Unexpected Closure of Both Systems

Picture NewCali News

Updated April 11, 2019 11:30 pm

The Oroville dam spillway system was suddenly and unexpectedly shut down after 12:00 pm pst Thursday April 11, 2019. As of this writing there is equipment on the main spillway. At this time there is no explanation as to why the complete shut down of the Hyatt power plant and the main spillway occurred or the nature as to why there appears to be equipment on the spillway deck making repairs.

According to Oroville Mercury-Register there was a planned shutdown.

From the Wednesday April 10, 2019 edition:

"OROVILLE — The state Department of Water Resources stopped releases from the Oroville Dam spillway on Wednesday because of forecasts showing upcoming dry weather.

The department said releases were halted at 1 p.m. on Wednesday. Outflows from the newly reconstructed spillway started at 8,300 cubic-feet per second, or cfs, on April 2 and peaked at 25,000 cfs on April 7.

“Releases over the past 10 days have provided adequate space in the reservoir to help provide flood protection,” said Erin Mellon, assistant director of public affairs, in a written statement. “DWR’s experts, state and federal regulators have concluded the main spillway performed as designed. Once the spillway gates close, a team of engineers will inspect and assess the spillway, and continue to monitor the instrumentation and share those updates with the regulators.”

What was not expected was the complete shut down of both the Hyatt power plant releases and the main spillway. DWR records show that both systems were stopped at 3:00 pm April 11, 2019. Later the system in the Hyatt power plant resumed.

The picture above shows the spillway partially closed but not completely sealed. DWR officials were unable to completely seal the main gates and were forced to expose workers who appeared on the spillway surface to work in several inches of water streaming in a thin sheet down the spillway.

The spillway on the right side dried enough to expose the spillway seams. As the picture above indicates there was a chalky substance that streamed down the spillway in the area where workers were seen using equipment.