A report from the Center for Catastrophic Risk Management alleged that green spots at the Oroville Dam suggest it could be leaking.
The UC Berkeley research group released the 124 page report Thursday. In it, author Robert Bea wrote that documented images of wet spots and vegetation near the left abutment on the backside of the dam suggest the Oroville Dam could be facing a breach danger from a slow motion leakage failure.
The Department of Water Resources (DWR) has responded to green spot allegations, saying it is a natural spring from the rain. Bea responded, saying the photos show water flowing uphill, which doesn't happen with natural springs.
The report alleged that the DWR asked the Federal Energy Commission to move a test drill near the leakage in 2016 but did not mention it to the public.
Bea called for an independent investigation into the soundness of the dam.
The report went on to analyze possible causes for the spillway failure in February. Bea wrote the DWR had multiple reports of issues with the base slabs, including improper steel reinforcements, ineffective water stop barriers and ineffective ground anchors, as well as other damages and decaying areas around the spillway.
It alleged the DWR made repeated ineffective repairs, allowed large trees to grow where roots could intrude below the slabs and put off major repair work.
The report compiled several recommendations to improve safety and efficiency around the dam.
Bea suggested the DWR be provided with additional resources so it can meet the System Risk Assessment and Management (SRAM)-based standards and guidelines and adopt SRAM technology.
It was compiled by Bea, Tony Johnson and volunteers from the University of California Berkeley. Bea said input from several retired DWR engineers, maintenance workers and operators went into creating the report.
Oroville Dam spokeswoman Erin Mellon told the Sacramento Bee that the state would make sure Bea's report is shared with the independent forensic team that was hired by the state to conduct a study of what caused the spillway to collapse.
The full forensic report will be available in the fall.