Erosion near an Oroville reservoir emergency spillway was first predicted in court documents filed by environmentalists more than a decade ago.In a technical memo on Lake Oroville’s discharge, the Yuba County Water Agency wrote in 2002 that if the Department of Water Resources used the emergency spillway, “extensive erosion would take place” and that “the spillway road and possibly high voltage transmission towers would be impacted,” according to a motion to intervene on the licensing filed by environmentalist groups in 2005.
“Because the area downstream from the emergency spillway crest is an unlined hillside, significant erosion of the hillside would occur,” the document said.
According to the California Department of Water Resources, that’s exactly what happened. After the dam’s main spillway was damaged, engineers decreased its output to save Pacific Gas & Electric lines and prevent ...