West Shore Lake Oroville Lineament Geologic Investigation, Northern California, Part 1 of 2

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

The California Department of Water Resources (DWR) owns and operates the California State Water Project (SWP). The SWP comprises more than 700 miles of canals, pipelines, and tunnels as well as 34 storage facilities, 30 dams, 23 pumping plants, and 9 hydroelectric power generation plants all spanning two-thirds of the length of California. It supplies water to more than 26 million people throughout California. SWP water also irrigates about 750,000 acres of farmland, mainly in the San Joaquin Valley.

The flagship structure of the SWP is Oroville Dam, part of the Oroville-Thermalito Dam Complex. At 770 feet, Oroville Dam is the tallest dam in the United States and the most voluminous dam in California. Oroville Dam was constructed between 1961 and 1967. The reservoir filled for the first time in 1968. Power generation from Oroville Dam is regulated by the Federal Energy Regulatory Commission (FERC).

On August 1, 1975, the ML 5.7 Oroville earthquake occurred along the Cleveland Hill fault (CHF) damaging the town of Oroville, located a few miles downstream of Oroville Dam, and causing little to no damage to the dam. The Oroville earthquake resulted in previously unrecognized Quaternary fault activity along the foothills of the northern Sierra-Nevada.

In December 2014, Independent Consultants for FERC recommended that DWR inspect the northern projected trace of the CHF to determine whether the fault continues north passing less than one mile upstream of Oroville Dam.

In 2015, DWR began a phased geologic investigation of the northern projection of the CHF. Due to several years of drought, low reservoir water levels allowed opportunity to view shoreline areas typically submerged. Using LiDAR, supplemented with multi-beam survey data, DWR identified anomalous geomorphic features resembling active faults north of the mapped trace of the CHF along the West Shore of Lake Oroville (WSLO).

Presenting Author: Don F. Hoirup

Authors