Austrian Dam Spillway Replacement

On October 17, 1989, the Loma Prieta earthquake of Richter magnitude 7.1 occurred on the San Andreas fault approximately 60 miles south of San Francisco. The San Andreas fault is the longest and most active and damage producing fault in California. Austrian Dam is located about two thousand feet from the epicenter of this earthquake, and, as a direct result of its location suffered major damage. Austrian Dam is a 1,328,000 cubic yard earthfill dam with a maximum hydraulic height of 185 feet. It was constructed in 1952 by its owner, the San Jose Water Company. The dam is located on Los Gatos Creek in the Santa Cruz Mountains in Santa Clara County, California. The dam impounds a reservoir (Lake Elsman) of about 6,100 acre feet (2 billion gallons). This stored water is treated at the Water Company's Montevina Water Treatment Plant and comprises about 10 percent of the Company's total water supply. Loss of this valuable water supply would require significant alterations to the Water Company's operation. Consequently, one of the highest priorities of the Water Company is to ensure continued availability of this facility under all circumstances, especially during times of emergency such as after an earthquake or during a drought. Both immediate temporary repairs and a complete spillway replacement were required to correct the earthquake damage. 6 pp., 5 references.