Following the 1989 Loma Prieta Earthquake, the East Bay Municipal Utility District (EBMUD) embarked on a $200 million Seismic Improvement Program (SIP) to increase the reliability of its water system. Four of the District's water treatment plants were seismically strengthened as part of this program. These plants were built between 1919 and 1965 with a maximum capacity ranging from 163 ML/Day to 303 ML/Day. The evaluation and upgrade design of these water treatment plants was described.