California Dam Failure Evacuation Planning Program

On March 12, 1928 the St. Francis Dam failed, killing 450 people. This single event resulted in the second greatest loss of life in California history, next to the San Francisco earthquake and fire of 1906. Shortly after the failure of St. Francis Dam, the state legislature passed a law providing for the supervision of all non-federal dams in the State. Specifically, this legislation provided for (1) examination and approval or repair of dams completed prior to the effective date of the statute, August 14, 1929; (2) approval of plans and specifications, and supervision of construction of new dams, and of the enlargement, alteration, repair, or removal of existing dams; and (3) supervision over maintenance and operation of all dams of jurisdictional size. Jurisdictional size dams are those artificial barriers, together with appurtenant works, which are 25 feet or more in height or have an impounding capacity of 50 acre-feet or more. Any artificial barrier of 6 feet in height or less, regardless of storage capacity, or with a storage capacity of less than 15 acre-feet, regardless of height, is not considered jurisdictional. (See accompanying diagram.) On December 14, 1963, the Baldwin Hills Dam, located in the Los Angeles area, failed, causing 5 deaths and forcing the evacuation of 1600 residents downstream. The legislature then amended the Water Code to include both new and existing off-stream storage facilities within the State's jurisdiction. On February 9, 1971, the San Fernando earthquake caused the partial failure of the Lower Van Norman Dam. A precautionary evacuation of 80,000 Santa Ana residents downstream and an immediate drawdown of the reservoir was undertaken to avert a disaster. In responding to this event, the State Legislature added Section 8589.5 to the Government Code. 6 pp., 4 references. [Also presented at Dam Safety 1991]