Santa Fe Dam

Santa Fe Dam and Reservoir is a flood control project constructed and operated by the U.S. Army Corps of Engineers, Los Angeles District. Construction of the project started in August 1941, but temporarily interrupted in 1943 in deference to military work. Construction resumed in 1946, and the embankment and the spillway were completed in February 1947. Installation of the slide gates was delayed by post-war metal shortages until January 1949. The project is located on the San Gabriel River about 4 miles downstream from the mouth of the San Gabriel Canyon. The San Gabriel River originates on the southern slopes of the San Gabriel Mountains. It flows through precipitous canyons to the base of the mountains, thence across a broad alluvial cone to Santa Fe Reservoir, and through the San Gabriel Valley to Whittier Narrows Reservoir. The Rio Hondo, a distributary of the San Gabriel River, branches from the river just below Santa Fe Dam and flows westward to Whittier Narrows Reservoir. From Whittier Narrows Reservoir, the San Gabriel River flows south to the Pacific Ocean, and the Rio Hondo flows southwestward to the Los Angeles River. Santa Fe Dam and Reservoir was constructed under the authorization of the Flood Control Act of June 1936 (as amended). The project was incorporated into a comprehensive development plan described in the District Engineer's report titled, "Survey Report, Flood Control, Los Angeles and San Gabriel Rivers and their tributaries and Ballona Creek, California", dated 5 February 1940. This comprehensive plan was implemented by the Flood Control Act of 1941.

Santa Fe Dam is an essential element of the Los Angeles County Drainage Area (LACDA) flood control system. The primary purpose of the dam is to provide flood protection for the densely populated area between the dam and Whittier Narrows Reservoir. The flood control operation of Santa Fe Dam is also coordinated with the operation of other Corps dams in the LACDA system, namely Whittier Narrows Dam, Hansen Dam and Sepulveda Dam. Although it has no authorized storage allocation for water supply, its flood control operation provides incidental water conservation benefits to the people of San Gabriel Valley and other parts of the Los Angeles Basin.

Santa Fe Dam contains sixteen 6-foot wide by 9-foot high hydraulically operated slide gates. The combined maximum capacity of the sixteen outlets (with each gate wide open and the reservoir level at spillway crest elevation - 496 feet) is 41,000 cfs. During "stand-by" position, one gate is opened at 0.5 feet and the rest are in a closed position. This gate setting is designed to pass low flows and build a debris pool during high inflows. Discharge rates within the debris pool range allows the Los Angeles County Department of Public Works to divert the flow to its spreading facilities, thereby enhancing water conservation. Once the reservoir level reaches elevation 456 feet, flood control releases are initiated. The dam can release a maximum of 41,000 cfs. During recession, the flood pool is drained as rapidly as possible, consistent with the achievement of downstream flood control. This is done to empty the flood control pool in preparation for the next flood. As soon as the flood pool is drained, releases are reduced so that LACDPW can resume water conservation operation.

Santa Fe Dam's spillway structure is of an overflow concrete ogee type located in the right or northwestern abutment of the dam. The spillway has a crest length of 1,200 feet and a crest elevation of 496 feet. Immediately downstream of the overflow section of the spillway structure is a concrete lined stilling basin. The spillway channel is 1,200 feet wide and extends approximately 5,000 feet from the end of the stilling basin. During spillway flow, the gates are closed gradually to maintain the combination of the spillway flow and outlet works flow to 41,000 cfs.

The current water control manual for Santa Fe Dam was approved in October 1967. Revision of the manual is tentatively scheduled for 2003. The revision will take advantage of the improvements currently underway in the LACDA channels.