This dam sits south of Silver Mountain and north of Glendora Ridge, which flank the deep San Gabriel Canyon. It is roughly upstream of the San Gabriel River's mouth at the Pacific Ocean, and downstream of the river's beginning at the confluence of its East and West Forks. Morris Reservoir is about long and above sea level at maximum pool, covering. The dam's crest itself is at an elevation of. Serving mainly flood control, flow regulation and groundwater recharge purposes, the slightly arched Art Deco-style gravity dam is high and long. Its spillway, located slightly north of the main structure, is a concrete-lined chute controlled by three steel drum gates. The reservoir created by the dam, when first put into use, was capable of storing. Due to sedimentation though since that time, its capacity has been reduced by about 29%. At present, the reservoir when filled holds approximately.
History
Morris Dam was originally slated to be called Pine Canyon Dam, but was renamed for the chief engineer of construction, Samuel Brooks Morris of the Pasadena Water Department. With the dam envisioned as a private structure for Pasadena, groundbreaking was in April 1932 and construction was completed in May 1934, four months behind schedule. Upon completion the dam was dedicated by former United StatesPresident Herbert Hoover. In 1935, contrary to its original purpose, Morris Dam was sold to the Metropolitan Water District of Southern California, which owned it through most of the 20th century. The dam was completed prior to the catastrophic Los Angeles Flood of 1938, the most severe flood recorded in Southern California since the Great Flood of 1862. Along with San Gabriel Dam, which at the time was under construction, the Cogswell Dam upstream and the Morris Dam greatly reduced the flood peak on the San Gabriel River, saving downstream cities millions of dollars' worth of damages. If it were not for the three dams, the flow past Azusa may have exceeded, but was limited to just, with Morris Dam alone reducing the flood peak by some.
Beginning in World War II, Morris Reservoir was used for the Morris Reservoir Naval Weapons Test Site for the U.S. Navy in conjunction with the California Institute of Technology. A wide variety of weapons, including torpedoes and ballistic missiles, had their trial runs here. Testing continued until the 1990s, when most of the structures at the associated military compound were demolished. However, the concrete foundations remain and are easily seen from State Route 39, which runs past the dam and reservoir. In 1995, MWD sold the dam to the Los Angeles County Department of Public Works, which continues to operate it and the reservoir today.
