1928 Catastrophic St. Francis Dam Failure, Los Angeles County: Worst American Civil Engineering Failure of the 20th Century

At just before midnight on Monday, March 12, 1928, the towering St. Francis Dam in Los Angeles County broke apart and sent a massive wall of wind and water hurdling down the San Francisquito and Santa Clara valleys to the Pacific Ocean. More than five hours elapsed from the time the dam failed to when the roaring roiling water mass reached the ocean more than 50 miles away. Approximately 450 mostly sleeping people died as the wave scoured white the rugged valley terrain over which it passed.

The St. Francis Dam Failure is considered the greatest American civil engineering failure of the twentieth century. It was the second major calamity to strike California just 22 years after the 1906 San Francisco earthquake. Yet, unlike the San Francisco earthquake, remarkably few people are aware of the story of the St. Francis Dam and its place in Southern California’s water system and history.  

The man responsible for building the St. Francis Dam was the visionary engineer, public servant, and American entrepreneur William Mulholland (1855-1935). He accepted full responsibility for errors in dam construction that led to its demise and the death of hundreds of people living in the San Francisquito and Santa Clara valleys. The St. Francis Dam was the 19th dam he had built. He died some 7 years after the catastrophe at age 79, crushed. His children were “stunned into silence by the tragedy, as if even to speak of it was too painful to endure.” (1) But his granddaughter, Catherine, has written well about the disaster, which occurred when she was five-years-old. (2-3) Her father Perry, Williams’ son, accompanied him to the dam site on March 13, 1928 to survey the awful damage. Two other excellent books about the story of St. Francis Dam are available from the Historical Society of Southern California. (4-5)

William Mulholland: Architect of the Los Angeles Water Supply System

William Mulholland designed and built the St. Francis Dam as a late element of the sprawling Los Angeles’ water supply system, which was also his creation. It would be a terrible mistake to remember this visionary only for the St. Francis Dam disaster near the end of his life, as he almost single-handedly forged the Owens Valley-Los Angeles Aqueduct [henceforth, Aqueduct] that saved Los Angeles County from an otherwise dead-end fate as a semi-arid plain hugging the Pacific Ocean.   

Mulholland was born in Belfast, Ireland in 1855, but grew up in Dublin, Ireland. At age 15, he immigrated with his brother to New York as a journeyman sailor in 1874 at age 19. He made his way to Los Angeles, arriving there in 1878 at age 23, along with a steady influx of European settlers who traveled to California upon its joining the United States in 1848. Mulholland’s first job in Los Angeles County was as a “zanjero”, or water ditch tender, who looked after unlined uncovered water ditches known “zanjas” for the Los Angeles City Water Company, which was one of several private providers of water to the people of Los Angeles. (6)

When drilling water wells into the aquifers of the Los Angeles basin, Mulholland struck a buried tree trunk at a depth of 600 feet! (7) This was the stimulus for his lifelong interest in physical geology, which was in its infancy, and his compulsion to become an engineer through prodigious reading and working alongside some of the best water resource engineers of his era. He rose through the ranks of the Los Angeles City Water Company where he was known for his strong work ethic and appetite for working under difficult conditions. His fantastical memory for every piece of pipe, gate valve, and fire hydrant laid in the ground in Los Angeles between 1878 and 1902 led to his appointment as manager of the Los Angeles Bureau of Water Works and Supply (BWWS), which supplanted the Los Angeles City Water Company when it passed into the public sector in 1902. He was 47 years old.

Mulholland refused even to consider running for elected office, although he was deeply immersed in punishing politics most of his life through the various public works projects he commandeered. He enjoyed remuneration for his good works, e.g., at the zenith of his career he was the highest paid public official in California. (8) He also surrounded himself with young engineers who were largely self-educated and willing to tackle extremely difficult projects such as the Aqueduct. One in particular was his best friend and colleague Harvey Van Norman. It was Van Norman who accompanied Mulholland to the remains of the St. Francis Dam on the morning of March 13, 1928.

Mulholland’s best friend before Van Norman was Fred Eaton (1836-1934), who was mayor of Los Angeles from 1898 to 1900. Mulholland broke off the friendship with Eaton when Eaton speculated in land relating to the building of the Aqueduct. Eaton was not the only Los Angeles businessman to speculate in real estate in this way. Civil war soldier Harrison Gray Otis (1837-1917) and his son-in-law, Harry Chandler (1864-1944), owner and publisher, respectively, of the Los Angeles Times newspaper, EH Harriman, president of the Southern Pacific railroad, and Moses Sherman, a real estate developer and member of the city’s Water Board, “engaged in shadowy dealings and traded on inside information, learning ahead of the public (probably from Sherman) where the aqueduct would terminate, and where excess water would be stored in the water table under the San Fernando Valley, adjacent to Los Angeles. All told, Otis and his colleagues bought 16,000 acres of this valley, which they later sold at a handsome profit.” (9) The investment group is known as the San Fernando Syndicate. Mulholland would have nothing to do with these men.

Water Crisis Develops in Los Angeles

Los Angeles basin struggles with its semi-arid Mediterranean-type climate: the basin is very dry and sometimes droughty except when it is deluged with horrendous rainstorms that unleash furious floods down mountain washes that turn the basin temporarily into a muddy shallow lake. (10) Between 1902 and 1905, Mulholland rebuilt the city’s outmoded water distribution network, cutting the water rates for domestic service in half, and turning a profit for the municipality of $640,000. (11) Drought conditions came in 1904 when winter storms did not produce much rain. Mulholland joined forces with Eaton who in 1892 had already scouted the Owens Valley some 210 miles to the northeast as a potential alternative source of water.

The idea was to collect water washing down the steep Eastern slope of the Sierra Nevadas as part of the Owens Valley watershed and transport it across the Mohave Desert and San Gabriel Mountains to Los Angeles via an aqueduct. Engineers planned to use gravity to move the water down the aqueduct: Owens Valley was at an elevation of 3,560 feet, compared with Los Angeles’ elevation of 300 feet. “With  233 miles of run (from an intake 12 miles north of Independence near elevation 3,900), an hydraulic grade of over 15 feet per mile was thereby realized, far above what anyone else had ever had to work with in the famous New York aqueducts. This surplus in theoretical hydraulic energy head meant that [inverted] siphons and pressure tunnels should be able to traverse even the most difficult terrain,” explains historian J. David Rogers. (12)

After Eaton in 1904 showed Mulholland the rugged Owens Valley “by mule team, a buckboard, and a demijohn of whiskey”, Mulholland became convinced that an aqueduct from this valley would solve the water crisis developing in the burgeoning metropolis of Los Angeles (population of 390,000 and growing in 1905). Mulholland persuaded the Board of Water Commissioners to finance engineering studies to get the ball rolling. An aqueduct of 250 miles was unprecedented at the time: the longest Roman aqueduct at Marcia is 58.4 miles in length and the new Croton Aqueduct in New York, consturcted between 1885 and 1893 was 45 miles from end to end. (13)

An army of about 5,000 men used dynamite, railway-mounted steam shovels, dredging machines and mules to dig out 233 miles of canals and tunnels. They carved the Aqueduct out of barren hot terrain, laying pipe across searing stretches of desert and going over, and often through, solid Sierra Nevada granitic rock. The pathway selected by Mulholland followed California’s system of earthquake faults. Indeed in 1872, a Richter Magnitude 7.8 earthquake lifted the Sierras towering above Owens Valley some 23 feet. The Aqueduct is always vulnerable to rupture by another earthquake, which could result in an abrupt cessation of water flow to Los Angeles, at least for as long as it might take to repair the Aqueduct. This fact is another reason why Mulholland wanted to build St. Francis Dam in the foothills above Santa Clara Valley facing the Pacific Ocean—that is, to sequester enough water to slake the thirst of Angelinos until a ruptured Aqueduct could be repaired.

The Aqueduct opened on November 5, 1913. Two powerhouses (No. 1 and No. 2) were built at its lower end to produce hydroelectric power using the sudden drops in elevation to catapult the water steeply downward and forward to turn the giant turbines. Power house No.2 was situated below the St. Francis Dam built 12 years later, and would be demolished when the dam failed on March 12, 1928.

The Violent Water Wars

Many ranchers and landowners in the Owens Valley watched their land dry up and lose value as the water to which they were accustomed flowed to Los Angeles. They were furious and organized into a group known as the Owens Valley Property Owners, led by the chief bankers and businessmen of the Valley, two brothers named Mark Quayle Watterson and Wilfred W. Watterson. In May 1924, the first of many dynamitings of the Aqueduct occurred on an open section two miles north of the small town of Lone Pine in the Owens Valley. In November 1924, 100 ranchers commandeered the head gate of the Aqueduct in the so-called Alabama Hills, spilling the water into the surrounding desert. Renewed violence occurred in May 1926 when ranchers blasted a aten-foot section of concrete-lined pipe one mile south of the Alabama Hills head gate.

In April 1927, “a bitter fight in Sacramento resulted in the State Asesembly’s condemnation of what it called Los Angeles’ ‘ruthless devations’ of the Owens Valley. It demanded reparations for land damage to Owens Valley ranchers by the Loas Angeles Water Board, but the Senate tabled the resolution, which produced a renewed fury in Owens Valley.” (14) When the City of Los Angeles refused the demand for reparations (the Watterson produced one invoice for $5.3 million), the ranchers resumed dynamiting the Aqueduct. On May 27, 1927, they dynamited “No Name Sipon and 475 feet of the Aqueduct. On May 28, 1927, they dynamited the penstock (intake structure) of the Big Pine powerhouse. (9,14)

As lawlessness was sharply increasing in the Owens Valley and the City of Los Angeles was in danger of losing both its water and power supplies, a train filled with Los Angeles detectives armed with Winchester carbines sped to the Owens Valley to guard the Aqueduct. A reward of $10,000 was offered for information leading to the arrest of the dynamiters. Mulholland and Van Norman went there, too, to view the damage, and were outraged. The detectives placed Owens Valley under martial law (although they had no legal basis to do so, according to one observer), but this failed to stop the dynamiting, which continued for two more months. (9) It was great pleasure, therefore, that Mulholland could reassure the city that the completion of the San Francis Dam would provide enough capacity to avoid serious power and water shortages to the city. Indeed, one of the reasons Mulholland built the St. Francis Dam was in response to the so-called “Water Wars” between Owens Valley ranchers and the City of Los Angeles.

The Water Wars finally came to end when the Wattersons were convicted of embezzlement and fraud in their banking enterprise. The damage to the Aqueduct totaled about $250,000; this amount did not include loss of water and power to the City of Los Angeles. Nevertheless, these costs “paled beside the emotional and financial losses in Owens Valley as it grew clear that Los Angeles had once more prevailed and loomed as a permanent overlord.” (15)

Construction of St. Francis Dam

Mulholland realized after completion of the Aqueduct that existing reservoirs built along the line could not meet the shortfalls of a multi-year drought in Los Angeles. As a result, he conspired to build a second generation of 8 reservoirs closer to Los Angeles and south of the San Andreas fault (no one in the early 20th century had any idea about the system of faults that characterize Southern California) (for list of reservoirs, please see Nunis, p. 20). The biggest dam was to be constructed “along the San Francisquito Creek, adjacent to the San Francisquito Canyon Construction Camp, which had been built within a broad alluvial flat located about halfway up the canyon to house the men working on the 6 and ¼ miles of tunnels along San Francisquito Canyon (between what later became the two powerhouses), explains Rogers. (16) By

Mulholland was drawn to this particular site because of a natural narrowing of the canyon downstream from the broad alluvial flat that he thought would form a perfect floor for the massive reservoir. “Unbeknownst to Mulholland,” writes Rogers, “the reasons for the favorable topography of the dam site lay in the fact that this portion of the canyon had already served as a natural reservoir due to damming of San Francisquito Creek by large prehistoric landslides developed within the Pelona Schist along the southeastern canyon wall. The seemingly-intact Pelona Schist [name of a rock type] had actually rotated downward onto the opposing bank of Sespe conglomerate [another rock type], thereby blocking the canyon and creating a large landslide dam. The waters of San Francisquito Creek had eventually overtopped the landslide dam and re-excavated the channel. The broad flat area, seen by Mulholland as an excellent reservoir site, had actually been created through sedimentation behind the paleo-megalandslide dam.” (17)  This was all very easy to see after the dam ruptured and the walls of the canyon were bared for all to see. But Mulholland had also carefully performed exploratory “adits” or horizontal tunnels into the sides of the narrowing, so it is difficult to understand why he too didn’t diagnose the surficial geology of the narrowing.

Preliminary studies of the main St. Francis dam structure were completed in May 1923, on year before the Owens Valley ranchers first dynamited the Aqueduct. Los Angeles filed a condemnation petition for the proposed reservoir inundation area with the federal government in April 1924 just as they began construction, according to Rogers. In January 1925 the city finally notified via public notice that it was building a dam and reservoir in the San Francisquito Canyon, which riled the ranchers and orchard growers downstream who were dependent on the perennial flow of the Santa Clara River. The rationale given to the ranchers and growers was that “the sole intent of the dam was to entrain an ‘emergency supply’ of water, to be derived solely from” the Aqueduct, and would not touch the perennial flow of the San Francisquito Creek that would presumably continue at its usual rate below the dam. (18) This was not exactly true because Mulholland was including the Creek’s flow in the calculations for the reservoir’s storage capacity.

The St. Francis Dam was made of concrete in a step-wise pattern. Its height was raised 20 vertical feet (11% of its original 175 foot height) without any substantive widening of the dam’s base width. This was a no-no that was discovered after the disaster. The dam was completed in May 1926. There were also no measures to reduce seepage forces underneath the dam, which were determined to be the root cause of the dam’s failure. Measures to reduce seepage might have included “a deep cutoff wall/trench, a grout curtain to inhibit underdam seepage, and uplift pressure relief wells throughout the dam.” (19) In fact, 8 uplift pressure relief wells HAD been placed under the main dam block, which HAD survived the disaster.

It is unfair to judge Mulholland by technological advances discovered only as a result of his dam’s failure. Many engineers, for example, were just beginning to appreciate the destabilizing effects of uplift pressures in the late 1920s, when the dam failed. Rogers explains that “in lay terms, uplift pressures are caused by bouyance due to simple submergence or percolation. When water fills behind a dam, the dry dead weight of the dam is significantly reduce because of the water pressures within the foundation rock beneath the dam are pushing upward. Estimating the amount of this upward lifting is critical to dam stability assessments, as each pound of uplift pressure negates a pound of the dam’s seemingly immense dead weight. (19)

Dam Failure

Water from the Aqueduct was first diverted to the St. Francis reservoir on March 1, 1926, several months before completion. It filled up rapidly, especially after the city filed an amended application to the California Division of Water Rights specifically requesting appropriation of the canyon’s ‘flood and surplus water.’ The outflow along San Francisquito Creek immediately ceased.” (20) The ranchers’ well levels began to lower and they demanded redress. An experiment was performed that confirmed that the river gravels were no longer recharging because of the reservoir, but the legal maelstrom that ensued was not straightened out when the dam burst 9 months later.

Cracks in the dam began to appear following the initial filling of the reservoir in 1926-1927, which Mulholland attributed to the curing of the concrete. These were infilled with hemp and sealed with wedges of oakum and then back-filled with cement grout to seal off active seepage, which was another no-no. The reservoir in February 1928 was filled a second time to the dam’s crest and new seepages developed in the foundation within the Sepse conglomerate. When the level reached to within 3 inches of the spillway slits, the water from the Aqueduct was turned off. The previous year’s leaks gushed forth and new leaks developed. Mulholland ordered installation of an 8-inch-diameter concrete pipe underdrain along what was called the wing dike of the dam.

On Monday, March 12, 1928, winds were blowing water over the top of the dam, which made discerning leaks very difficult. Concerned about the level of water behind the dam, which wasn’t looking too good, water was released in the San Francisquito Canyon for the first time in 2 years. The ranchers did not have time to rejoice that their well levels were rising, and were actually were concerned that water was flowing in the usually dry creekbed.  When another leak sprung in the dam, Mulholland was called and he and Van Norman sped to the dam, reaching it at 10:30 a.m. For 2 hours they inspected it carefully and declared it sound.

Four employees drove past the dam on their way to No. 1 powerhouse 5 miles above the dam within an hour of its failure. One noticed a 12-inch downdropping cutting across the road, which snaked along the eastern side of the canyon, contiguous with the dam’s eastern abutment built on the Pelona Schist bedrock. The idea behind this observation was that the east abutment landslide was beginning to drop and thrust against the dam’s left side (facing downstream). Another employee at about 11:50 p.m. on March 12, 1928, heard strange crashing sounds about a half mile along the length of the reservoir. He said during the coroner’s inquest that he pulled over to smoke a cigarette, but kept the engine running on his motorcycle. He then continued to No. 1 powerhouse, having narrowly missed annihilation. A third employee at No. 1 powerhouse spoke by phone to the damkeeper at No. 2 powerhouse at 11:57 p.m., who reported that everything was normal.

Liquid Avalanche

The lights of Los Angeles 50 miles from the St. France Dam flickered momentarily at 11:57 and ½ minutes p.m. on March 12, 1928. The Bureau of Power and Light operators at Receiving Stations “A” and “B” inside Los Angeles city limits noted at the same time a sharp drop in voltage for two seconds. Saugus substation (Southern California Edison Company) shorted out its 60,000 volt line to Lancaster, California, at around 11:57 p.m. Thus the 11:57 and ½ minutes has been considered a good estimate of when the dam began to break apart. (21) The various times that abnormalities were noted by operators of electrical stations throughout the area provided timing for the event.

Careful studies after the fact determined that the water behind the dam took five minutes to travel the mile and one half to Powerhouse No. 2 located below the dam. The height of the wall of water for the first few miles was 100 to 140 feet, and huge pieces of the dam, some weighing ten thousand tons, were washed one-half mile or more down the canyon. (21) These chunks of dam were later blown up by authorities supposedly to dissuade sightseerers. The rubble of the chunks is still there.

When the two 110,000 lines of the Bureau of Power and Light of the Los Angeles Department Water and Power failed for those two seconds (see above), Edison picked up the lines by utilizing its Big Creek lines; and life in Los Angeles returned to normal. However at 12:39 and ½ minutes a.m. the first of these 220,000 lines from Big Creek shorted out and was followed a minute and ½ later by the second. Outland explains that “[t]o make the outage complete, at 12:45 a.m. the Saugus substation of Edison, which was not directly connected with the Big Creek lines, although they passed close by, shorted out and gave to most of Ventura County and the city of Santa Barbara the first indications of trouble. Thus metropolitan Los Angeles, most of the two northern counties, and the Antelope Valley region were without electricity…” (22)

The flood moved down the San Francisquito valley and then into the Santa Clara valley at speeds that varied between 18 mph and 6 mph. The 38,168 acre feet of water in the 600 acre St. Francis Reservoir took 5 hours and 27.5 minutes to reach the Pacific Ocean 53.8 miles away. The average velocity calculated to 9.8 mph. (23) When the water neared the ocean it was “50% water, 25% mud, and 25% miscellaneous trash,” according to one observer. (24)

Survivors spoke about the sound of the oncoming flood and its riverine flood smell. Most of the corpses and some of the survivors found clinging to trees were naked, which is similar to the condition of the corpses in the path of the 1963 Italian Vajont reservoir overturning, as described elsewhere. (25) Italian experts attributed the condition of the corpses to the roaring wind that had a force or pressure two times the bombs dropped on Hiroshima. The pressure wave of the wind blew off people’s clothes and even their skin and shocked their internal organs. One survivor of the St. Francis Dam catastrophe remarked that the 50 people in Santa Paula who had died “were not drowned—but battered and bruized [sic]—but don’t show anguish—so probably they were taken in their sleep and didn’t know what had happened.” (26)

Why the St. Francis Dam Failed

Investigations of why the dam failed focused on the buried paleo-landslide on which the east abutment was built. Rogers explains that “[i]f the failure sequence were initiated by massive sliding of the east abutment, arch stresses thrusting towards the east abutment would have been truncated, and thereby dramatically increasing the cantilever loads on the dam’s main section…With arching capacity lost, a sudden and dangerous overstressing of the dam’s cantilever load capacity would have occurred, leading to excessive tilt and overturn….The tilt would have become progressively worse until some major component of the structure actually collapsed, setting about a rapid chain of events.” (27)

Summary

The St. Francis Dam was constructed as an emergency supply of water for the city of Los Angeles in case of interruption of the Los Angeles-Owens Valley Aqueduct during times of extended drought either by earthquakes or by sabotage. The dam not only provided an emergency source of water, but also electricity to several counties. Physical geology was in its infancy when the dam was built. Even though Mulholland performed testing of the surficial geology appropriate to the times, he somehow missed the paleo-landside aspect of the narrowing in the San Francisquito valley. Maybe he didn’t drill deep enough or enough times to locate important variations in the geology underlying the dam’s foundation and abutments. Yesterday’s solutions can become today’s disasters.

Sources:

1. Catherine Mulholland: “William Mulholland and the St. Francis Dam”. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p. 111.

2. Catherine Mulholland: “William Mulholland and the St. Francis Dam”. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; pp. 111-138.

3. Catherine Mulholland: “William Mulholland and the Rise of Los Angeles”. University of California Press, 2002.

4. Charles Outland: “Man-Made Disaster: The Story of St. Francis Dam”. Original copyright 1963, The Arthur H. Clark Company, current edition published by Historical Society of Southern California, 2002, 275 pages, with fold-out map.

5. Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002, 182 pages, with many previously unpublished photos.

6. Ibid, p. 3.

7. For more on the geology of the Los Angeles basin, please see: SEMP Biot #365: “Infamous New Year’s Day Flood, Los Angeles Basin, 1934” (May 28, 2006) at: http://www.semp.us/biots/biot_365.html and SEMP Biot #369: “Los Angeles Basin's 1938 Catastrophic Flood Event” (June 7, 2006) at: http://www.semp.us/biots/biot_369.html; accessed June 24, 2006.

8. J. David Rogers: “A Man, A Dam and a Disaster: Mulholland and the St. Francis Dam. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p 5. 

9. Mark Wheeler: “California Scheming” in “Smithsonian”, vol.33, no.7, October ’02. Available online at: http://www.mindfully.org/Water/Owens-Lake-WaterOct02.htm; accessed June 24, 2006.

10. Mike Davis: “Ecology of Fear: Los Angeles and the Imagination of Disaster”. Metropolitan Books, 1998, pp. 10-20.

11. J. David Rogers: “A Man, A Dam and a Disaster: Mulholland and the St. Francis Dam. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p 6. 

12. Ibid, p. 8.

13. Ibid, p. 10.

14. Catherine Mulholland: “William Mulholland and the St. Francis Dam”. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; pp. 114-115.

15. Ibid, p. 118. Catherine Mulholland footnotes the Los Angeles “Examiner”, February 22, 1928.

16. J. David Rogers: “A Man, A Dam and a Disaster: Mulholland and the St. Francis Dam. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p 16. 

17. Ibid, p. 22.

18. Ibid, p. 27.

19. Ibid, p. 30.

20. Ibid, p. 32.

21. Charles Outland: “Man-Made Disaster: The Story of St. Francis Dam”. Original copyright 1963, The Arthur H. Clark Company, current edition published by Historical Society of Southern California, 2002, p. 82.

22. Ibid, p. 96.

23. Ibid, pp. 249-250.

24. Ibid, p. 148.

25. SEMP Biot #373: “Epic Vajont Dam Disaster, Italy, 1963: Manmade or Natural?” (June 17, 2006) at: http://www.semp.us/biots/biot_373.html; accessed June 25, 2006.

26. Catherine Mulholland: “William Mulholland and the St. Francis Dam”. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p. 129.

27. J. David Rogers: “A Man, A Dam and a Disaster: Mulholland and the St. Francis Dam. In Doyce B. Nunis, Jr. (Ed.): “The Saint Francis Dam Disaster Revisited”, Historical Society of Southern California, 2002; p. 66.