The entry says that half a dozen inquiries were sitting within the week. This piece goes through them in the order they reported, as Engineering News-Record abstracted them in the spring of 1928 and as the first of them printed its own report. Six bodies looked at the same canyon. Five found the same cause in the same rock. The sixth looked at the other side.

Engineering News-Record listed their members on 5 April. Governor C. C. Young’s commission: A. J. Wiley of Boise, chairman; F. E. Bonner of the Forest Service; F. H. Fowler; H. T. Cory; and two geologists, George D. Louderback of Berkeley and F. L. Ransome of Caltech. The Los Angeles County district attorney’s: Edward L. Mayberry, chairman, C. T. Leeds and Walter Gordon Clark, engineers, and Allen E. Sedgwick and Louis Z. Johnson, geologists. The city council’s: Elwood Mead, the federal Commissioner of Reclamation, chairman, with Louis C. Hill and Lansing H. Beach, and D. C. Henny advising. The Bureau of Water Works and Supply’s own: three geologists, D. W. Murphy, Robert T. Hill and C. F. Tolman of Stanford. The Ventura County supervisors’: C. E. and E. L. Grunsky, with a geologist to be chosen. And the coroner’s jury, nine men, six of them engineers or contractors. “The preponderance of engineers, contractors and geologists,” the journal said, “is noteworthy.”

The Governor’s commission, 24 March

The Governor’s commission met in Los Angeles on the morning of 19 March, a week after the failure, and was given its instructions by the Director of Public Works, Bert B. Meek: “We must learn, if it is possible, just what caused the failure of the St. Francis Dam; the lesson that it teaches must be incorporated into the construction of future dams. There must be no repetition of this catastrophe if it is humanly possible to prevent it.” It went to the canyon, took its own surveys with the state highway force, had rock and concrete tested, was furnished by Mulholland with the bureau’s plans and photographs, and signed its report on 24 March. It was printed by the state, with thirty plates, and published on 20 April.

It is the report the later ones were measured against, and the entry draws on it throughout. Its description of the dam, from the bureau’s drawings, gave the dimensions that every later writer used, among them a maximum section “205 feet high and 175 feet thick at the base”. Its account of the construction set out what had not been done: the east wing “notched into the rock of the canyon wall and carried up the natural inclined plane of the rock in the abutment, without steps, and with no cut-off wall”; on the west a trench “about 3 feet wide and 3 feet deep” dug “as deep as it could be carried by use of picks, and finished by prying out rock with gads”; drainage “only in the center”; “No inspection gallery was carried through the dam, nor was any pressure grouting attempted under any part of the structure.” Its geology, by Louderback and Ransome, described the schist that “would slip like a pack of cards thrown upon a table” and the conglomerate that, placed in water, underwent “a startling change”.

Its conclusions were three: that “the failure of St. Francis Dam was due to defective foundations”; that there was nothing in it “to indicate that the accepted theory of gravity dam design is in error”; and that it “indicates the desirability of having all such structures erected and maintained under the supervision and control of state authorities”. It thought the west end had gone first, “near or at the old fault or contact between the conglomerate and schist”, by “either a blowout under, or a settling of the concrete at this place, or both”, and that the rush of water had then scoured the schist from under the east end. Of the landslides on the east it was definite: “all of the recent landslides in the vicinity of the dam site took place after and as a result of the failure of the dam and were in no way responsible for such failure.” And it read the chart of the water-stage register on the standing section as the record of water leaving the reservoir, “starting about 11.30 p.m. (corrected time)”, while warning that “too much reliance must not be placed upon this”, since the time scale was small and “the accuracy of the clock movement is not certain”.

The city council’s board, 31 March

Mead’s board submitted its report on 31 March; its signatures included R. F. Walter, chief engineer of the Bureau of Reclamation. It agreed that the type and dimensions of the dam and the quality of the concrete were adequate, that no earthquake had caused the failure, and that the foundations had. Its contribution was to put the rock in numbers and to say why clear water could be dangerous. The schist, it found, was “so thoroughly fractured that in many places it is actually split or can readily be split into thin pieces as thin as or thinner than slate”, with “slippery sliding surfaces with small adherence, extremely favorable to the formation of large slides when undercut”; six samples crushed at 3,600 to 11,000 pounds to the square inch, and soaking did not weaken them. The conglomerate, “when wet it disintegrates rapidly to a slippery, friable mass or even loses all shape in a few minutes. A piece immersed in water gives out bubbles of air practically until the time of collapse.” Three samples tested dry broke at 600 to 1,900 pounds; two soaked for ten minutes broke at 210 and 845; two soaked for twenty-four hours “disintegrated into fine particles and sand grains and therefore could not be tested”; and a large number of others taken from the west hillside “all disintegrated within a few hours”.

Then the mechanism. The cementing material of the conglomerate was clay, iron oxides and silica; the fissures were filled with gypsum, “slowly soluble”. “If the water passing through these fissures carried with it gypsum in solution, the water would remain clear and would carry no evidence that it was washing away part of the foundation of the dam.” The board recorded that the inspection by Mulholland and Van Norman on 12 March “disclosed nothing abnormal or that would cause apprehension”, that “Mr. Mulholland was positive that all seepage streams were clear where they emerged below the dam”, and that the seepage had increased “from 7.6 miner’s inches (0.16 sec.-ft.) on Feb. 29 to an estimated quantity of 50 miner’s inches (1 sec.-ft.) on March 12”. It thought the first leak had begun under the part of the dam standing on the conglomerate, that the water had run across to the east bank and undermined it, and that it was a slide of that bank, “and not the breaking of the dam itself”, that had first broken the Edison line. From the register’s chart it drew a table of the outflow, rising from a few hundred second-feet at midnight to 600,000 or more at ten to one.

The district attorney’s board, 4 April

Mayberry’s board reported to the district attorney, Asa Keyes, on 4 April, with “an exhaustive review of the geology of the site” and its own laboratory tests. It found the design “in accord with accepted practices” and the concrete satisfactory, found no evidence “that the destruction of the dam was or might have been caused by an explosion, either accidental or intentional”, and ascribed the failure “to defective foundation materials, some of which, while reasonably hard when dry, became soft and yielding when saturated with water”. The conglomerate, it wrote, “became softened by absorption and percolation of water from the reservoir and was by hydrostatic pressure pushed out from under the dam structure, permitting a current of water at high velocity to pass under this sector of the dam”. Along the fault “the first foot or two of the conglomerate at the contact shows a decided flow structure”, a shear zone along which water had moved; under the buttress of the wing dam the rock “is so disintegrated that it has nearly lost its original character and is so soft that it can be excavated easily with a prospector’s pick and in some places by hand”.

It read the register’s chart differently from the Governor’s commission: the slow fall of the pen through 12 March, with nothing drawn off, it took as water already leaving the reservoir, 12.9 second-feet over the day and 74 in the last three and a half hours. “The movement of the gage after 11:30 is so rapid that it cannot be accepted as an indication of the water level in the lake, but merely as an indication of the water level at the face of the dam.” On the evening of the failure “a large leak developed, probably not far from the westerly abutment that remains standing, and undermined the dam for a length of 120 ft. or more”, and the dam over it sheared off, “probably at a shrinkage crack”, leaving two cantilevers that “failed progressively in sections”.

Its conclusion went one step past the others: “that the dam as designed should not have been constructed at this location, and that due to local conditions it is not economically feasible to erect a safe dam at this location.” It recommended a state permit for every dam, and a board of engineers and geologists appointed by the Governor to pass on the design, foundation and construction of all of them.

The water board’s geologists

Hill, Tolman and Murphy reported to the Board of Water and Power Commissioners that had hired them; only a summary was released. “The manner in which the dam failed or where the first break occurred has not been determined.” “There were weaknesses in the foundation under both the eastern (left) and the western (right) abutments sufficient to have caused failure.” On the east it was the planes of the schist, lying in the direction of the slope, which “especially when wet, would permit easy sliding under the abutment”. On the west it was the conglomerate, cemented with clay that softened when wet and “cut by numerous fissures filled with gypsum. This gypsum is slowly soluble in water and any passage of water under the dam, even in small amounts, would in time produce openings.” And one observation that nobody else had made: “Recent surveys show a small movement at two points on the right bank (west side) since the dam was constructed.” It was the water board’s own geologists, in other words, who first wrote down that the ground on both sides was at fault, and that the west bank had moved.

The coroner’s jury, 12 April

The jury had sat through all of this; being the last to report, it “had read into its testimony findings of the four others”. Its verdict of 12 April is the one that has been quoted since. “The St. Francis Dam was defective due to the very poor quality of the underlying rock structure upon which it was built and to the fact that the design of the dam was not suited to inferior foundation conditions.” Building it “without having the design and foundation conditions passed upon by independent engineers and geologists” involved two errors, one of engineering judgment, which rested “upon the Bureau of Water Works and Supply and the Chief Engineer thereof”, and one of public policy, which belonged “to those to whom the Chief Engineer is subservient, including the Department of Water and Power Commissioners, the legislative bodies of city and state, and to the public at large”. The policy error was “the more fundamental”, and then the sentence: “A sound policy of public safety and business and engineering judgment demands that the construction and operation of a great dam should never be left to the sole judgment of one man, no matter how eminent, without check by independent expert authority, for no one is free from error, and checking by independent experts will eliminate the effect of human error and insure safety.”

It listed ten defects, from the fault contact under the dam and the two rocks on either side of it to the missing cut-off walls, grouting, inspection tunnels and side drains, and it found the exploration before the decision to build “entirely inadequate” and the inspection during construction “very limited and defective in principle owing to the fact that the inspections were made by the same people who were directing or doing the work”. On the leaks it was exact: the leakage “was remarkably small, considering the critical condition existing under the dam, and less than is commonly present in dams that are considered safe and have stood for years”; the chief engineer and his assistant had gone up about twelve hours before the end “and found that the water was coming out clear but picking up surface soil”; and had they concluded the dam was in danger, “the only safety measure possible at that time would have been to warn everyone in the possible path of the flood to move out”. It found no criminal act and recommended no prosecution.

The sixth report, June

The report for the Santa Clara Water Conservancy District, by C. E. and E. L. Grunsky with the Stanford geologist Bailey Willis, came out at the beginning of June, and Engineering News-Record headed its abstract “Sixth Report on St. Francis Dam Offers New Theories”. For the first time a report put weight on two diagonal cracks through the dam, one near each end, running down from the crest at about forty-five degrees, which the district’s engineer, V. M. Freeman, had seen as early as January. These, the Grunskys argued, were not shrinkage cracks but the marks of a vertical movement of the dam’s ends months before the failure.

Willis supplied the movement: the east abutment “was located on a landslide”, which the entry quotes. Water had reached the fault planes behind the lower part of the abutment; it had slid out by its own weight; the east wing, “left in the air”, had tilted the whole concrete structure towards the east; and the west wing “was swept out by the water rushing beneath as it was raised by the tilting”. The proof was a ladder from the upstream face that had been found crushed in a crack at the base of the standing section: the crack had opened wide enough to take the ladder in sideways, and “the later closing of the crack as the standing section settled back to place crushed the side of the ladder that was in the crack in a manner that proves that it could not have been crowded into the crack as it now exists”. Their conclusions: the site “was not a suitable site for a dam of the type that was there erected”; rigid dams should not be chosen “for localities where minor earth movements such as slides or swelling ground are probable”; the cracks of January “indicated a movement of the dam. Apparently the significance of these cracks was overlooked.”

The Governor’s commission had looked at the east bank and said the slides there came after the failure. Willis said one of them came before it and caused it. Nobody reconciled the two in 1928. Sixty years later, going back to the hillside with the inquest transcript and the bureau’s photographs, J. David Rogers found the old landslide where Willis had put it, and found that the blocks of the dam that had travelled farthest down the canyon had come from the east side.

The two editorials

Engineering News-Record drew its own conclusions in two editorials in the issue of 10 May that carried the four later reports. The first, “Muddy Seepage”, took the finding that the boards had all made and turned it into a rule, from the chemical analysis of the seepage that S. B. Morris of the Pasadena water department had made just after the break: the entry gives it. “This experience is a warning that clear seepage is not necessarily harmless; many minerals are soluble, and only a chemical test will show what clear water really contains.”

The second, “The Human Factor”, took the jury’s sentence and asked why the safeguards had been left out. “Incompetent foundation is the term that summarizes the findings of cause of the St. Francis dam failure. It is an apt term, yet it does not fully satisfy.” Two facts stood out: “entire disregard of the need of deep-set foundations, a cutoff wall, pressure grouting or any positive means of excluding water from the foundation as a whole”, and that the bureau’s engineering “always had been dominated by one man, the chief engineer, who took upon himself, in this case at least, entire responsibility, sought no independent opinions and adopted technical policies based on his unconfirmed judgment alone”. Had the work “been done by contract or under any other condition that would naturally have brought independent engineering opinion into the case, it is highly probable that some modified plan would have been substituted and the disaster avoided”. Nor could the responsibility pass to his assistants: “they cannot go farther than to report their views to their chief.”

What none of the six reports found was in the drawings the bureau had supplied. The maximum section the commission printed, 175 feet thick at the base, was not the section that had been poured; Rogers, measuring the construction photographs and the standing block in the 1990s, put the real base at about 148 feet, and found no record that the section borrowed from Hollywood had ever been recomputed when the dam was raised twenty feet. Every board took the bureau’s drawing as the dam. The entry’s list of what the record carries without argument begins there.

Sources

• Report of the Commission Appointed by Governor C. C. Young to Investigate the Causes Leading to the Failure of the St. Francis Dam near Saugus, California, California State Printing Office, Sacramento, 1928 (signed 24 March, published 20 April): the instructions, the description, the construction, the geology, the velocities, the register’s table, the conclusions. damfailures.org
• Engineering News-Record, 5 April 1928, pp. 553–555 (the commission’s report abstracted) and 561 (the boards’ and the jury’s members). archive.org
• Engineering News-Record, 19 April 1928, pp. 638–639: “All St. Francis Dam Reports Agree as to Reason for Failure”. archive.org
• Nathan A. Bowers, “St. Francis Dam Catastrophe—A Review Six Weeks After,” and “Reports of Four Boards of Engineers and Geologists,” Engineering News-Record, 10 May 1928, pp. 727–736, with Morris’s analysis and the editorials “Muddy Seepage” and “The Human Factor”: the water board’s geologists, the district attorney’s board, the coroner’s jury and the city council’s board, in the journal’s abstracts. archive.org
• “Sixth Report on St. Francis Dam Offers New Theories,” Engineering News-Record, 7 June 1928, pp. 895–896: the Grunskys and Willis. archive.org
• Verdict of Coroner’s Jury, Los Angeles, 12 April 1928, in the scan posted by SCVHistory.com. scvhistory.com
• J. David Rogers, “Who Designed the Ill-Fated St. Francis Dam?” World Environmental and Water Resources Congress 2017, pp. 379–393, for the base width and the landslide. Copyrighted; quoted briefly. scvhistory.com