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Construction of the St. Francis Dam was completed in May 1926. The final structure

contained 137,000 cubic yards of concrete, stood approximately 200 feet high, and arched

upstream on a 492-foot radius (Geiger 1928:520). Outflow of the San Francisquito Creek

ceased as the St. Francis reservoir filled at a rate “nothing short of dramatic by modern

standards, the level rising at an average of 1.8 feet per day over the first three months”

(Rogers 1995:32). Members of the Santa Clara River Protective Association responded by

instructing Attorney C.E. Grunsky to resolve the dispute as necessary. California’s Chief of

Water Rights, Edward L. Hyatt, called for field tests to be performed to settle the dispute,

which resulted in affirmations of the protective agency’s complaints, through the matter still

was unresolved at the time of the failure (Rogers 1995:33).

Various aspects of the dam’s design have been judged problematic by recent scholars.

Twice during construction, BWWS engineers added capacity to the reservoir by increasing

the dam’s height; they also added a concrete wing-dike 1,300 feet past the dam’s west

abutment. This created a “dangerous situation,” as the strength of a gravity dam is dependent

on a prescribed width/height ratio (Rogers 2006:16). This, and other design oversights,

including the absence of drainage galleries needed for inspection purposes, contraction joints

to control cracking, and cut-off walls or a grout curtain to control seepage and prevent uplift

all resulted in the dam being a “less than conservative” design (Petroski 2003:116).

Cracks began to appear in the dam during the initial filling; Mulholland referred to

these fractures, which were widest at the base and narrowed upwards, as “transverse

contraction cracks” (Rogers 1995:35). In 1927 these cracks were filled with hemp, sealed

with oakum, and back covered with cement grout (Rogers 1995:33, 35). In early 1928, when

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