Plaque
Sweetwater Dam, Spring Valley, California
Designed by James D. Schuyler and completed in 1888 to a height of
90 feet, this was once the tallest masonry arch dam in the United States,
and it served as a model for many others. The dam has survived three
overtoppings, and the water impounded by it has enabled economic
development of the National City, Chula Vista, and Bonita region.
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Sweetwater Dam, Spring Valley, California
When completed in 1888 to a height of 90 feet, Sweetwater Dam was once the tallest
masonry arch dam in the United States, and it led to many others of the same basic
design. The original construction began in November 1886 under the direction of Frank
E. Brown (civil engineer for Bear Valley Dam) with the rubble-masonry thin-arch design
being 50 feet in height. Subsequently, the owner of the water system called upon civil
engineer James D. Schuyler to continue and complete the project. Although the field of
hydrology was very new and not fully understood at the time, Mr. Schuyler determined
that the area of the watershed tributary to the dam, at about 186 square miles, justified
a higher structure that would increase the reservoir capacity by five times the original
design. He noted that the height change from 50 to 90 feet and the change to a gravity
arch design now relied on the arch design for its “factor of safety”, but felt confident with
the foundation and construction methods. There were subsequent modifications after
the dam’s original completion, which were completed under the direction of Schuyler
and civil engineer Hiram N. Savage. Since its original completion, Sweetwater Dam
has experienced unprecedented flood flows that overtopped the center crest three times
(1895, 1909, and 1916). Sweetwater Dam now stands 127 feet high with a crest length of
700 feet that provides over 27,000 acre-feet of water for domestic and irrigation use.
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H&H Database
Sweetwater Dam, Spring Valley, California
When completed in 1888 to a height of 90 feet, Sweetwater Dam was once the tallest
masonry arch dam in the United States, and it led to many others of the same basic
design. The original construction began in November 1886 under the direction of Frank
E. Brown (civil engineer for Bear Valley Dam) with the rubble-masonry thin-arch design
being 50 feet in height. Subsequently, the owner of the water system called upon civil
engineer James D. Schuyler to continue and complete the project. Although the field of
hydrology was very new and not fully understood at the time, Mr. Schuyler determined
that the area of the watershed tributary to the dam, at about 186 square miles, justified
a higher structure that would increase the reservoir capacity by five times the original
design. He noted that the height change from 50 to 90 feet and the change to a gravity
arch design now relied on the arch design for its “factor of safety”, but felt confident
with the foundation and construction methods. The volume of water expected to be
stored was 18,636 acre-feet. There were subsequent modifications after the dam’s
original completion, with the majority completed by 1940. The major modifications were
completed under the direction of Schuyler and civil engineer Hiram N. Savage.
Since its original completion, Sweetwater Dam has experienced unprecedented flood
flows that overtopped the center crest three times (1895, 1909, and 1916). The 1916
flood event measured the runoff at nine times the spillway capacity with depth of flow
nearly four feet over the center crest. During the 1916 flood event, damage did occur to
the side spillways, but the main dam was not damaged.
In 2005, after 117 years of service, this dam was still serving its original purpose of
storing water for domestic and irrigation use by the citizens of National City, Chula
Vista, and Bonita. Sweetwater Dam now stands 127 feet high with a crest length of
700 feet that provides over 27,000 acre-feet of storage for local and imported (via San
Diego County Water Authority) water. This is a one-year water supply for the entire
service area population of nearly 177,000 people. This dam is a testament to its gravity-
arch design, the construction materials and techniques of the era, and the design and
construction engineers who worked on it.
Additional information on Sweetwater Dam can be obtained from the following
references:
1. “The Construction of Sweetwater Dam”, by James D. Schuyler, ASCE Transactions
Vol. XIX, November 1888.
2. “Development of Dam Engineering in the United States”, Eric B. Kollgaard and
Wallace L. Chadwick, Editors; Chapter 3, by Jan A. Veltrop, for the Unites States
Committee of the International Commission on Large Dams, 1988.
These are photos of the historic hangar at North Island. 