One of the original five federal projects
authorized on March 13, 1903, under the Reclamation or Newlands
Act of 1902, Roosevelt Dam was the first major project to be
completed under the new federal reclamation program. This, the
world's highest masonry dam, was started in 1906 and completed
in 1911. The beginning of federal production of electric power
occurred at Roosevelt Dam when Congress, in 1906, authorized
the Reclamation Service to develop and sell hydroelectric power
at the Salt River Project.
The Reclamation Act of 1902 created the
United States Reclamation Service whose purpose was to design
and construct irrigation projects to aid the settlement of the
arid west. Previous efforts by individuals and private irrigation
companies were inadequate and often unsuccessful. With the creation
of the Reclamation Service, the lead role of the federal government
in developing large-scale irrigation projects was firmly established.
Roosevelt Dam, as originally conceived
and built, was to be a symbol of success and a showpiece for
the new agency. Service. Completed at a cost of 10 million dollars,
the primary function of the dam was to provide water storage
for the Salt River irrigation project and flood control for
the Salt River Valley. The dam contributed more than any other
dam in Arizona to the settlement of Central Arizona and to the
development of large-scale irrigation there. A secondary purpose
of the dam was to generate a moderate amount of hydroelectric
power. The lake created behind the dam, known as Lake Roosevelt,
contained more than a million acre-feet of water and was the
world's largest artificial lake.
plaques and a sign describing the benefits of the dam and
lake - water, electricity, and recreation.
National Historic Landmarks photograph.
As early as 1889, the narrow canyon below
the confluence of the Salt River and Tonto Creek had been identified
as a promising dam site by Maricopa County representatives who
wanted to convince federal legislators of the need for water
storage in the Salt River Valley. Despite the efforts of the
county, little federal interest in the Tonto Basin site was
shown until 1901 when the Geological Survey conducted studies
there in response to lobbying efforts by influential irrigation
advocates, Benjamin Fowler and George Maxwell. Leading the investigations
was Arthur Powell Davis, a nephew of John Wesley Powell who
would later become head of the Reclamation Service. Davis' report
was published in 1903 under the title "Water Storage on
the Salt River, Arizona." In this document, Davis provided
fairly complete plans for a dam and power facility at what later
became known as the Roosevelt site.
The formal submittal of Davis' report
to Charles Wolcott, Director of the Geological Survey in June
1902, coincided with the passage of the Reclamation Act of 1902.
Among the first five projects advocated for construction by
the Geological Survey and approved by Interior Secretary Ethen
A. Hitchcock was the Salt River Project. Final plans for construction
of the dam, published in the Third Annual Report of the Reclamation
Service (1905) adhered closely to those outlined in Davis'
earlier report. These plans called for a masonry gravity arch
structure with two large spillways - one at each end of the
dam - to carry away excess floodwaters and prevent overtopping
of the structures. This type of dam, gravity arch, retains water
behind it by means of its weight and the compressive force of
By 1903, Reclamation Service engineers
were conducting initial work in preparation for the dam construction.
Building the monumental structure across the Salt River in this
inaccessible spot posed enormous challenges. The dam site was
linked to the capital city of Phoenix some 60 miles away by
only a few primitive trails through the Salt River Canyon. The
site was closer to Globe, a mining town of a few thousand residents
located 35 miles southeast of the dam site. Reclamation opted
for a road between Mesa and the dam, crossing some extremely
In addition to the road, numerous support
facilities were needed to bring the dam project to successful
completion. A diversion dam and power canal brought water to
the dam site to generate hydroelectric power during construction.
Some quarries provided limestone, sandstone, and clay needed
to produce cement and concrete, while others provided the great
stone blocks for the masonry dam itself. Plants built near the
dam produced sand and cement; logging and milling camps in the
Sierra Ancha Mountains to the east of the Tonto Basin supplied
lumber. Work on these ancillary facilities began in 1903.
It was three years from the start of
the project before the first stone block of the dam was placed.
This occurred on September 20, 1906. The contract for the dam's
construction had been awarded on April 8, 1905 to the low bidder,
John M. O'Rourke and Company of Galveston, Texas. The price
was $1,147,600 and they anticipated completing the dam within
two years. As it turned out, this time frame proved impossible
to meet due to continual delays that plagued the project.
Initial steps in the dam construction
involved clearing the foundation so that the masonry could be
placed directly on solid bedrock. In order to accomplish this,
water had to be diverted around the site. Temporary upstream
and downstream cofferdams and a timber flume intended to channel
water through the damsite were designed for this purpose. Heavy
flooding destroyed or damaged these features on several occasions,
severely disrupting progress. After serious flooding in November
1905 destroyed the upstream cofferdam and timber flume, O'Rourke
and the Reclamation Service agreed that reconstructing the flume
would be useless; they decided instead to use the sluicing tunnel
already drilled through the south canyon wall as the exclusive
means of diverting water around the damsite.
On June 13, 1906, water began to flow
through the sluicing tunnel and the job of clearing the foundation
could begin in earnest. Once all dirt and loose rock had been
removed from the foundation, the next step was the placement
of masonry. The contractor had opened a quarry above the damsite
on the north side of the canyon to quarry the sandstone blocks
and smaller spalls. Large stones blasted from the quarry were
further reduced in size using a non-explosive method known as
"plug and feather." This method was used to avoid
any explosive shocks that could damage the rock.
Once quarried, stone was transported
to the dam by two 1200-foot long Lidgerwood cableways that extended
from one side of the canyon to the other, 350 feet above low
water. These cableways supported buckets that could be moved
horizontally and lifted vertically. With a capacity of ten tons,
they had the ability to haul extremely massive stones. The buckets
also transported large quantities of mortar and concrete from
the mixing plant to the dam. The mortar and concrete were delivered
to the dam at completely different times than the large stones.
The latter were always carried at night to the general location
where they would be laid up the next day. During daytime, the
cableways were used to carry mortar and concrete directly to
the particular site where masonry was in the process of being
along the parapet wall of the dam.
National Historic Landmarks photograph.
The actual process of building the dam
was actually quite straightforward. Stone delivered by the cableways
was placed near its final position by one of five wooden derricks.
Then the cableways delivered a batch of mortar and dumped it
where the stone was to be embedded. Shortly after, the stone
was lowered slowly onto the mortar and tamped down lightly to
eliminate any voids or air pockets. In the vertical spaces between
the stones, O'Rourke's crew placed concrete and filled the large
spaces with spalls. The masonry was kept wet for several days
to make sure that it set properly without prematurely drying.
After this, the stones and concrete were ready to form the base
for another stepped layer of masonry.
By June 1909, the dam had reached a height
of 170 feet at the south end and 100 feet at the north. It was
almost 75% complete, by volume. That same month, the first two
of six planned generating units in the permanent power plant
were put into operation. A third unit was placed in service
in August 1909 after which the temporary power unit was dismantled.
The transformer house was completed at the same time. Both the
power plant and the transformer house were built by government
The following June, the Reclamation Service
declared the dam to be "practically complete" except
for a small amount of work remaining to be done on the parapet
walls, the spillways, and the reinforced concrete bridges over
the spillways. When the final stone was laid in Roosevelt Dam
on February 5, 1911, the dam contained a total of 344,000 cubic
yards of masonry. A month later, amid great fanfare, the dam
Roosevelt Dam was designated a National
Historic Landmark on May 23, 1963. In 1984, the Secretary of
the Interior approved the modification of Roosevelt Dam as a
part of the Central Arizona Project's Plan 6. Modifications
were designed to meet Safety of Dams standards and for flood
control purposes. Engineers had determined that the dam could
not safely release water during a maximum flood event. In addition,
an event called a maximum credible earthquake occurring near
the dam could potentially cause it to fail. Subsequent to the
modifications begun in 1989 and completed in 1996, Roosevelt
Dam has a completely altered appearance. The original rubble-masonry
gravity arch dam is now encased in a new concrete block structure.
The original dam had a structural height of 280 feet and measured
723 feet long at the crest; the dam now has a structural height
of 357 feet and a crest length of 1,210 feet. After modifications,
the dam no longer retained integrity of design, materials, workmanship,
feeling, or association.
Accordingly, the Landmark designation
of Roosevelt Dam was withdrawn on March 10, 1999. The Theodore
Roosevelt Dam National Register District remains listed on the
National Register of Historic Places. This district contains
resources associated with the initial construction of Roosevelt
Dam, but the dam itself is a noncontributing structure.
view of the reconstructed Roosevelt Dam with Roosevelt Lake
Bridge in the background.
Bureau of Reclamation photograph, by J. Madrigal, Jr., 1996.