Hoover Dam: Conquering the Mighty Colorado River

(1) Hoover Dam, sometimes referred to as Boulder Dam, was constructed between 1931 and 1935 to harness the waters of the wild Colorado River. (2) The dam was a challenging task for even the most experienced professionals. (3) Many have called Hoover Dam a wonder of the modern world because of its unprecedented massive size and its designers’ ingenuity in overcoming obstacles that were considered impossible barriers at the time (Stevens).
(4) Hoover Dam is 726.4 feet high, more than twice the height of the highest dam built before it. (5) It is 1,244 feet across the top and 660 feet thick at the bottom. (6) It weighs 6.6 million tons and contains more than 3.25 million cubic yards of concrete (“Hoover Dam”).
(7) Hoover Dam set the precedent for modern dam-building technology, though there are higher and more massive dams today.
(8) The engineers who designed Hoover Dam came up with ingenious solutions to the problems of building such a massive concrete structure. (9) For example, they first had to figure out how to force the river to flow around the construction site. (10) To solve this problem they built four huge diversion tunnels to take the water through the canyon walls while they were building the dam. (11) Another seemingly insurmountable problem was that the concrete would have taken over a century to cool completely if it had been poured in one huge form. (12) To overcome this, the engineers came up with a building-block system and a network of cooling tubes to speed the process. (13) Engineers also invented a complex system of cables and pulleys to transport materials and workers up and down the sides of the canyon and across the face of the dam. (14) These and other innovations are reasons why Hoover Dam still stands as a monument to human ingenuity (“Hoover Dam”).
(15) Along with being massive and ingenious in its construction, Hoover Dam was also built in an amazingly short period of time. (16) More than 5,000 men found jobs during the Great Depression working on the dam. (17) Ila Clements-Davey, a dam worker’s daughter, said, “The men were just swarming over the whole place, they just looked like a hill of ants” (The American Experience). (18) However, working conditions were harsh.
It was a brutal job under the best of circumstances. But the summer of 1931 was one of the hottest on record. The men worked in blistering heat without shade or adequate drinking water. Workers collapsed from the heat. . . . (The AmericanExperience).
(19) Shifts were long. (20) Carbon monoxide poisoning from the trucks’ exhaust fumes was common. (21) Falls from the canyon walls and other work-related accidents were unfortunately common as well. (22) Workers were paid $4.00 per day. (23) Work never stopped on the dam—the men worked in three shifts, around the clock, to complete the job on time (The American Experience). (24) Not only did they complete it on time, but they beat the government’s deadline by more than two years!
(25) The energy harnessed behind the dam provided power to the populations of Arizona, Nevada, and California, and the water of the newly formed Lake Mead would provide fresh water and irrigation for the same region (“Story of Hoover Dam”). (26) Human beings had conquered the mighty Colorado, which had flowed unchecked and wild for millions of years.
(27) President Herbert Hoover, for whom the dam was named, summed up the achievement in these words:
Civilization advances with the practical application of knowledge in such structures as the one being built here in the pathway of one of the great rivers of the continent. The spread of its values in human happiness is beyond computation.
(28) Hoover Dam is an amazing example of how humans harness the forces of nature.

Works Cited

The American Experience: Hoover Dam. Dir. Stephen Stept. Videocassette.
PBS Video, 1999.

“Herbert Hoover and the Colorado River.” Hoover Dam. U. S. Department
of the Interior, Bureau of Reclamation. 16 April 2002.
.

“The Story of Hoover Dam.” Hoover Dam. U. S. Department of the Interior,
Bureau of Reclamation. 16 April 2002.
.

“Hoover Dam: Source of the American West’s Oasis Civilization.”
SunsetCities. com. 16 June 2002.
.

Stevens, Joseph E. Hoover Dam: An American Adventure. Norman and
London: University of Oklahoma Press, 1988.

Which is the BEST revision of sentence 7 to provide variety and prevent it from being too similar to the structure of the other sentences in the paragraph?
a.
It is no longer the country’s highest or most massive dam, but Hoover Dam set the precedent for modern dam-building technology.
b.
There are higher and more massive dams today, but Hoover Dam set the precedent for modern dam-building technology.
c.
Though there are higher and more massive dams today, Hoover Dam set the precedent for modern dam-building technology.
d.
Leave as is.