Hoover dam and the negative effects on environment

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The great Hoover dam:

I. Overview:

Hoover dam was located on Colorado River, the natural canyon border between Arizona State and Nevada State.

The dam was named after the 31st USA president, Mr. Herbert Hoover. Herbert Hoover was the person who planned building a huge dam on Colorado River, and with the help of him, Colorado compact, which was Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming agreement to device amount of river’s water, was signed.

I. Overview:

Hoover dam was built in the time of Great Depression as a mean of dealing with the unemployment (1931).

Hoover dam cost 49 million USD. People had to move 1.150.000 cu m of raw material to begin the construction. Thousands of worker created such great result: Hoover dam, the Concrete Arch Gravity dam which has 379m high, 221m tall and 201m wide at its base.

Lake Mead is the reservoir of the dam.

II. The negative effects on environment

1) Riverbed lowering,2) Greenhouse gases ejecting,3) Ecosystem destroying,4) Problems about the water.

1) Riverbed lowering

The groundwater table got deeper gradually after the construction of Hoover dam.

The reason was the lowering of Colorado riverbed. During 9 years, the water stored in Lake Mead kept digging the riverbed and it made the riverbed below Hoover dam get 4 meters deeper.

A bunch of bad effects happened. For instance, many plants in the floodplain were threatened, because they could not reach the new depth of the groundwater table.

2) Greenhouse gases ejecting

People use hydropower instead of fossil fuels so that there will be less greenhouse gases.

But the dams themselves ARE a great source of greenhouse gases such as CO2 and CH4 (25 times stronger than CO2)

The process:

Figure 2.1 Figure 2.2

The process:

Figure 2.3 Figure 2.4

3) Ecosystem destroying

Bighorn sheep Coyote Ground squirrel

Ringtail cat Desert tortoise Golden eagle

3) Ecosystem destroying

These animals are threatened by the existent of Hoover dam.

They live in a delicate balance that depends on specialized plant lives to survive. Because of the dam effects, these plants are destroy, and the animals take the consequences.

Not only that, the dam construction and human activities contribute a major part in destroying the Colorado River ecosystem with the change in watershed, the harnessing of water flow, the erosion of the riverbanks and the pollution resulting from increased vehicle traffic.

Desert plants:

BushesDesert flower

3) Ecosystem destroying

Many fish species have been affected by a number of specific aspects of the dam, most notably the change in water temperature. The Hoover Dam turbines lower the water temperature drastically, which resulted in the immediate extinction of several species of warm-water fish after the dam's completion in 1936.

Furthermore, introduction of rainbow trout, which are cold-water fish, for recreational fishing has created competition with native species for resources.

The impact of Hoover Dam also includes significant yearly erosion of the banks of the river as a result of poured concrete preventing natural silt deposits. This erosion has also affected the feeding and reproductive environments of the native species of fish.

Endangered fishes in Colorado river:

Bonytail chub Colorado pikeminnow

Humpback chub Razorback sucker

4) Problems with water

Temperature and Chemistry: the temperature of the water below the dam is usually not as high as it would be before the dam and often remains unchanged, not affected by the natural seasonal variations. Similarly, the chemistry of the water may be altered. The free-flowing water usually has higher oxygen level and lower dissolved salts level than the water in the Lake Mead.

Evaporation: 350 billion gal (1.3 trillion liters) per year because Lake Mead’s surface (640 sp km) is thousands of times larger than the Colorado River’s surface.

III. Conclusion

Hoover Dam has a lot of negative effects on environment of Colorado River, but we cannot destroy it. It is a wonder not only for USA but also for the World; moreover, its electricity production is safer than the work of nuclear power plants. What we discover from Hoover Dam can be useful for creating future hydraulic structures. We need to consider the environment before constructing such enormous structure; economic and environmental aspects must be balance so that we will not have to regret any more.

Appendix

Stone angel

Hoover dam’s penstock tower

Appendix

Lake Mead