1. Dams: Past, Present, and Future
Paras Patel
This is a mural that is on display at the Department of the Interior museum in Washington D.C.
The artist was William Gropper, and the mural was painted in 1939 and inspired by the construction of the Grand Coulee and Davis Dams.
It shows the construction of a great dam, in the 1930’s the Department of the Interior used the construction of dams to generate more jobs to help ease the conditions of the Great Depression

2. Hoover Dam
The Hoover Dam is located on the borders of Nevada and Arizona, on the Colorado River.
Construction on the Hoover Dam began in 1931 and was completed in 1935.

3. Hoover Dam
The dam was built due to the cycles of drought and flood that had prevented agricultural growth in the southwest.
The dam would also provide hydroelectric power and water supplies so that surrounding cities would be able to flourish.
The animation here shows how a “typical hydroelectric dam” works, basically water runs through the turbine, which is fan-like structure that is turned by the water flowing through it. The turbine is usually connected to a generator which converts the turning of the turbines into electricity, finally the electricity is then sent out from the powerhouse across power lines to where it’s needed

4. Hoover Dam
What type of ecosystem do you expect to be present around the Hoover Dam?
How do you think the ecosystem has changed since the dam was built?
Ask the students if any of them have been to the Hoover Dam, or the area in question. If they have, ask them what the area was like.
Ask them what they think a dam does to the environment upriver of the reservoir area, and downriver past the dam.
The reservoir area will have an abundance of water and all that this new found water entails. Whereas downriver there may not be as much water, therefore a change in the ecosystem will result.
Ask the students what steps they think can be taken to aid with the environment.
Basically the area is arid or semi-arid, as indicated on the map above
An arid climate is usually a desert type climate.
A semi-arid climate is usually a grassland type climate and receives more rain than an arid region.
When asking how the ecosystem or climate has changed, make sure the students know what has taken place upriver and downriver relative to the dam.
Basically upriver where a reservoir will form, the environment along the river, if more arid, may become more lush due to the abundance of water.
The control of water flowing downriver may make the environment more “dry” due to a lack of water.
BOTH have an effect on vegetation, land, and animals accordingly.
TEKS Science:
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions

5. Hoover Dam
The benefits of building this dam include water supplies for major cities and agriculture, as well as hydroelectric power for surrounding areas.
This dam also put a stop to the drought and flood cycle that had been occurring for such a long period of time.
The costs of building this dam, along with other dams on the Colorado river, include a decline in fish in the river and changes to the surrounding ecosystem.

6. Hoover Dam
Some steps have been taken to try and reduce the steady decline of fish inhabiting the river.
Fish ladders have been built at dams so the fish can still go upstream to spawn.
Bypass tunnels have been made for fish traveling back downstream.
Fish ladders are basically what they seem to be ladders of water that make it possible for fish to surpass a dam, through a mild slope with steps and flowing water, they are made to emulate conditions that would be present when a fish is going upstream.
Bypass tunnels are tunnels built for fish coming back downstream, they bypass turbine areas where the fish may get killed because of the turbine blades. This is done with the help of tunnels that are full of water that go around the dam or at least around the turbines.

7. Hoover Dam
Do you think it was a good idea to build this dam? Think about the costs and the benefits, and the effects each of them has had.
Should the dam be torn down or should it be left alone?
The Hoover Dam is still standing today. The government thinks that the benefits that this dam produces far outweigh the costs. The benefits being the production of hydroelectric power and water supplies for a far spread area of agriculture.
Ask the students if they believe that this dam was a good idea or not, why or why not?
Ask the students whether the dam should be torn down in the future or left alone, ask for justifications for each answer.
The costs are still present but steps, such as the fish ladders are being taken to try and lessen the effects.
The dam should be left alone in this case, but steps can always be taken to try and alleviate some of the costs that the dam will incur.
Steps, like fisheries starting a more intense fish repopulation program, or other things like an environmental conservation program in the effected areas
Try to get the students to give you ideas of how the dam can take steps to try and alleviate some of the negative effects caused by the dam.
6.1 (B) Make wise choices in the use and conservation of resources
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions

8. Edwards Dam
The Edwards Dam is located on the Kennebec River in Augusta, Maine.
The dam was completed in 1837.

9. Edwards Dam
There was much protest and controversy when this dam was proposed. The area where the dam was to be built was populated with fish that swam upriver to spawn. Many fisheries were located up and down the river.
A fish ladder was created when the dam was built but it washed away and was never replaced.
What would happen to the fish if a dam was built in the river? Remember that fish need to swim upstream to spawn.
Ask the students what they think will happen to the fish once a dam is constructed in a river. If there is a fish ladder, will the amount of fish going upriver be the same or less?
Because, in this case, there is no fish ladder, ask the students what they think will happen to the fish. Also ask them what will happen to the fish after a long period of time with the absence of a fish ladder
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions
6.12 (C) Identify components of an ecosystem to which organisms respond

10. Edwards Dam
The Edwards Dam was built despite all of the protest and controversy. It powered seven sawmills, a gristmill (a mill for grinding grain) and a machine shop.
The Edwards Dam was not initially designed to generate electricity. The first electric generators were installed in 1913.

11. Edwards Dam
There were some benefits when the dam was initially built, such as providing mechanical power for the mills, and generating a small amount of electricity.
In more recent years the dam was only used for the small amount of hydroelectric power it produced.

12. Edwards Dam
The costs of building this dam included a loss of habitat for nine species of migratory fish. These fish had been coming from the ocean to spawn in the Kennebec River for thousands of years.
The lack of habitat, and the lack of a fish ladder, led to a total decimation of the fish population in the river.
The dam was also breached (broken through) several times, which cost the dam company a lot of money to fix.

13. Edwards Dam
Think about the costs and the benefits that the dam had. Was it a good idea to build this dam?
Weigh the costs and the benefits. Do you think this dam should be torn down or left alone?
Remind everyone that they must think about all the effects, positive and negative, including effects on the environment that were not specifically mentioned but have taken place.
Ask the students whether they believe it was a good idea to build this dam, why or why not?
Ask the students whether the dam should be torn down or left alone, tell them to give justifications for their answers.
The benefits as mentioned may have started out well, but in recent times the dam did not produce much of anything.
Another strike against this dam was the fact that the fish ladder was not rebuilt after being washed away.
Also another thing was the costs of fixing the dam every so often due to breaches in it’s walls.
In this case the costs tend to heavily outweigh the benefits of this dam. The government also thought this and it was the first dam to ever be removed by the government (shown in the next slide).
6.1 (B) Make wise choices in the use and conservation of resources
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions

14. Edwards Dam
Before
After
The Edwards Dam was the first dam to be demolished by the government, because the costs heavily outweighed the benefits. It was removed in 1999.

15. Three Gorges Dam
Licensed under the GNU Free Documentation License.
The Three Gorges Dam is currently being built on the Yangtze River in China.
The dam will be completed in 2009.

16. Three Gorges Dam
This dam is going to be the largest hydroelectric dam ever built.
It is going to produce a capacity of around 18.2 million kilowatts of power; this tops the largest dam right now by 40 percent.
Picture by Thomas R. Danford, West Virginia Northern Community College

17. Three Gorges Dam The idea for this dam was first proposed in 1919.
Planning for the construction of this dam began in 1954.
One of the purposes of this dam is to supply power to much of central China and its growing economy.
Another purpose of this dam is to relieve the cycles of heavy flooding. A flood in 1954 killed 30,000 people and left one million people homeless.

18. Three Gorges Dam
This is the Three Gorges Dam, in the process of being built, on July 20, 2000

19. Three Gorges Dam
The benefits of this dam include generating enough power to keep pace with China’s economic growth and minimizing the danger of flooding. It will also reduce fossil fuel emissions so that there is less stress on the atmospheric environment.

20. Three Gorges Dam
The costs of building this dam include moving and resettling more than 1.1 million people, increased risk of landslides and earthquakes, and damage to the natural habitats in and around the river.
Besides the many fish species that will be at risk, the Yangtze Dolphin, the Chinese Sturgeon, the Chinese Tiger, the Chinese Alligator, the Siberian Crane, and the Giant Panda will also be affected by the building of this dam.
Ask the students how they would feel if they were asked to leave their land and move from fertile farm lands to worse conditions.
Mention that these people are peasants and do not have much money.

21. Three Gorges Dam
Think about the costs and the benefits, and the effects each of them will have. Do you think it’s a good idea to build this dam?
What effects do you think the dam is going to have on the surrounding environment?
Whether building this dam is a good idea or not is a very debatable issue. Since this dam is not completed yet, there is no sure way of knowing what the outcomes, positive or negative, will be.
Ask the students whether they think building this dam is a good idea or not. The answers may differ, but this is expected since there is no wrong answer in this case. Also ask them to justify their answer with examples from the PowerPoint.
Ask the students what they think will happen to the environment on both sides of the dam. Also ask them if these effects are going to be positive or negative, along with a justification for their answer.
6.1 (B) Make wise choices in the use and conservation of resources
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions

22. Three Gorges Dam
When the dam is built what steps can be taken to alleviate some of the problems the dam will cause?
First ask the students what they believe the major negative effects of building this dam will be (i.e. a decrease in fish population, habitat decimation for many other animals, landslides, etc.).
Next ask the students what steps can be taken to alleviate the problems that will arise. Also ask them how they would go about solving the problems.
6.1 (B) Make wise choices in the use and conservation of resources
6.2 (A) Plan and implement investigative procedures
6.2 (C) Analyze and interpret information to construct reasonable explanations
6.2 (D) Communicate valid conclusions
6.12 (C) Identify components of an ecosystem to which organisms respond

23. Update: Three Gorges Dam
Work in some areas of the dam has been suspended, because the lack of proper approval by China’s State Environmental Protection Administration (SEPA).
The SEPA claims that there was a lack of proper environmental impact checks at the underground power station under review
China has also suspended 30 other large –scale projects in an effort to improve their environmental credentials.
As of February the Three Gorges Project Corp is refusing to stop work on some of the questionable sites despite government orders, they will most likely be fined for these actions