Classroom Ideas: Fifth-Eighth Grade
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Controlling the Flow of the Colorado River: A Study of Dams

OVERVIEW

Most of earth’s surface is covered by water. But it is not distributed evenly across the face of the planet. The construction of dams represents one effort to control water and make it more useful to people. This lesson investigates the human attempt to control the Colorado River.

Connections to the curriculum: geography, language arts, science, social studies

Connections to the National Geography Standards:

Standard 1: “How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective”
Standard 7: “The physical processes that shape the patterns of Earth’s surface”
Standard 14: “How human actions modify the physical environment”
Standard 15: “How physical systems affect human systems”

Time: One or two hours

Materials Required:

• Copies of a political map showing the western United States (two per student)
  
• List of dams along the Colorado River (see below)
  
• Colored markers or pencils
  
• One or more atlases with state maps for the United States
  
• Wall map of the United States

  Purpose:

  Examine a representative river system and determine the effects of dams along it

  Objectives:
  

  Students will:

  • Research and map the Colorado River and its dams
    
  • Predict the effects of a dam on an area
    
  • Suggest the reasons a dam would be built
    
  • Compare the Colorado River system with other major river systems within the United States and around the world

  SUGGESTED PROCEDURE

  Opening:
  
  

  1. Have your students brainstorm the reasons for building a dam.
  2. Explain the three main reasons:

  • flood control
    
  • water storage
    
  • hydroelectricity

  3. Locate the Colorado River watershed (the lands drained by the Colorado and its tributaries) on a map of the United States. Inform them that the Colorado River is more than 1,400 miles (2,250 kilometers) long and that its watershed covers more than 244,000 square miles (632,000 square kilometers).
  4. Propose questions to consider when studying dams:

  • What are the potential negative effects of dams on the environment, such as the displacement of some fish populations?
    
  • Are more dams built in any particular region of the United States than another?
    
  • Does any of your electricity come from hydroelectric power plants? If so, where are they located?

Development:

1. Have reference materials available for students.
2. Divide students into pairs.
3. Give each pair a set of colored markers or pencils and a copy of the map showing the western United States.
4. Use one color to trace the Colorado River from source to mouth.
5. Use a second color to highlight the tributaries that flow into the Colorado River.
6. Consulting state maps and the list of dams, use a third color to mark the locations of dams along the Colorado.
7. Have students use a fourth color to outline regions drained by the Colorado River. Discuss questions such as: “In areas near dams, is there more agriculture?” and “Is there any probable relationship between the population of a city and its location near a Colorado River dam?”
8. Have students label several large cities in the Colorado River watershed: Denver, Colorado; Grand Junction, Colorado; Farmington, New Mexico; Gallup, New Mexico; Flagstaff, Arizona; Phoenix, Arizona; Tucson, Arizona; Yuma, Arizona; Las Vegas, Nevada; Los Angeles, California; San Diego, California
9. Have students predict which communities depend on the Colorado River for irrigation, drinking water, or electricity.
11. Have students create a drawing of an area before and after a dam is constructed. They may consult the Geoguide Online dam for hints!

Closing:

1. Ask your students to summarize the use of dams on the Colorado River.
2. Have pairs of students display their maps of the dams, cities, and land use along the Colorado.

Suggested Student Assessment:

Labeling of the maps

Written assignment on the effects of dams on the Colorado River

Extending the lesson:

Investigate and compare other dam systems within the U.S., such as the Tennessee Valley Authority and the Salt River Project.

Use newspaper archives and Internet sources to research controversies surrounding the construction and operation of dams.