Lab 6: Drying of the American West

The lab activity described here was created by Betsy Youngman of Phoenix Country Day School and LuAnn Dahlman and Sarah Hill of TERC for the EarthLabs project.

Summary and Learning Objectives

When populations live in areas where natural resources are scarce, conserving the resources becomes critical for survival. The case study presented in this lesson introduces students to a real drought that has been developing in the Colorado River basin for many years. The Colorado River is the major source of water for people in the driest part of the United States. More than 30 million people in 7 states depend on this river as the primary source of their water.

In this lesson, students discover how changes in climate over the Colorado watershed are reducing the amount of fresh water available in the river. They also see how the population of the region that uses this water has grown, resulting in increasing demands on a dwindling resource.

After completing this investigation, students will be able to:
  • Visualize the geographic location and scale of the Colorado River Basin.
  • Use tabular data to generate and interpret graphs of water consumption in the states supplied by the Colorado.
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Context for Use

In this activity, students learn about the impending issue of water scarcity in the Colorado River Basin. Because of its "real world" rather than theoretic nature, the activity can be used as an introductory case study to stimulate student interest in drought, or as a culminating activity in which students can apply what they've learned about drought to the current situation in the Colorado River Watershed.

Time Required

  • Parts A and B: 1 hour; could be assigned as homework
  • Part C: Graphing - 30 minutes (if students are familiar with Excel)
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Activity Overview and Teaching Materials

In Part A, students read an article and a view a short video that describe the situation at Lake Mead, a reservoir on the Colorado River system. Students view an online base map of the basin and gain a general sense of the region.

Part B has students read the article Climate Change is Shrinking the Colorado River that addresses how climate has changed across the Colorado River Basin. The article is based on the study by the same authors, The twenty‐first century Colorado River hot drought and implications for the future. Students view a short video about how snow impacts a watershed. They also explore the root causes of the changing reservoir levels in Lake Mead by reading about the source of the river's water and how short-term climate variations such as ENSO affect river volume. Students consider a graph of the river's reconstructed natural flow to discover that less water is entering the river system over time.

In Part C, students graph water consumption data from the Bureau of Reclamation - data after 2006 can be found in the Bureau's Water Accounting Reports. This activity requires the use of a spreadsheet program, such as Excel.

Printable Materials

You may want to provide a hard copy of the activity sheet (Acrobat (PDF) 44kB Dec18 18) on which students can record their answers. A

word processing document

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of the activity sheet that includes suggested answers is also available. Educators are encouraged to customize the questions and add new ones to meet specific learning goals in your location.

Teaching Notes and Tips

Parts A and B require students to read several articles and study graphs. Depending on student experience this can be assigned as a homework assignment, allowing more time in class for the more interactive Part C.

Part C includes instructions for viewing tabular data from the BLM and graphing it using a spreadsheet program such as Excel. To avoid connectivity or bandwidth issues, you may want to download the spreadsheet file and make it available on student computers in the days preceding the lesson.


You can assess student understanding of topics addressed in this Investigation by grading their responses to the Stop and Think questions. Additional assessments include having students present their thoughts and impressions from the reading assignments to their classmates.

State and National Science Teaching Standards

Applicable California Science Teaching Standards

Earth Science - Energy in the Earth System

California Geology

  • 9.3. Students know the importance of water to society, the origins of California 's fresh water, and the relationship between supply and need.

Investigation and Experimentation Standards

a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.

g. Recognize the usefulness and limitations of models and theories as scientific representations of reality.

m. Investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings. Examples of issues include irradiation of food, cloning of animals by somatic cell nuclear transfer, choice of energy sources, and land and water use decisions in California

Applicable Massachusetts Science and Technology Standards (PDF - 1.3 Mb)

Earth and Space Science - Earth Processes and Cycles

  • 1.8 Ground-based observations, satellite data, and computer models are used to demonstrate interconnected Earth systems.

Applicable New York Core Curricula

Physical Setting/Earth Science (PDF - 135 Kb)

STANDARD 4 - Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.

  • Key Idea 2. Many of the phenomena that we observe on Earth involve interactions among components of air, water, and land.
    • 2.1g Weather variables can be represented in a variety of formats including radar and satellite images, weather maps (including station models, isobars, and fronts), atmospheric cross-sections, and computer models..

STANDARD 6 — Interconnectedness: Common Themes. Students will understand the relationships and common themes that connect mathematics, science, and technology and apply the themes to these and other areas of learning.

  • Key Idea 2. Models are simplified representations of objects, structures, or systems used in analysis, explanation, interpretation, or design.

Applicable North Carolina Earth and Space Science Standards

1.02 Design and conduct scientific investigations to answer questions related to earth and environmental science.

  • Analyze and interpret data.

5.02 Evaluate meteorological observing, analysis, and prediction; meteorological data depiction.

5.03 Analyze global atmospheric changes; changes in weather patterns.

Applicable Texas Essential Knowledge and Skills (TEKS)

  • (10) Science concepts. The student knows the interactions that occur in a watershed. The student is expected to:
  • (B) analyze the impact of floods, droughts, irrigation, and industrialization on a watershed; and

Applicable National Science Education Standards (SRI)

Science as Inquiry (12ASI)

Abilities necessary to do scientific inquiry

  • 12ASI1.3 Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

Natural and Human-Induced Hazards

  • 112FSPSP5.3 Some hazards, such as earthquakes, volcanic eruptions, and severe weather, are rapid and spectacular. But there are slow and progressive changes that also result in problems for individuals and societies. For example, change in stream channel position, erosion of bridge foundations, sedimentation in lakes and harbors, coastal erosion, and continuing erosion and wasting of soil and landscapes can all negatively affect society.

Additional Resources

Background Information (added 14Dec)

US Dept of Interior - Drought in the Colorado River Basin

NASA Earth Observatory - 25 Years of Drought in Las Vegas

Scripps Oceanography - Welcome to the New Normal April 2008

Content Extension

  • The non-fiction book, Cadillac Desert by Marc Reisner, delves deeply into the historical and political issues of water in the American West. The Wikipedia entry for Cadillac Desert provides an overview.
  • University of Arizona's Institute for the Study of Planet Earth's Climate Assessment for the Southwest (CLIMAS) program offers further information and links to current research on the climate of the Southwestern United states.