Lesson 10 – How Does the Government Protect Public Water
Lesson 10 of a “Drinking Water: Protecting the Source” curriculum (USDA NRCS / EPA / National FFA), this lesson explains how the federal government protects public water through the Clean Water Act and Safe Drinking Water Act, covering the EPA’s role in setting water quality standards and specific contaminant thresholds (MCL, MCLG, action levels). It includes a hands-on measurement activity in which students measure objects and time in increasingly small units to calculate detection limits and explore the challenges of measuring contaminants in minute quantities.
At a glance
- Learning objectives
-
- 10.1 Describe the importance of the Clean Water Act and Safe Drinking Water Act.
- 10.2 Define the source and meaning of specific contaminant thresholds to ensure safe drinking water.
- 10.3 Describe how regulators determine specific contaminant thresholds that help ensure safe drinking water.
- Explain the methods used to calculate detection limits.
- Calculate detection limits on a set of data.
- Demonstrate how reporting data close to detection limits must be qualified with an accuracy statistic.
- Explain what happens to accuracy and precision as detection limits are set to increasingly lower levels.
- Time required
- 60 minutes
- Grade level
- 9-12
- Materials
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- SW.10.1.TM Slide: Gaps in Federal, State, and Local Standards and Regulations
- SW.10.2.SA Worksheet: Safe Drinking Water Thresholds — 1 copy for each student
- Slide SW.10.2.TM.A: Examples of Contaminants and Thresholds
- Slide SW.10.2.TM.B: Microbial Contamination by Bacteria or Viruses
- Slide SW.10.2.TM.C: Chemical Contamination from Fertilizers
- Slide SW.10.2.TM.D: Lead Contamination
- Slide SW.10.2.TM.E: Ensuring Safe Drinking Water
- Slide SW.10.2.TM.F: Enforcing Drinking Water Standards
- Stopwatch
- Small toy racing car
- Inclined surface
- Meter stick with cm divisions
- Meter ruler with mm divisions
- Scientific calculator
- Key Terms
- Accuracy; Action level; Maximum Contaminant Level (MCL); Maximum Contaminant Level Goal (MCLG); Method Detection Limit (MDL); Precision; Standard deviation; Uncertainty; Variance or random error
Downloads & Links
Aligned Standards
National Science Education Standards for Grades 9 – 12
- Content Standard AAbilities Necessary to Do Scientific Inquiry: Design and conduct scientific investigations.
- Content Standard AAbilities Necessary to Do Scientific Inquiry: Design and conduct scientific investigations.
- Content Standard EScience and Technology: Technology, by its nature, has a more direct effect on society than science because its purpose is to solve human problems, help humans adapt and fulfill human aspirations.
- Content Standard FScience in Personal and Social Perspectives: Natural Resources – Human populations use resources in the environment in order to maintain and improve their existence. Natural resources have been and will continue to be used to maintain human populations.