Smithsonian National Zoological Park l Friends of the National Zoo



Settle Down: Turbidity and Water Quality


Healthy water is necessary to sustain life. All living things need water. Bodies of water also provide habitat for organisms. Humans need water too, for basic reasons such as drinking as well as for recreation, inspiration, and commercial activities.

Water quality refers to the physical, biological, and chemical properties of water that affect a wide range of ecological processes within a watershed. Likewise, natural processes, such as heavy rain and snow melt, and human-related factors, including urban development and agricultural activities influence water quality in a particular area, or watershed.

There are many ways to measure scientifically water quality and thus assess the health of water and how it changes over time and under varying conditions. Scientists use various techniques to monitor physical and chemical properties of water, such as pH, temperature, salinity, and turbidity, as well its biological properties, such as the presence or abundance of phytoplankton, aquatic invertebrates, and amphibians.

In this activity, students will focus on one measure of water quality: turbidity. Turbitity is the cloudiness of water, caused by suspended solids.

The outdoor activity was adapted from an activity, “Muddying the Waters,” from the educational series, Lessons from the Bay by the Virginia Department of Education.


Students will be able to:

  1. Demonstrate a scientific method of measuring turbidity.
  2. Measure quantities in customary and metric units, and use increments of time as a control while conducting an experiment.
  3. Relate turbidity to the ability of light to penetrate a water column.
  4. Describe the relationship between turbidity and the ability of aquatic plants and animals to derive energy from sunlight.
  5. Understand cause-and-effect relationships between human activities on land and the health of bodies of water locally and globally.
  6. Brainstorm how to conserve soil and reduce local sources of sediment and pollution, to protect and maintain healthy water resources.

Let's Get Started

Step 1

Print out all worksheets and datasheets. Each student will likely need a copy.

Step 2

Follow the link below to the first step of the online student lesson.