What is the focus of this module? Studying in teams, students examine a broad array of information on Bear Creek. Bear Creek Watershed, including the community of Oak View and all of its inhabitants, is a composite of many fairly rural communities and the water quality problems commonly found there - any resemblance to an actual location is completely unintentional. The biological, chemical, and physical data for this watershed are realistic values based on those found in similar situations. We developed this module to allow the students the opportunity to examine various aspects of water quality in a realistic situation.

What are the compelling problems that students will face in this module?
They are being asked to determine the cause of a fish kill, track down the source of the pollutant(s), and suggest steps toward remediation. A biologist faced with a problem like this would typically measure various biological, chemical, and physical parameters at the site in question, then move upstream, measuring those same parameters in each tributary entering the main stream.

What tasks will students encounter as they work through this module? Each team of students should identify biological, chemical, and physical water quality variables. Such variables include: number of macroinvertebrate taxa; EPT index; Shannon Index of Species Diversity; pH; alkalinity; hardness; nitrates, nitrites, and ammonia; ortho- and total phosphate; dissolved oxygen and biochemical oxygen demand; fecal coliform; conductivity and density; elevation and catchment area; stream order; forest canopy; stream width, depth, and velocity; rock size; turbidity; total solids; temperature). The students should analyze these variables for the following:

• What does the variable represent?
• How is it measured?
• What does it tell you about pollution?
• How does it change from site to site?

The chemical and physical assessments of water quality are conducted by directly measuring variables. The data from the chemical and physical assessments of sites along Bear Creek are provided to the students in the module (see the "Bear Creek Watershed" puzzle piece). The number of individuals in each order of macroinvertebrates found at each site along Bear Creek is also provided to the students. However, to conduct a biological assessment of water quality, students must perform two calculations on the macroinvertebrate data. These calculations are the EPT index and the Shannon Index of Species Diversity. (Examples of these calculations using Bear Creek data.)

Remote sensing is used in two ways in this module. One is a common use of the tool--as a way to measure canopy cover. Satellite images differentiate among soil, water and vegetation by the type of light reflected. In this way, the amount of vegetation that overlaps the boundaries of streams can be determined. In addition, pictures like the one below taken from airplanes can show distinct landforms such as forests, pastures, and tilled lands, in addition to highways and waterways. These remotely sensed images can be used to track down possible sources of pollution.

The second way remote sensing is used in this module is as a tool to measure rock size. Representative samples of rocks are collected, placed on white pans, and photographed. The photographs are then analyzed using video image analysis. By "counting" the number of pixels each rock occupies, the image analysis software calculates the exact area of each rock (see the photo below).

Preparation Checklist--have you thought of everything?

Creating a Working Problem Statement
To help students create a Working Problem Statement (WPS), you may want to pose some introductory questions such as the following:

How does stream water in Bear Creek Change as you move upstream from Taylor's Trout-A-Rama?

What pollutants can cause changes in stream water quality?

Which of these pollutants could have changed the quality of water in Bear Creek?

Can you assess water quality by looking at the macroinvertebrate population?

What does water chemistry data tell you?

Does water chemistry change from site to site along Bear Creek?

Do trends in water chemistry parallel the biological data?

What is the most important factor in determining the composition of the stream community? (This is a good subject for debate.)

Resources for this module

Teacher to Teacher
Water Quality Module Rubric

A Letter to Teachers

Assignment Ideas
Have teams report their findings for each of the variables. They may wish to use the blackboard or poster boards so they can easily compare their findings.

Have students compare chemical and physical data to biological data. Which chemical or physical variables mimic the trends in the biological data from upstream to downstream?

Ask students to prepare a list of the most (to least) likely causes of deteriorated water quality in Lower Wheeling Creek. Eliminate variables that don't seem to be associated with the deteriorated water quality. Which of the variables that appear to be associated with deteriorated water quality show the most dramatic change?