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.
are the compelling problems that students
will face in this module?
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.
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
does the variable represent?
is it measured?
does it tell you about pollution?
does it change from site to site?
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
using Bear Creek data.)
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.
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
Checklist--have you thought of
a Working Problem Statement
To help students create a Working Problem
Statement (WPS), you may want to pose
some introductory questions such as the
does stream water in Bear Creek Change
as you move upstream from Taylor's Trout-A-Rama?
pollutants can cause changes in stream
of these pollutants could have changed
the quality of water in Bear Creek?
you assess water quality by looking at
the macroinvertebrate population?
does water chemistry data tell you?
water chemistry change from site to site
along Bear Creek?
trends in water chemistry parallel the
is the most important factor in determining
the composition of the stream community?
(This is a good subject for debate.)