is the focus of this module?
Studying in teams, students examine a broad array of information
on the Lower Wheeling Creek and the Wheeling Creek watersheds in
Wheeling, West Virginia. The Lower Wheeling Creek Situation presents
a sub-section of the larger Wheeling Creek watershed database. In
order to resolve Situation 2 (Wheeling Creek Watershed), it is essential
that students solve Situation 1 (Lower Wheeling Creek).
are the compelling problems that students will face in this module?
In Situation 1,
Lower Wheeling Creek, students are asked to "wrestle with this
mess" of data and decide if there is a water quality problem
in lower Wheeling Creek. If so, what is the source of the problem?
About the data
These are real
data collected in May 1993:
The biological data
points represent the average of three macroinvertebrate samples.
The chemical and physical data points are single readings.
The data are continuous
from upstream to downstream, left to right.
Distance from the Ohio
River (mouth of Wheeling Creek) is a continuous gradient; therefore,
the use of lines to connect the points is appropriate.
It is accurate to interpret
changes in the lines as changes in water quality characteristics
as you pass from one point to the next.
Lower Wheeling Creek
Sites F and E (lower
2 sites), 2.6 and 5.4 km upstream have sewage from a leaky CSO;
dredging of the streambed beginning over 100 years ago; and some
acid mine drainage.
Site D, 6.2 km upstream
from the Ohio River has proximity to urban sites, and a parking
lot. Recent dredging produced a in few large rocks and siltation.
Sites C and B, 7.4 and
10.6 km upstream are good sites on Lower Wheeling Creek. They show
green space with no dredging.
Site A, 12 km upstream
is a relatively good site but appears to suffer from its proximity
to urban areas around Elm Grove.
In Situation 2,
Wheeling Creek Watershed, data from six sites in the Wheeling Creek
watershed are displayed from the small headwater tributaries to
a large, swimmable creek. Students are asked to answer several questions
based on their experience with the Lower Wheeling Creek problem
and the data provided regarding the entire Wheeling Creek watershed:
- Would you swim in
- How would you know
if the water was safe?
- If you caught a fish,
would you eat it?
- What are the most
important influences on Wheeling Creek?
- Is there anything
that can be done to improve water quality in the Wheeling Creek
tasks will students encounter as they work through this module?
Each team should identify a water quality variable (macroinvertebrates,
number of taxa, diversity index, EPT index, pH, Conductivity, Hardness,
oxygen, velocity, depth, rock size, and forest canopy) and analyze
it for the following:
- What does the variable
- How is it measured?
- What does it tell
you about pollution?
- How does it change
from site to site?
- How do the values
at the six sites on Lower Wheeling Creek compare with the average
of all 100 sites in the watershed?
is the role of remote sensing in this module? The role
of remote sensing in this module is limited to helping students
answer the question, "Is decreasing forest canopy directly
related to the decline in macroinvertebrates?" If not, lack
of tree cover is certainly symptomatic of the larger (urbanization)
problem, which may in turn account for the decline in some way.
The amount of concrete and the tree cover differences between sites
are very apparent in the low-level aerial photos. Ask students to
compare (visually) or measure (using image analysis) the amount
of green space and the amount of concrete in the photos. Do the
patterns parallel those of the biological data?
Checklist--have you thought of everything?
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:
Make a list of all of
the variables that could have caused changes in stream water quality.
Which of these variables
could change the water quality in Lower Wheeling Creek?
Additional Questions and Answers
Can you recognize a water quality problem?
The abrupt decrease in
the number of macroinvertebrates at 5 kilometers is particularly
noteworthy. Note also the low diversity and quality (EPT) values
at the 5 km site and the site just upstream. This is a complicated
problem but students should note that some changes occur in the
biological communities in the lower portion of the creek. The ultimate
challenge is for the student to investigate and determine what the
problems may be.
Can you make an assessment
of water quality by looking at the macroinvertebrate population?
abundant at most sites, except downstream, where pollution causes
populations to dwindle. The number of kinds of organisms (taxa),
a measure of diversity, drops off as well. The macroinvertebrate
quality index EPT shows a rather dramatic response through the Lower
Wheeling Creek area, indicating an increase, followed by a decrease
in the most pollution-sensitive organisms.
How many macroinvertebrates
occur at each of the six sites?
From 15,000 at the lowest
to 100,000 per square meter at the highest site.
How many kinds (taxa)
of organisms were found at each sites?
Between 9 and 28 kinds
What are the similarities
and differences between sites? Is there a pattern?
The decline in numbers
and kinds at the site that is 5 kilometers above the mouth indicates
pollution. Judging by the EPT index, the sites at 6 kilometers downstream
and beyond appear to have lower numbers of mayflies, stoneflies,
Does water chemistry
change from site to site? What does water chemistry data tell you?
Note that there is slight
pH level decline through Lower Wheeling Creek. There is also an
increase in conductivity associated with higher hardness values,
indicating an increase in metal and ion concentrations. These may
be attributed to greater amounts of concrete, urban runoff, CSOs,
and some mine drainage coming in 5 km upstream of the site. Note
particularly the decline in dissolved oxygen concentrations at the
lower two sites. This decline is related directly to the leaky CSO
pictured in the site description. This outlet, now fixed, was leaking
raw sewage into the stream at the time of sampling. The low dissolved
oxygen levels are probably most responsible for the decline in macroinvertebrate
abundance and diversity at the lower two sites. Other forms of pollution
are difficult to identify. Thus, in one sense the lower two sites
represent the cumulative impact of human settlement on the biological
communities of Lower Wheeling Creek.
Do trends in water chemistry
parallel the biological data?
It is especially challenging
for students to relate two or more kinds of data. Note the similarity
between the macroinvertebrate and the dissolved oxygen data. Both
decline tremendously at the lower two sites. Note the contrast between
the macroinvertebrate and the other chemistry variables.
Do the physical characteristics
of the sites play a role in determining biological water quality?
Certainly the relationships
between width, depth, and flow help shape the habitat for macroinvertebrates.
Note that forest canopy and stream rock size parallel the patterns
seen in the macroinvertebrate data, whereas depth and velocity do
The size of the rocks
in the streambed is a determinant of the types of organisms that
will live in any particular spot in a stream. Note that reduction
in rock size most characteristically follows the pattern shown in
the EPT index data. Is rock size important to survial of the mayflies
(E), stoneflies (P), and caddisflies (T)?
Finally, what is the
most important factor in determining the composition of the stream
community? This is a good subject for debate.