2. Overview
Our project was to determine the health of the
Mullet River. We did many tests at our site to help us
come to conclusions. We did a habitat assessment,
collected and identified macroinvertebrates, and
chose 3 water quality tests to complete. Our group
performed the phosphate, dissolved oxygen, and
pH tests, but also looked at other group’s data to
help us decide the river’s health.
3. Overall Health
We’ve discovered that the river isn’t very healthy.
Many of the tests we looked at had poor results. We
also found out that most of the test outcomes
occurred because of the silt and mud in the river.
Because there is so much mud piled at the bottom,
it causes extremely shallow water depths.
4. Sources of the Health
There are many point and non-point sources
contributing to the river’s health. They can affect
the health from any point in the river. Some of these
are:
Storm drains
Runoff
Septic systems
Dump leakage
Another major problem is the mud, which is caused
from all of the organisms that die and pile up on the
bottom. This affects the results of our tests.
5. Habitat Assessment
This was the very first test that we looked at. When
we added the 10 parameters together, we got a
score of 32/52. A couple of the major categories
we lost points on were:
The riparian zone
There is hardly any riparian vegetation along the banks.
This means that there is no stopping the flow of runoff into
the river.
In-stream habitat for fish
It’s easy to see that there aren’t many fish in the river. It’s
too shallow, and there aren’t any places for them to live.
6. Macroinvertebrates
Next, we went into the river and collected
macroinvertebrates. Using the Dichotomous Key,
we identified each organism we found. We placed
them into groups based on their sensitivity to
pollution. We didn’t find any in Group 1, which are
sensitive to pollutants, but we found organisms that
fit into every other category. The further they are
down the list, it means that they can tolerate higher
levels of pollution and very low levels of oxygen. This
is a good indicator of how little oxygen is present in
the river.
7. Dissolved Oxygen
We performed this test in the morning on two
different days. The first day, it was pouring and cold,
giving us an oxygen level of 47%. We got 84% the
next day, when it was warm and partly cloudy.
While looking at other groups’ data from other times
during the day, the percents were considerably
different. Since the numbers go up and down so
much, it means there is bacteria in the water that’s
using the dissolved oxygen faster than it can be
produced.*
Another factor that influences the changing
percentages is the water temperature. The water is
so shallow it can’t maintain a constant
temperature.
*(USGS. (2013, May 23). USGS: Dissolved Oxygen. Retrieved June 3, 2013, from USGS:
http://ga.water.usgs.gov/edu/dissolvedoxygen.html)
8. Biological Oxygen Demand
This test is done to show how much bacteria is
present in the water. When the sample of water for
this test was collected, it had a dissolved oxygen
level of 95%. It sat in the dark for 5 days, and when it
was tested for the second time, the level was all the
way down to 0%. This further proves how many
bacteria are in the river, and how fast the oxygen is
being used up.
9. pH
We tested the pH of the Mullet two times, and got
good results. One day was cold and pouring rain
and the other was warm and dry with no clouds.
Both tests were taken in the morning.
The sunny day we got a 7 pH. This is the best score,
meaning that it’s pure water. The organisms in the
water usually like a 7 but most can tolerate
fluctuation of the 7 to a 6 or 8. The rainy day we got
an 8 which compared with other groups stays pretty
consistent.
10. Phosphates
Both times when we took this test it resulted in a
zero, meaning there were no phosphates in the
water. However, we know that there are a bunch
entering the river. One day, we could actually see
oil on top of the water. This is an obvious sign that
there are phosphates coming in.
The reason we got zero as the outcome is because
of the bacteria again. All living things need
phosphates to survive, but there’s an extreme
amount of bacteria using it all up. This is also why it’s
hard to find other plants and animals living in the
river.*
*Riverview Science. (2013, May). Water Monitoring: Phosphatest. Retrieved June 3, 2013, from
Riverview Science:
http://hoopmanscience.pbworks.com/w/page/47827886/Water%20Monitoring%3A%20%20Phos
phates
11. Solution to the Problem
Our group believes the best approach to improving
the condition of the Mullet is to dredge it.
Dredging can help this river by getting all the mud
out. When the mud and silt is gone, the bacteria
won’t have anything to survive off of, so it won’t
come back. With the bacteria out of the river, all of
the necessary nutrients and oxygen will be able to
spread around and supply many more organisms.
Besides being able to sustain plant and animal life,
dredging will also restore the water depth to what it
originally was. The Mullet could be the recreational
hot spot that it used to be.
12. Lake Leota, Evansville
Evansville’s mill pond was in the same situation that
ours is now. Silt had piled up on the bottom, leaving
the depth no deeper than 18 inches. Their method
of restoring it was also dredging. Today, Lake Leota
in Evansville has earned back its recreational
value.*
If we take similar steps to what they’ve done to their
lake, the Mullet River will return to the state it was in
50 years ago.
*Evansville City Hall. (n.d.). Evansville: Lake Leota. Retrieved June 4, 2013, from Evansville:
Information for Residents: http://www.ci.evansville.wi.gov/residents/LakeLeota.html
13. Dredging
To dredge the river, taxes will have to be increased
to raise enough money for this process. Another
drawback is that there isn’t currently a place to put
the silt that’s removed. We could spread it in farm
fields, but that could be a concern because of the
heavy metals that are in the mud.
Over time, this mud will build up again. With slow
moving water, the organisms that die will eventually
distribute on the bottom and stay there. If we
dredge, the same steps will have to be taken in
another 50 years or so.
14. Bibliography
Evansville City Hall. (n.d.). Evansville: Lake Leota. Retrieved June 4,
2013, from Evansville: Information for Residents:
http://www.ci.evansville.wi.gov/residents/LakeLeota.html
Riverview Science. (2013, May). Water Monitoring: Phosphatest.
Retrieved June 3, 2013, from Riverview Science:
http://hoopmanscience.pbworks.com/w/page/47827886/Water%20
Monitoring%3A%20%20Phosphates
USGS. (2013, May 23). USGS: Dissolved Oxygen. Retrieved June 3,
2013, from USGS: http://ga.water.usgs.gov/edu/dissolvedoxygen.html
