SAFETY OF STREAM WATER IN WEST MOBILE, AL
Charles White, Department of Earth Sciences, University of South Alabama, Mobile, AL
36688. E-MAIL: crw604@jaguar1.usouthal.edu.
Children are known to play in and around natural and unnatural waterways. Escherichia
coli is identified by the EPA as the best indicator of health risk from water contact in recreational
waters. E. coli levels have been shown to increase with increased turbidity. The turbidity of the
streams in the area has been measured using a turbidity meter. Stream sites were determined by
ease of access and proximity to suburban neighborhoods or apartments. The streams around
West Mobile are not very turbid, although rainfall events create some variability. Turbidity does
not increase with precipitation as expected. Turbidity levels after rainfall events need to be
measured on a regular basis to find out why this happened. It is unlikely that E. coli is at
dangerous levels. This doesn’t mean that the water is completely safe. E. coli levels need to be
tested and other chemicals could be present in the water as well.
Keyword: Turbidity, Contaminants, E. coli
Introduction:
Every child at some point has played in flowing water from streams and ditches. The
purpose of this paper is to prove through turbidity measurements that the water in Mobile is clear
and safe for children.
Turbidity can be defined as the cloudiness of the water. This cloudiness is usually caused
by sediment. Higher turbidity increases water temperatures because suspended particles absorb
more heat. This, in turn, reduces the concentration of dissolved oxygen because warm water
holds less dissolved oxygen than cold water. Higher turbidity also reduces the amount of light
penetrating the water, which reduces photosynthesis and the production of dissolved oxygen.
Suspended materials can clog fish gills, reducing resistance to disease in fish, lowering growth
rates, and affecting egg and larval development. As the particles settle, they can blanket the
stream bottom, especially in slower waters, and smother fish eggs (EPA 2006). Turbid water not
only negatively affects the health of a stream, it can also indicate the levels of fecal coliforms
such as E. coli. The EPA identifies E. coli as the best indicator of health risk from water contact
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in recreational waters (EPA 2006). Fecal coliform bacteria is already known to be a problem in
the Dog River Watershed due to sewage overflows and poor septic tank maintenance.
The Chattahoochee BacteriALERT program is a partnership of the Georgia
Environmental Protection Division, the National Park Service, and the U.S. Geological Survey
(USGS) and non-governmental organizations such as the Upper Chattahoochee RiverKeeper,
Georgia Conservancy, and Trust for Public Lands. The main objective of this network is to
collect and analyze water samples for total coliform and (E. coli) bacteria. They display graphs
that indicate turbidity has a positive correlation with the presence of E. coli. This study has found
data that correlates turbidity and E. coli. Two sites along the Chattahoochee River in Tennessee
show an obvious correlation between turbidity and E. coli levels. They also show a correlation
between stream flow and turbidity. The other site on Panola Creek does not show a strong
correlation, but there doesn’t appear to be enough data available in the graph. They also found
that both total coliform and E. coli bacteria are strongly related to streamflow-adjusted river
turbidity concentration at the Chattahoochee River sites.
Several articles have found that E. coli levels and turbidity are related. “Direct and
Indirect Hydrological Controls on E. coli Concentration and Loading in Midwestern Streams” by
Vidon (2008) found that precipitation and discharge are the best indicators of E. coli
concentration. They also found that seven day precipitation totals and turbidity were the best
indicators during base flow. “Escherichia coli Loading at or Near Base Flow in a Mixed-Use
Watershed” by Gentry (2006) found that E. coli load rate was better correlated with turbidity in
the slower draining basin tailwater sampling sites than in the faster draining upstream headwater
sampling sites. In the headwater sites, the E. coli load rate was better correlated with 7-d
antecedent precipitation than turbidity.
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Eric Money (2009) in “Modern Space/Time Geostatistics using River Distances: Data
Integration of Turbidity and E. coli Measurements to Access Fecal Contamination Along the
Raritan River in New Jersey” took the research from previous articles to predict E. coli levels.
The Bayesian Maximum Entropy (BME) method of modern space/time geostatistics was used
for the data integration of monitored and predicted E. coli data to produce maps showing E. coli
concentration estimated daily across the river basin. All E. coli and turbidity monitoring data
available from existing monitoring networks for the 2000-2006 time period for the Raritan River
Basin, New Jersey was collected. Using collocated measurements, they developed a predictive
model of E. coli from turbidity data.
“Effect of Human Development on Bacteriological Water Quality in Coastal Watersheds”
by Michael A. Mallin (2000) took a different angle on determining E. coli levels. The most
important anthropogenic factor associated with fecal coliform abundance was percentage
watershed-impervious surface coverage, which consists of roofs, roads, driveways, sidewalks,
and parking lots. These surfaces serve to concentrate and convey storm-water-borne pollutants to
downstream receiving waters. Linear regression analysis indicated that percentage watershedimpervious surface area alone could explain 95% of the variability in average estuarine fecal
coliform abundance. As West Mobile has grown, this paper indicates that E. coli levels should
have grown as well.
Water quality has changed as West Mobile has developed over time. One resident of the
area voiced her concerns to me about illegal dumping and the look of the water in a local stream.
This resident has lived near one of the testing sites for 20 years and has noticed a change in water
quality. The concerns she has are the concerns we all should have. Her children used to play in
the stream at the testing site, but few parents would let there children play in it now. Other
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residents have voiced there concerns to me about the water quality, and the natural beauty of the
streams. Most of these have been concerned that I was going to dump something at the testing
sites. They, like all of us should be, are concerned with the water quality in the Dog River
Watershed.
Research Question:
What are the turbidity levels of residential streams and ditches that would be accessible to
children, and should parents be concerned with local turbidity levels? Should turbidity of the
local streams be a factor when buying or renting a house or apartment?
Methods:
The study area is a portion of West Mobile shown in the map below (Figure 1). Most of
the area is residential. It is located in the western part of the Dog River Watershed. The map also
shows the sites where
water was sampled, and
it identifies the local
streams. The site
locations were
determined using
Google Earth and field
reconnaissance. Sites
were selected based on
the amount of homes
Figure 1. Map showing the sampling locations.
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nearby and ease of access from those homes. Site one is on Bolton Branch behind the Southern
Oaks Apartment Complex. Site two in on Spencer Branch on Panorama Dr. Site three is Spring
Creek along Spring Dr. Site four is on a tributary of Spring Creek along Longleaf Dr. and
Larchmont Dr. Site five is on Milkhouse Creek at the end of Rio Vista Dr. Site six is behind an
apartment complex on Grelot Rd. along a tributary of Milkhouse Creek. Site seven is at the end
Quincy Dr. along a tributary of Second Creek. Site eight is located at the corner of Creekwood
Place Dr. and Charlanda Blvd. on a tributary of Second Creek. Photos of the sample sites are
located in Appendix 1.
Water samples were taken March 4th, March 11th, March 23rd, April 1st, and April 8th. The
samples were kept in a refrigerator after they were taken. The first three samples were allowed to
reach room temperature before they were tested using a Turbidity meter on March 25th. Samples
were tested 5 consecutive times, and the median value in NTUs was used for the results. This
process was repeated for the last two samples on April 8th.
Results:
The average turbidity for all of the sites over the sampling period was 2.87 NTU. Table 1
shows the turbidity data for the sites including averages for sample sites and testing days. Figure
2 shows the average turbidity over the testing dates. Test site 8 shows no data for April 1st and
April 8th because the site was on private property that changed ownership. The new owners were
not available to get permission. The data shows increases of turbidity in most of the sites on
March 11th and April 8th. These tests followed rainfall events. The USA Mesonet data for the
Center for Hurricane Intensity and Landfall Investigation has two rainfall gauges. These gauges
read .659 inches and .610 inches on March 11th. The gauges read .285 inches and .295 inches on
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April 8th. There was little to know rainfall the day before. Significant precipitation did not fall
preceding the other test dates.
Table 1. Turbidity measurements in NTUs.
Site Number
1
2
3
4
5
6
7
8
Average
3/4
0.71
0.95
1.44
0.52
2.14
1.06
1.50
0.74
1.13
3/11
1.18
1.98
2.86
1.02
2.58
6.70
2.39
1.74
2.56
3/23
1.43
1.23
1.81
0.61
3.13
2.18
2.95
1.32
1.83
4/1
0.75
1.29
0.64
1.66
0.89
0.96
0.90
N/A
1.01
4/8
4.56
6.34
6.33
2.00
4.81
19.80
14.00
N/A
8.26
Average
1.73
2.36
2.62
1.16
2.71
6.14
4.35
1.27
2.87
Figure 2. Graph showing changes in average turbidity by sampling date.
Turbidity measurements were highest on April 8th. On this day the water at all of the
streams sites appeared to be darker than normal. It appeared almost black in some spots. Figure 3
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shows side by side photos at site 7. It is not clear exactly what caused this, but it is something to
be considered. The other testing day following a rain event did not show results as dramatic.
Figure 3. The left photo was taken April 13th, and the right photo was taken April 8th.
Conclusion:
Turbidity data of the stream sites tested in West Mobile indicate that water E. coli levels
are not a major problem in this part of the Dog River Watershed. Although E. coli levels are
likely not a major problem in this area of the watershed, turbidity measurement did get rather
high one day. The highest turbidity measurements came after the less significant rainfall event.
Children should not be allowed to play in streams with a 20 NTU turbidity measurement. Since
rainfall amounts did not indicate turbidity levels it would be best to check the water first after a
rainfall event. At least at this point in time, turbidity of the local streams does not seem to vary
enough in West Mobile to be a deciding factor in residency.
Although turbidity of streams in West Mobile indicates that they are safe for our children,
the streams can be noticeably polluted and dirty. Illegal dumping is a problem in West Mobile.
Residents living near these test sites have seen the stream’s quality deteriorate over time. If these
streams are to be saved for future generations to enjoy, attitudes will have to change. Just as
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people directly adjacent to these streams show concern, other residents did not. Some of the
residents I talked to had no concern over what I was doing or the health of the streams.
One thing that needs to be done is a measurement of turbidity along with E. coli or other
harmful substance to show there is a correlation in the streams around Mobile. This project could
be expanded to other parts of town. It would be beneficial to know if socio-economic status
correlates with turbidity. This project has shown that children can still play in the streams of
West Mobile, but it is definitely not as pleasant as it used to be.
Bibliography
E. Money, G. Carter, and M. Serre. 2009. "Modern Space/Time Geostatistics Using River
Distances: Data Integration of Turbidity and E. coli Measurements to Assess Fecal
Contamination Along the Raritan River in New Jersey." Environmental Science &
Technology 43, no 10: 3736-3742. http://web.ebscohost.com.libproxy2.usouth al.edu
(accessed February 26, 2010).
P. Vidon, L. P. Tedesco, J. Wilson, M. A. Campbell, L. R. Casey, and M. Gray. 2008. "Direct
and Indirect Hydrological Controls on E. coli Concentration and Loading in Midwestern
Streams." Journal of Environmental Quality 37, 1761-1768.
http://jeq.scijournals.org/cgi/reprint/37/5/1761 (accessed February 26, 2010).
Randall W. Gentry, John McCarthy, Alice Layton, Larry D. McKay, Dan Williams, Shesh R.
Koirala and Gary S. Sayler. 2006. “Escherichia coli Loading at or Near Base Flow in a
Mixed-Use Watershed.” Journal of Environmental Quality 35, 2244-2249.
http://jeq.scijournals.org/cgi/content/full/35/6/2244 (accessed March 20, 2010).
U. S. Geological Survey. 2002. "Chattahoochee BacteriALERT: Background." Georgia
Riverway Project. http://ga2.er.usgs.gov/bacteria/SummaryResults Turbidity.cfm
(accessed February 26, 2010).
Mississippi-Alabama Sea Grant Consortium. 1999. "Dog River Watershed."
www.masgc.org/pdf/masgp/99-011.pdf (accessed February 26, 2010).
Environmental Protection Agency. 2006. “Monitoring and Accessing Water Quality.” 5.5
Turbidity. http://www.epa.gov/volunteer/stream/vms55.html (accessed February 26,
2010).
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Environmental Protection Agency. 2006. “Monitoring and Accessing Water Quality.” 5.11 Fecal
Bacteria. http://www.epa.gov/owow/monitoring/volunteer/stream/vms511. html
(accessed February 26, 2010).
Michael A. Mallin, Kathleen E. Williams, E. Cartier Esham, R. Patrick Lowe (2000) “Effect of
Human Development on Bacteriological Water Quality in Coastal
Watersheds.”Ecological Applications 10, no 4: 1047-1056. http://web.ebscohost.
com.libproxy2.usouthal.edu/ehost/detail?vid=4&hid= 13&sid=470c2086-0f30-4ba181fb-158307e70aa6@sessionmgr11 (accessed March 20, 2010).
National Oceanic and Atmospheric Administration. “University of South Alabama Center for
Hurricane Intensity and Landfall Investigation.” http://chiliweb.southalabama.edu/
index.php (accessed May 2, 2010).
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Appendix 1
Site 1
Site 2
Site 3
Site 4
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Site 5
Site 6
Site 7
Site 8
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