Introduction

• Local lakes and water areas are monitored throughout the year for high levels of bacteria (including E. coli) by the Madison Dane County Public Health Department
• Levels of E. coli are important because they affect those who come in contact with bacteria when swimming, boating or doing other recreational activities. Bacteria can be harmful when ingested causing intestinal illness and flu like symptoms. 
• We addressed how the levels of E. coli and coliform bacteria change in and around Lake Wingra depending on the location of the sampling and on the current weather and month in which the sampling took place. 
• We predicted that spring 1 would have the highest E. coli levels because of its location (Figure 1). We also predicted that every location’s levels of E. coli and bacteria will vary due to the season and the weather (rain, snow, etc.).

Methods

• We sampled in three different sites in and around Lake Wingra: spring 1, the end of the dock from Edgewood’s boardwalk (Dock Spring), and spring 2 (Figure 1).
• When taking our samples, we tried to make sure that there was little to no sediment in the water sample. 
• When taking a sample at the Lake Wingra Dock Spring, we tried to take samples at the same depth each time and to make sure that the sampling jar was uncontaminated until under water.
• The Colilert Test is used to determine the total amount of coliform and E. coli in water by recognizing the presence of enzymes in bacteria.  The test utilizes nutrient indicators that produce a yellowish color when coliform is present and fluorescence when E. coli is present.  The test can detect these bacteria when reagent is added to a sample and incubated for 24 hours (http://www.idexx.com/water/colilert/).

Results

• Coliform levels dropped during our last two testing dates began to rise again after February (Table 2 and Figure 2).
• Spring 1 had the highest level of E. coli out of the three sites and this occurred on December 3rd (Table 3 and Figure 3).  The levels at spring 2 and at the Lake Wingra dock were fairly consistent with each other.  The lowest levels of E. coli occurred during our first and last testing dates.
• The months of November always had the highest levels of E. coli out of the other tested months (Table 4 and Figure 4).  There were low levels of E. coli during the winter months.
• There was a decrease in temperatures from October to January in Madison, Wisconsin recorded by the Weather Channel (Figure 5).  An upward slope in temperature occurs from January to March.

Figure 1: Change in total coliform levels (MPN/100 ml) in the three different tested sites over the sampled time period

Figure 2: Change in E. Coli levels (MPN/100 ml) in the three different tested sites over the sampled time period

Figure 3: E. Coli levels (MPN/100 ml) at Lake Wingra: Dock over the past sampling years

Figure 4: Average high air temperatures (degrees Fahrenheit) in Madison, Wisconsin from October to March

Summary & Conclusions

• We had predicted that spring 1 would have the highest level of E. coli out of all three of our locations but we only found this to be true with our December 3rd sample. 
•  E. coli levels are fairly similar for each month over the past four years at the Lake Wingra Dock.  November has the highest levels of E. coli during 2005, 2007 and 2008 at the dock
•  In the months after November, the levels of E. coli drop each year mainly due to migration and the lack of animals in the area during the winter months because of the cold weather (shown in figure 5).
• Our samples show that on December 3rd at both spring 1 and spring 2, levels of E. coli were high and harmful to one’s health.
• For future studies, it would be helpful look at the temperature of the water and air during the dates sampled.  By doing this, the question as to how do levels of E. coli vary with respect to the water and air temperatures could be analyzed.

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References

• Coliform/E. coli Results in 24 Hours.  (2009).  Colilert.  Retrieved March 11, 2009 from http://www.idexx.com/water/colilert/.
•  Lorman, Jim, Edgewood College Professor

• Monthly Weather Averages and Records for Madison, WI (2009).  The Weather Channel.  Retrieved March 11, 2009 from http:www.weather.com/outlook/travel/vacationplanner/vactionclimateology/monthly/USWI0411?from=vac_dailyavg.