Meoeacish Bouldin

Casey Stevens

November 3, 2004

Research Report


The Effects of Sewage Dumping on Lake Michigan’s pH Level


In this experiment we tested the pH levels in two different areas of Lake Michigan taking five water samples from each area.  We wanted to see if there was a correlation between the pH level and the sewage dumping. Five sites from each of the two areas we looked at were tested, one area had no sewage dumping and the other area had sewage dumping.  Each site was 7.62 meters apart. We found that the areas of water that had sewage dumped in it had a lower pH and those areas of water that did not have sewage dumped in it had higher pH levels.


Keywords: Water pH, Sewage Dumping, Lake Michigan



The purpose of this experiment was to find out if the sewage dumped in Lake Michigan had an affect on the water pH level.  In order to find this out we wanted to look at areas that had sewage dumped in it and areas that did not have sewage dumped in it.  By testing different areas we would be able to see if there was a difference in the pH levels.  Our hypothesis was that the pH level would be higher in areas where there was no sewage dumping and lower in areas where there was sewage dumping.  pH levels are measured by the “hydrogen ion concentration in the water” (Vennie, 2004).   Water that has low pH levels have more hydrogen ions (H+) which means the water is acidic (Vennie, 2004).  When sewage is dumped into the water it “depletes the oxygen” (Recreational Boating and Fishing Foundation, 2001).  If oxygen is being depleted then there will be an increase in hydrogen ions (H+) in the water.  When a water molecule is separated, it separates in to a hydrogen ion (H+) and an OH- molecule (Vennie, 2004).  So if the oxygen is being depleted the OH- is being removed leaving behind the H+. 



On November 3, 2004 pH levels were tested at Lake Michigan. Five water samples were taken from two different areas of the lake using test tubes and disposable pipettes. After collecting our ten samples of water, we tested the pH levels of each sample using the LaMotte Wide Range pH Test Kit (Model P-3100, code 2117).  After adding the pH reagents to the water samples, we let it sit for about two minutes.  While doing this part of the experiment safety glasses and gloves had to be worn.  We then compared our results to the corresponding color chart included in the kit.  A measuring tape was used to measure the distance between each site, which was 7.62 meters apart.  The area we tested that would have no sewage dumping was near the beach area of Lake Michigan and the area we tested for where there would be possible sewage was near the inlet of Lake Michigan.



At site one, the pH level was 6.2, site two the pH was  4.8, site three the pH was  4.2, site four the pH was 7.2, and site five the pH was 5.6.  These were the pH levels where there was sewage dumping.  The next sites were done where there was no sewage dumping.   At site one, the pH level was 6.4, site two the pH was 7.2, site three the pH was 6.0, site four the pH  was 7.4 and site five the pH was 6.2.   Samples four with sewage dumping and sample eight with no sewage was found to have the same pH levels of 7.2.  The average pH level for the area with no sewage dumping was 6.64 and the average pH level for the area with sewage dumping was 5.6 (figure 1).   The standard deviation for the area with sewage dumping was 1.174734012 and the standard deviation for the area with no sewage dumping was .62289646.


Figure 1 pH Levels of water with Sewage Dumping and No Sewage Dumping (Average+/-Standard Deviation)



Our results support our hypothesis that water containing sewage had a lower pH than water that had no sewage. When doing a t test we got .04073499, which shows that our data was significant and our hypothesis was supported.  However we did find that one of the sites along the beach had the same pH as one of the sites we tested near the inlet.  The averages of both areas are below a pH of 7 which is considered neutral. This may be because of the mixing of the water as it moves.  It could also be due to rainfall. “Rainfall in Wisconsin varies from a pH of 4.4 in southeastern Wisconsin to nearly 5.0 in northwestern Wisconsin” (Vennie, 2004).  “Natural rainfall, exposed to CO2 in the atmosphere, maintains a pH of 5.6” (Vennie, 2004).  This could be due to human activity along the beach area of the lake.  The results indicate that there were fewer differences in pH among the samples we collected.  In the future we collect fewer samples from more areas.  We could also go to a site where sewage is actually dumped before it is treated or an area where sewage comes in at as well as maybe testing pH levels in parks or other rivers. This would allow us to see if sewage really has an effect on water. 




Vennie, James (2004). pH-acidity- Understanding Lake Data.  Wisconsin Department of

Natural Resources.  Retrieved November 1, 2004 from


Recreational Boating and Fishing Foundation (2001).  Types of Pollutants.  Water Works

Wonders. Retrieved November 1, 2004 from



National Parks Conservation Association (2004). How Acid Deposits Harm Ecosystems.

Acid rain, Sleet, Snow, Sour Soils and Streams.  Retrieved November 2004 from