Van Pham
Zanib Bibi
Lilly Lo

Comparing the pH Levels of Lakes and Streams


We tested whether the pH concentration of rivers to lakes in Southeastern Wisconsin. We tested the pH of eight different lakes and eight different streams.Our data results showed that rivers had a higher pH level with an average of 7.5 compared to lakes in which the average pH level was 6 (p-value = 0.025).


The pH is the measurement of the hydrogen ion concentration in the water. The pH scale ranges from 1 to 14 and having a pH balance of 7 would be considered neutral. If the pH level ranges from 1 to 6, the water would be acidic and having a pH level of 8 to 14 means that the water would be basic.The concentration of hydrogen ion increases when acidic chemical compounds like (H2SO4) are added to the water because acidic compounds release hydrogen ions.The pH level decreases when basic compounds are added to the water such as NaOH.It can take hydrogen ions away from the water, therefore making the water more basic (Sharpe, 2003).

The pH balance is important because it helps to maintain aquatic ecological conditions of the water. Lower pH levels can disturbs the fish physiological system and therefore can increase the mortality rate of the fish population (Moiseenko, Sharova, 2006).

The purpose of our experiment was designed to see if there was a difference in pH levels between lakes and streams.To test this, we visited eight different lakes and eight different streams and measured their pH levels.We used pH indicator strips to measure the pH levels.We hypothesized that the pH levels of the rivers will be higher due to the streams having a constant flow, it allows the water to get replenished and rocks like limestone rocks can neutralize the acid in water.If the lakes have a higher pH level, then our hypothesis would not be supported.

Materials and Methods

We tested the pH level of lakes and streams around 11:00 a.m. - 2:00 p.m. in Southeastern Wisconsin.We chose eight lakes and eight streams to test (Table 1).††

We tested the pH levels on lakes and streams on October 4th, 11th, 18th, and 25th, 2008. At each site, we used a small disposable cup (Dixie) to obtain the water sample.We then used the pH strips to test the sample water and waited for 30 seconds.Once the strip changed color, we matched the color of the strip with the color indicator chart provided with the kit.†† At each location, we tested a total of four samples.Each sample was haphazardly taken 10 meters away from each other.Once we had a pH, we recorded our data in a chart.For all other locations, the same steps were repeated.After that we gathered all the data and calculated an average for each location.We then calculated the average for all the lakes and the average for all the streams.We then used Microsoft© Excel to evaluate and graph our data.We performed a statistical t-test (1-tailed, type 2) to get our p-value.




††††††††††† From our results, there was a significant difference in pH levels between the lakes and rivers.Our results show that the lake had a lower pH level compared to the pH level of rivers (Fig. 1, P-value = 0.025476367).Our results show that the average lake pH level (6.17) (table 1) was lower than our average pH level (7.54) of streams (see table 2).

Table: 1


Average pH

Pewakee lake


Okauchee Lake


Oconomowoc Lake


Lake Michigan


Muskego Lake


Koepmier Lake





Table: 2



Average pH

Little Menomenee river



Lincoln River



kinnickinnic River



Oak Creek River



Milwaukee River



Dale Creek









Figure 1. The average pH of Lakes and Streams


††††††††††† Our results show that our hypothesis was supported; pH levels of the streams were higher than the pH levels of the lakes.A reason why this might be is due to rain because rain is acidic.Since lakes donít have much movement, there are not many places for the acidic water to go.Streams on the other hand, tend to have a constant flow and because of this, the hydrogen ions can flow away (Beamish, 1972).Streams may be an outlet for lakes or it may come from precipitation (Sharpe, 2003).Also, if there limestone rocks are present in rivers, it could help to neutralize the acidity of the water making the pH level higher (Sharpe, 2003).

††††††††††† The low pH level is a big concern for the survival of aquatic species.††A recent study was done on aquatic species to see if the environment affected their immune system.The changing pH levels are a very important factor in freshwater species as compared to seawater species.Since sea water has a buffering capacity to resist the pH changes in the water, but fresh water species do not have that much of buffering capacity.The change in pH level of freshwater body system affects the aquatic species.The results of the study showed evidence that pH clearly changed the lysosome function of salmon (Bowden, 2008).

The other factor that could have influenced our results could be that because we all did our own separate testing of locations, we may have different viewpoints on the pH strip colors and how to determine the pH.In the future if we were to do this experiment, we may opt to do it all together so we can all agree on the pH value.We would also test nitrogen levels and temperature to see if these factor correlate or influence with pH levels.


Sharpe, S. (2003). Freshwater Aquariums.The New York Times. Retrieved on October 19th, 2008 from:

Beamish , R. (1972).Acidification of the LA Cloche mountain leakes, Ontario, and resulting fish mortalities. Journal of the fisheries research board of Canada. 29:1131-1143.Retrieved on October 12th, 2008 from ProQuest

Wisconsin Department of Natural Resources.(2008). Whatís the difference between a †††

††††††††††† lake and a river?.Retrieved November 15th, 2008 from Wisconsin Department of

††††††††††† Natural resources.Website:

Bowden, Timothy. (March, 2008).Modulation of Immune System of Fish by their

Environment.Fish & Shelf Immunology. Volume, 25.Pg, 373-383.Retrieved on 10/20/08 from ScienceDirect database.

Moiseenko, T. Sharova, O. (July, 2006). Physiological mechanisms of degradation of fish

populations in acidified water bodies.Russian Journal of Ecology 37.4. pp. 257-259. Retrieved on 10/20/08 from AcademicOnefile Database.