Department of Natural Science
 Edgewood College
Madison, Wisconsin

Chloride Levels in and around the Lake Wingra Watershed

Background Information
We decided to test chloride levels in Madison area locations because chloride is a contaminant of lakes and drinking water. Unnaturally high chloride levels caused by road salt damages lake health. When road salt gets into the lakes the watershed is damaged. Also, chloride contamination serves as an indicator of the possible presence of other pollution that may be more difficult to detect. We tried to answer questions like: what is a healthy chloride level for lake water, and what is a healthy chloride level for drinking water? Our hypothesis was that the bodies of water with the highest amount of urban chloride levels can make it harder for some aquatic plants to grow, among other things. We believed that runoff water would have the highest level of chloride because melted snow carrying salt from the street would flow into the body of water, putting chloride into the water.

Methods
We sampled water from different ponds, springs and lakes in the Lake Wingra watershed. The sites were the Edgewood College Retention pond before rain, the Edgewood College Retention Pond after rain spring, the Sand spring, the Wheeler Spring, and HoNeeUm pond, rain barrels, Vilas Beach, tap water, de-ionized water, Marsh Water, the Middle of Lake Wingra, the mouth of the UW Arboretum spring, and the source of the UW Arboretum. We then tested the water samples to get their chloride levels. To test the chloride levels, we used the Hach Chloride Test kit. We also researched our topic on the web to see if other people came up with different answers to how much chloride was in the lake waters that we tested and some of the information was different and some of the information was the same. We also looked at Lake Monona and Lake Mendota's chloride levels. The sites we tested are listed beneath our results.

This is Kiara and Marla taking a test to see how much chloride is in this water sample.




Results
Refer to data table. We found that the Arboretum spring had the highest level of chloride (100 mg/L), the rainwater and de-ionized water tested lowest (both < 5 mg/L). Also the Edgewood College Campus detention pond tested 60 mg/L, before rain.

        Low Range Test
Date Sample # Sample Location Test # # Drops NaCl mg/L Cl mg/L Average
6/23/2003 1 Detention Pond 1 12 96 60 60
6/23/2003 2 Rain Barrels 1 1 8 5 5
6/16/2003 3 Vilas Beach 1 19 152 95 95
6/23/2003 4 Tap Water 2 18 144 90 92.5
      2 6 48 30 30
6/23/2003 5 De-ionized Water 1 1 8 5 5
6/23/2003 6 Marsh Water 1 18 144 90 90
      2 16 128 80 85
6/16/2003 7 Middle of Wingra Lake 1 14 112 70 70
6/16/2003 8 Mouth of Lake Spring 1 19 152 95 95
6/16/2003 9 Lake Spring 1 20 160 100 100
6/24/2003 10 Detention Pond After Rain 1 9 72 45 45
      2 9 72 45 45
6/24/2003 11 Sand Spring 1 9 72 45 45
      2 7 56 35 40
      3 7 56 35 38.33333
6/24/2003 12 Wheeler Spring 1 14 112 70 70
      2 15 120 75 72.5
6/24/2003 13 HoNeeUm Pond 1 14 112 70 70
      2 14 112 70 70

 

This is Hannah at the Sand Spring taking a water sample.


Discussion and Conclusions
The results we found lead us to believe that, although chloride levels vary widely at different times, the chloride levels in the Lake Wingra Watershed have risen greatly since the start of road salt use in the 1940's. We also believe that the rise in the chloride levels is unnatural and needs to be brought down. Perhaps, instead of using road salt, we could use sand or possibly chain our tires during the winter. Also, researching new options of tires with winter adaptations could help keep our community watersheds and others safe, with healthy chloride levels. We concluded that the chloride levels in the Lake Wingra watershed are higher than they initially were. In addition to that, we found out that the chloride levels vary widely among different locations. A new question that came up is how much road salt is being put onto the roads. This question is important to our study because we could determine the relationship between the amount of road salt being used and the chloride levels in the watershed.

References

  • City of Madison Inter- Department/ Correspondence: October 23rd 2001
  • Jim Lorman of Edgewood College
  • Kari Fenski of Edgewood College

 

By Kiara D. Davis, Hannah Eisen, Marla Brown, Nicole Gilbertson

 
    © 2003 Edgewood College • 1000 Edgewood College Drive • Madison, WI  53711 • http://www.edgewood.edu