Storms can be significant events affecting turbidity readings in a lake. A portion of the rain that falls on the land in a watershed washes into the lake as runoff. The runoff carries inorganic and organic materials, including soil, humus, chemicals, nutrients, and pollutants, into the lake. In this lesson you will explore how rain storms, watershed characteristics, and landuse affect turbidity.

As a regional landuse planner you need to prepare a report on how a rain storm affects turbidity values in a lake. The final report should take a multidisciplinary perspective. That is, it should include meteorological, landuse, and water quality factors that may influence how a rain storm affects turbidity values in a lake.

Knowledge Base
As a landuse planner you have seen data visualizations of turbidity values in lakes like the image below. Through the visualization you can see that turbidity values change, with increased turbidity at some depths on a variety of days. You know that storm runoff is only one of the possible sources for increases in turbidity measurements.

Consider your experiences with lakes after storms. What visible differences have you observed in water clarity in lakes? Do you think storm runoff affects all depths, or does it concentrate its effects at specific depths? How long does a lake appear to remain affected by a storm? How might the size of the lake’s watershed affect runoff? What other factors might relate to how a rain storm affects turbidity values in a lake?

Experimental Design
What data will you need to collect in order to prepare a report on how a rain storm affects turbidity values in a lake?

Select a WOW lake to study and use Internet resources to choose a date(s) to collect your data. (The University of Minnesota’s Climatology Working Group website at http://climate.umn.edu/climatology.htm or the NOAA National Data Center at http://www.nndc.noaa.gov/cgi-bin/nndc/buyOL-002.cgi may provide useful weather information.)

Data Collection
What format will you use to organize and record your data? When you are prepared, use the Internet to collect the data you need to complete your analysis.

Data Management and Analysis
Think about the data you have collected and how you will need to present it so that others will understand it. Should some of the data be graphed? What does your data show about how a rain storm affects turbidity values? Are there "cause and effect" relationships that appear obvious from your data?

Interpretation of Results
Describe the relationships you have found among your data. Which of the factors investigated appears to be most important related to turbidity after a rain storm?

Reporting Results
Develop a presentation based on what you have learned about rain storms and turbidity values. It can be a multi-media presentation, poster, written paper, or oral report. Include your graphs and a map of your lake showing the variety of landuses in the watershed.