Dissertations and Theses @ UNI


Open Access Thesis


Algal blooms--Iowa; Agricultural pollution--Environmental aspects--Iowa;


Insuring the safety of our water for consumption and recreation is a crucial but extremely difficult and resource intensive activity of environmental protection agencies. One of the ways our water is at risk is through the increased frequency, and intensity of harmful algal blooms (HABs). When CyanoHABs occur, they can produce a toxic byproduct, most notably microcystin in freshwater, which can be harmful to humans and animals. Previous research has indicated these blooms are driven by increased eutrophication of water bodies, the excess loading of nutrients. In Iowa, the main driver of CyanoHABs in most watersheds is agricultural runoff, which carries increased nutrient loads from fertilizer, sediment, and animal waste. CyanoHABs can be further enhanced by a range of climatic conditions that potentially serve as drivers (e.g. air temperature and precipitation). Although there has been research into the spatio-temporal drivers, further research is needed to better explain how and when blooms occur in relation to different land use and climatic factors, or ultimately how we can predict CyanoHABs. This research uses PRISM climate data, land use/cover data from the USDA, and water quality data from the Iowa State Department of Natural Resources as dependent and independent variables in statistical regressions to determine land use/climate associations with CyanoHABs and to determine if a predictive statistical model can be developed to predict future CyanoHABs. This research spans from 2006-2016 and lakes included in the Iowa State Beach Monitoring Program. Logistic and multiple linear regressions were performed for all variables to identify the main drivers of harmful algal blooms and increased concentrations of microcystin. A logistic regression produced an RP 2 P = 0.44, with the main predictors being turbidity, soil moisture 2 weeks prior, and cooler/wetter spring and winter seasons. Multiple linear regression showed that higher temperatures 3 weeks prior could increase the concentrations of microcystin, as well as higher temperatures the day of sampling, increased turbidity, and the total length of streams within the watershed of the sampled lake.

Year of Submission


Degree Name

Master of Arts


Department of Geography

First Advisor

James Dietrich, Chair, Thesis Committee

Date Original


Object Description

1 PDF file (viii, 74 pages)



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