Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Chansheng He

Second Advisor

Dr. James Biles

Third Advisor

Dr. Kathleen Baker

Access Setting

Masters Thesis-Open Access


The purpose of this research was to identify the primary variables that lead to high nitrate levels in Dodge County, Wisconsin. Trend surface analysis was used to identify which land use/land cover and aquifer characteristics are responsible for increased nitrate levels. A kriging model with residuals from the trend surface analysis, were then applied to estimate the spatial distribution of nitrate levels in the entire study area. Cross-validation was conducted to assess the uncertainty of the kriging model in the analysis.

The result from the trend surface analysis showed that, soil depth to bedrock, agriculture, urban, barren and shrub land, Y squared coordinate, depth of well, Y coordinate, and soil hydrologic group AD all had a significant relationship to nitrate levels. The kriging model showed that there are three areas of high nitrate levels in Dodge County, Wisconsin. The Pearson's correlation shows that the estimated and observed nitrate levels were highly correlated (r = 0.932). Areas of high, medium, and low risk for nitrate contamination were then identified in Dodge County. The results indicated that only the northern 16 percent of the county had nitrate levels in the medium and high risk categories. These areas should be targeted for water quality management.

Included in

Geography Commons