Date of Graduation

Winter 12-15-2023

Document Access

Project/Capstone - Global access

Degree Name

Master of Science in Environmental Management (MSEM)


College of Arts and Sciences


Environmental Management

First Advisor

Tracy Benning


Nitrate is one of the most common contaminants in groundwater and causes multiple health impacts when consumed. Contamination is most significant in agricultural areas and has increased steadily since the 1950s with the introduction of nitrogen fertilizers. The depth of an aquifer, sediment type, hydrogeology, redox conditions, microbe activity, fertilizer application, natural nitrogen deposits, and well construction influence the degree of nitrate contamination of an aquifer. The sources of nitrate pollution are fertilizer, manure, concentrated feeding lots, natural nitrogen deposits, atmospheric deposition, septic systems, wastewater treatment plants, and industrial activities. Nitrogen compounds applied on the surface are stored in the soil, leach into groundwater, runoff from the surface or taken up by plants. Nitrate leaches into groundwater when it dissolves in infiltrating water and percolates through the subsurface. Water infiltrates the surface during precipitation events or when irrigation water is applied. Shallow aquifers are more contaminated than deep aquifers; deeper aquifers get contaminated over a longer timeframe. This paper studies two locations in the Central Valley, California aquifer, and two locations of the High Plains aquifer in Nebraska and Texas, US. The locations have different aquifer depths, sediment types, nitrogen depositions, hydrogeology, climate, redox conditions, fertilizer application rates, and crops. These differences influence the degree of contamination of underlying aquifers. Remediation and removal of contaminants in aquifers is cost-prohibitive, and it is more effective to minimize nitrate leaching so that aquifers retain good water quality. The best practices to reduce the contamination rate are optimizing fertilizer/manure application to meet plant needs, refining irrigation timing, no-till farming, winter crops, and crop cover. Long-term studies and active monitoring can determine the effectiveness of each approach.