Freshwater Colloquium – Agricultural Contamination in Groundwater: The Case of Nebraska
Join the School of Freshwater Sciences for a Colloquium with guest speaker: Harshanee Jayasekera, PhD
Agricultural production plays a central role in Nebraska’s economy but also poses persistent risks to groundwater quality, particularly through nitrate contamination. Because a large majority of Nebraskans rely on groundwater for drinking, understanding the effectiveness of groundwater protection policies is critical for environmental sustainability and public health in the state. I (and co-authors) examine agricultural contamination in Nebraska with a focus on evaluating the impact of policy measures such as Wellhead Protection Areas (WPAs) and the Conservation Reserve Program (CRP) on groundwater quality. Using comprehensive data from the Nebraska Groundwater Quality Clearinghouse (1996–2019), comprising over two million nitrate observations from approximately 33,000 wells, we provide evidence of statistically and economically meaningful reductions in groundwater nitrate concentrations associated with these policy interventions. Our main finding is that improvements in water quality materialize gradually, often unfolding over decades rather than years. These results underscore the importance of long-term monitoring systems and sustained policy commitment when addressing nonpoint-source agricultural pollution.
Harshanee Jayasekera is an interdisciplinary social scientist whose work focuses on groundwater quality management and long-term sustainability. Her research examines the intersection of groundwater quality and agriculture, with particular attention to how policy and management decisions shape long-term resource outcomes. Through her research and outreach, she supports evidence-based groundwater management strategies that balance agricultural productivity with environmental quality. She works extensively on groundwater sustainability issues in Nebraska, providing insights to inform decision-making at local and state levels. Her current projects examine the long-term policy implications of agricultural land retirement on nutrient pollution in Nebraska, the effectiveness of wellhead protection areas in improving groundwater quality, and the human health impacts of environmental exposures in agricultural regions.
This presentation is open to students, faculty, staff, alumni and the public.