Meghan McLeod, Nandita Basu, Kimberly Van Meter (2022). Nitrogen Legacies in the Transboundary Lake Erie Basin. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

Lake Erie is a source of drinking water, recreation, and commercial opportunity in the U.S and Canada, making the protection of its water quality essential. In the past decades, Lake Erie's ecosystems have been adversely impacted by recurring toxic algal blooms. These algal blooms are attributed to nitrogen (N) and phosphorus pollution from agricultural activities. Despite recent efforts to reduce N application in the Lake Erie basin, high levels of N concentration persist in surface and groundwater systems. One of the reasons for this apparent stasis in N concentrations is legacy stores of N in landscapes that contribute to lag times in water quality response, even after inputs have ceased. Legacy N is stored in the soil and slow-moving groundwater and makes up a large portion of current N contamination. Quantifying these available legacy N stores is essential for creating nutrient reduction targets. My project aims to quantify N legacies across the entire Lake Erie basin to predict time lags in water quality improvements. To do this, we use a process-based modelling framework, ELEMeNT, to quantify legacy N stores and watershed-scale N dynamics over the past century in multiple sub-watersheds across the basin. Our model results will inform nutrient management practices across the Lake Erie basin by explicitly incorporating legacy dynamics. These proposed management strategies will, ideally, lead to improved water quality across the Lake Erie basin.

AOSM2022 Lake Futures First Author: Meghan McLeod, University of Waterloo Additional Authors: Dr. Nandita Basu, University of Waterloo ; Dr. Kimberly Van Meter, Penn State University