Citation:

Yuan, Y. AND S. Whisenant. Water Quality Monitoring in the Lower Mississippi River Basin to Assess the Effectiveness of Agricultural Conservation Practices to Reduce Nutrient Pollution (Presentation). 2023 ASABE Annual International Meeting, Omaha, NE, July 09 - 12, 2023.

Impact/Purpose:

Water bodies and coastal areas around the world are threatened by excessive amounts of nitrogen (N) and phosphorous (P) from upstream watersheds, which can cause rapid proliferation of algae. These algal blooms negatively impact drinking water sources, aquatic species, and recreational services of water bodies by producing toxins, also called harmful algal blooms (HABs). Finding ways reducing nutrient losses from agricultural fields is paramount important for EPA program offices and regional partners to make informed decisions to better control nutrient losses from agricultural fields. 

Description:

Lake Erie is threatened by eutrophication and harmful algal blooms due to excess nutrient loading from agricultural sources. To reduce nutrient loading to Lake Erie, widespread adoption of agricultural conservation practices (ACPs) in contributing watersheds has been proposed. However, identifying appropriate and effective locations for ACP placement has been challenging. Another challenge is understanding how effective the ACPs are in reducing nutrient loading and achieving water quality goals. Therefore, identifying the most effective ACPs, as well as spatial placement of ACPs to achieve the maximum environmental benefit, is of paramount importance. A method being used to spatially identify field-scale opportunities for ACP placement across small watersheds is the Agricultural Conservation Planning Framework (ACPF), which has been recently developed by the United States Department of Agriculture (USDA) Agricultural Research Service (ARS) to aid in agricultural watershed conservation planning and management and address water quality concerns at the Hydrologic Unit Code 12 (HUC 12) watershed level. ACPF consists of a conceptual framework for agricultural watershed management; a set of Geographic Information System (GIS) tools within an ArcGIS toolbox; and a database with core input data, including field boundaries, land use, soil data, and watershed boundary data. Using a high-resolution DEM, soil, land use, and field boundaries, suitable sites are identified and mapped for a menu of ACPs and impoundments aimed at reducing nutrient and sediment loss. However, ACPF alone cannot provide estimates of the pollution load reduction provided by the various ACP opportunities and, therefore, must be combined with another method to assess the water quality impacts. The Soil and Water Assessment Tool (SWAT) (Neitsch et al., 2011b) has been developed and used extensively for hydrologic and water quality simulations at different spatial scales to assess the impact of management strategies on water quality (Arnold et al., 1999; Arnold et al., 2012, 2013; Gassman et al., 2007). The model has received extensive evaluation and validation throughout the United States and internationally (Gassman et al., 2007) and has previously been applied to evaluate the effectiveness of ACPs for water quality improvement. In this study, ACPF was used to develop ACP placement and implementation plans, and SWAT was used to evaluate the effectiveness of those implementation plans in reducing nutrient loadings from the study watershed. The integration of the two models provides new opportunities for ACP implementation to achieve the maximum environmental benefits.  

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