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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Water Quality and Ecology Research » Research » Publications at this Location » Publication #407301
Research Project: Enhancing Long-Term Agroecosystem Sustainability of Water and Soil Resources Through Science and Technology

Location: Water Quality and Ecology Research

Title: Effects of flood conditions on lake water quality in an agricultural watershed with multiple conservation practices

Author
item Lizotte Jr, Richard
item Heintzman, Lucas
item Witthaus, Lindsey
item Locke, Martin
item Moore, Matthew

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2025
Publication Date: 1/20/2025
Citation: Lizotte Jr, R.E., Heintzman, L.J., Witthaus, L.M., Locke, M.A., Moore, M.T. 2025. Effects of flood conditions on lake water quality in an agricultural watershed with multiple conservation practices. Agrosystems, Geosciences & Environment. 8:e70046. https://doi.org/10.1002/agg2.70046.
DOI: https://doi.org/10.1002/agg2.70046

Interpretive Summary: This study measured surface water quality (WQ) in a 625 ha Conservation Effects Assessment Project (CEAP) watershed, Beasley Lake, in Mississippi, under varying flooding conditions from 2008 to 2022. Flooding impacts were determined by measuring lake water quality before and after flood events during minor flooding (99 ha flooded), moderate flooding (235 ha flooded), and major flooding (332 ha flooded). During minor flooding, only lake nitrite nitrogen increased 82%. During moderate flooding, lake dissolved solids decreased 21%,, suspended solids increased 259%, and most nutrients increased from 33-199%. During major flooding, lake dissolved solids decreased 22%, suspended solids increased 237%, and phosphorus increased 25-164%. Results showed that greater flooding increased lake suspended solids and nutrients.

Technical Abstract: This study measured 17 surface water quality (WQ) parameters in a 731 ha Conservation Effects Assessment Project watershed, Beasley Lake, in Mississippi, under varying flooding conditions from 2008 to 2022. To assess flooding impacts on lake WQ, data from before and after flood events were compared among three floodstage categories: minor flooding at 30.95 m mean sea level (MSL), 99.1 ha of the watershed inundated affecting 27.9 ha under conservation practices (CPs); moderate flooding at 32.17 m MSL, 235.1 ha of the watershed inundated affecting 69.2 ha under CPs; and major flooding at 32.78 mMSL, 331.8 ha of the watershed inundated affecting 87.0 ha under CPs. During minor flood events, only nitrite significantly increased (82%; p < 0.05) from pre- to post-flood conditions. For moderate flood events, dissolved solids decreased 21%, whereas suspended solids increased 259%, and most nutrients increased from 33% to 199% (ammonium) except nitrate and N:P ratios.With major flooding, dissolved solids also decreased 22% and suspended solids increased 237%, with increased phosphorus from 25% to 164% (orthophosphate) and decreased N:P (36%). Correlation analysis showed greater flood duration (in days) and magnitude (as river stage) increased suspended solids and nutrient concentrations. Weaker relationships were observed with watershed and CP area inundation and WQ. Results will provide landowners and action agencies with predictive changes in WQ parameters based on flooding stage and potential impositions of effects through watershed areas that coincide with CPs.