Mitigating lake eutrophication through stakeholder-driven hydrologic modeling of agricultural conservation practices: A case study of Lake Macatawa, Michigan

Lake Macatawa is a hypereutrophic water body that connects with Michigan via navigation channel. Excess phosphorus (P) concentrations have resulted in Total Maximum Daily Load (TMDL) for total (TP) the lake, which has not been met. To guide land management and pollution control watershed, Soil Water Assessment Tool (SWAT) model scenarios of agricultural best practices (BMPs) were developed consultation stakeholders. Modelling emphasized incorporating representative local conditions. Approaches to initializing high legacy soil P levels SWAT tested. The validated was used evaluate influence BMPs on lake quality identify are necessary meeting TMDL. showed eliminating manure applications would small effect curbing TP loading, but continuous no-till residue combined already subsurface application yield notable reductions. Achieving TMDL-mandated reduction 72% possible through widespread adoption multiple (continuous residue, cover crops, filter strips, conversion some marginal croplands perennial grasses) across all watershed’s row croplands. study highlights how guidance from community interested watershed improvement integrated modeling towards addressing eutrophication informed management. case presents tractable system solutions could be transferred similar tile-drained watersheds Great Lakes basin.