Development for watershed-based strategies to eliminate phosphorus related impairments in the Fox River

The Fox River in Illinois is one of 1,023 water bodies listed as impaired for water quality on Illinois’ Clean Water Act Section 303(d) list by the Illinois Environmental Protection Agency (Illinois EPA, 2021). Among these are impairments of aquatic life and aesthetic designated uses. Total phosphorus (TP) is listed as a cause of aquatic life and aesthetic impairments of the Fox River, and TP and dissolved oxygen (DO) are listed as causes of aquatic life impairments. The Fox River Study Group (FRSG) is a diverse coalition of stakeholders working together to preserve and enhance water quality in the Fox River watershed. The FRSG has undertaken a multi-phased approach to address water quality impairments in the Fox River. The approach includes multi-year monitoring of water quality and development of models to characterize the existing water quality related to the DO and TP conditions. This paper presents the application of the water quality model to evaluate the impact of management actions to eliminate the phosphorus-related impairments in the Fox River. The development of watershed-based strategies through the application of water quality models will be helpful to stakeholders in other large watersheds to address water quality impairments.