The Iowa Departments of Agriculture and Natural Resources and Iowa State University initially developed the Iowa Nutrient Reduction Strategy (INRS; ISU 2019a) in 2012 to provide a framework for mitigating point and nonpoint-source nutrient pollution across the state. A primary goal of the INRS is reducing total nitrogen (TN) and total phosphorus (TP) loads to Iowa streams by 45%, as established in the 2008 Gulf Hypoxia Action Plan (USEPA 2008). The INRS states that nonpoint sources contribute 92% of the TN loads that enter Iowa’s stream system each year, based on a previous statewide nutrient balance study (Libra, Wolter, and Langel 2004).
Jones, Christopher S.; Gassman, Philip W.; and Schilling, Keith E.
"The Urgent Need to Address Nutrient Imbalance Problems in Iowa’s High-Density Livestock Regions,"
Agricultural Policy Review: Vol. 2019
, Article 3.
Available at: https://lib.dr.iastate.edu/agpolicyreview/vol2019/iss3/3