The Iowa Nutrient Reduction Strategy celebrated its five-year anniversary in spring 2018. In those five years, the initiative has evolved considerably, adapting as new knowledge, understanding, and challenges arose. This 2018 Annual Progress Report serves as the fifth overview of the progress that’s been made in the complex work of reducing the loads of nitrogen and phosphorus that Iowa exports to the Mississippi River. There has been clear progress in some indicators, while others represent the many challenges that remain.