A spreadsheet planning tool for assisting a state agency with cost-effective watershed scale surface water nitrogen planning

Abstract

T he Minnesota Pollution Control Agency (MPCA) is developing a statewide nutrient reduction strategy and coordinating with other states to reduce nitrogen (N) and phosphorus (P) loads in the Mississippi River. Excess N in surface waters is of concern both because of toxicity to aquatic organisms locally and because many Minnesota watersheds feed into the Mississippi River and the Gulf of Mexico, where a 45% reduction in both N and P has been proposed (USEPA Science Advisory Board 2007). Minnesota's Nutrient Reduction Strategy identifies how the state intends to achieve its first 20% reduction in N leaving the state via the Mississippi River. To provide a scientific foundation for the N reduction efforts needed in Minnesota, the MPCA worked with the University of Minnesota and US Geological Survey to characterize N loading in watersheds throughout Minnesota. Other states in the Mississippi River Watershed are engaging in similar efforts, including Iowa (Iowa Department of Agriculture and Land Stewardship et al. 2013). The University of Minnesota's role in the project included estimating nonpoint source N loads from different sources (agriculture, forestry, and urban) and pathways (runoff, drainage, and groundwater discharge); a literature review on N reduction effectiveness of various best management practices (BMPs);…