Modeling TMDLs in the Minnesota River Basin

Project Staff: 

Principal Investigators: David Mulla, Professor, Department of Soil, Water and Climate; Mary Renwick, Senior Fellow, Water Resources Center; James Anderson, WRC Co-Director and Professor, Department of Soil, Water, and Climate, University of Minnesota

Additional Staff: Prasanna Gowda, Senior Research Associate, Department of Soil, Water, and Climate, University of Minnesota


U.S. Department of Agriculture Section 406 Integrated Water Quality Program

Project Duration: 

March 2001 - June 2001


Nonpoint source pollution is a serious problem in southern Minnesota, especially the Minnesota River Basin. The major sources of concern include sediment, phosphorus, and nitrogen. Total Maximum Daily Loads are being established by the Minnesota Pollution Control Agency (MPCA) to evaluate existing pollutant loads and their sources and to propose load reductions that are economically feasible and environmentally beneficial. One of the difficulties in establishing TMDLs is the paucity of water quality monitoring data and the absence of significant research pertaining to the sources of water quality impairment. For example, it is often difficult to separate the phosphorus contributions to water quality monitoring data of fertilizer from those of manure, septic systems, and wastewater treatment plants. Similarly, it is very difficult to estimate how much of a reduction in pollutant loads is possible using various conservation practices and best management practices (BMPs). A related issue is the financial and economic implications of alternative BMPs and their distributional implications for different types of agricultural producers. One approach to overcoming these three challenges is to combine limited water quality monitoring data with water quality modeling efforts and economic analysis of BMPs.

In this project, the Agricultural Drainage and Pesticide Transport (ADAPT) model was used to investigate the existing loads, sources, and load reductions possible for agricultural landscapes typical of the Upper Midwest for alternative BMPs, focusing primarily on nutrient and tillage practices. The economic effects of these practices were estimated for various types of producers based on cropping system, size of operation and land ownership status. The analysis focused on the Bevens and Sand Creek watersheds. Research results indicate that many of BMPs examined increase profits while achieving environmental improvements.