The Mississippi River Basin Phosphorus Problem: Past History and Future Challenges to Solve It

In 1997, the EPA created the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force which is commonly known as the hypoxia task force (HTF) to address the growing dead zone problem in the Gulf of Mexico caused by nitrogen and phosphorus. The HTF developed an Action Plan in 2001 to address the issue but little progress was made on the problem, so they developed another one in 2008. The 2008 plan as a first step called for all states in the Mississippi/Atchafalaya River Basin to complete and implement comprehensive nutrient reduction strategies for all watersheds with significant contributions of nutrients to the surface waters in the Basin. All states have developed nutrient reduction strategy plans and have started implementing them. A research study in 2011 which used models to examine phosphorus loading from all 1,768 counties in the Mississippi River Basin found there was little relationship between livestock manure and water quality and, in crop production areas found farmers removed more phosphorus in harvested crops than what they applied in fertilizer, suggesting that overzealous fertilizer use is not the issue. Soil erosion and tile drainage are among the major contributors of phosphorus to the Mississippi and Gulf of Mexico each year. Sewage treatment plants in Chicago and other major metropolitan areas “showed up as hot spots”, because most municipalities don’ t remove phosphorus. Starting in the 1990s there has been a major research effort to evaluate crop production practices and water quality relationships and best management practices to reduce phosphorus loading. Some of the major findings are summarized and discussed in the paper.