EPA's Inspector General has issued a report indicating that EPA's Office of Water & state water pollution control agencies don't have in place sufficient measures to assure that states address and control nutrient pollution from reactive nitrogen and phosphorus that gets into surface waters from agriculture, municipalities and some industry across the Mississippi-Missouri River watershed system.
This is an issue with the problem of the Gulf of Mexico Hypoxic Zone off of the coast of Louisiana and portions of Texas as a result of the flow of the Mississippi and Atchafalaya Rivers into the Gulf.
In the Gulf Dead Zone, dissolved oxygen in a substantial portion of the the water column is near zero because of the presence of dying masses of algae and phytoplankton nourished by excessive nutrients in the water column, especially from reactive forms of phosphorus and nitrogen. In hypoxic zones desirable fisheries don't exist because of the lack of, or reduced concentration of, dissolved oxygen in the water column.
Many states in the basin have not adopted plans for nutrient reduction or have not adopted water quality standards for either reactive or total phosphorus and nitrogen.
The EPA IG also identified problems with adequate state water quality data and tracking information in EPA's national efforts to control nutrients.
Here is EPA report at a glance.