The threat of legal action by environmental groups is pushing the U.S. Environmental Protection Agency (EPA) to adopt strict nutrient criteria for the Mississippi River with the goal of resolving Gulf of Mexico hypoxia. The National Academy of Sciences has advised that EPA adopt numeric nutrient criteria, while many lawmakers are ready to fight more stringent requirements. While EPA administrator Lisa Jackson has said that the agency will not develop a basin-wide total maximum daily load for the Mississippi River, EPA is using a model to assess nutrient loading and dissolved oxygen issues. Scientific advisors to the agency are suggesting that EPA create interim standards for a maximum load at the river’s mouth.