Of the 12 agricultural states in the Mississippi-Atchafalaya River Basin, only Ohio and Iowa have plans to reduce the amount of nitrogen and phosphorus that enters waterways, according to a report from the inspector general. Runoff from agriculture, industry and household items such as detergents contribute to high phosphorus levels, making it a hard-to-regulate problem. States along the Mississippi are of particular concern, due to their ability to contribute to the gulf dead zone, an area with low oxygen that threatens marine life.