Wheat and corn are the two most commonly grown crops in Kansas and Oklahoma and zones with a high risk of habitat degradation in eastern Kansas and Oklahoma correspond to areas of these and other row crops. Texas grew 6.2 million acres of cotton in 2014-15 predominately in the panhandle region, which was projected to be at high risk of fish habitat deterioration. Nutrient runoff from crop fields from all southern plains states not only affects local streams but eventually ends up in estuaries and the Gulf of Mexico. This high-nutrient runoff contributes to a low oxygen dead zone which annually averages over 5,000 square miles in size in the northern Gulf of Mexico and causes fish kills.
