During July 1995, a poultry waste lagoon ruptured in Duplin County, North Carolina, sending 32.6 million L of chicken waste effluent into a nearby creek and the Northeast Cape Fear River. In August 1995 a breach of a hog waste lagoon released approximately 7.6 million L of waste into a system of blackwater creeks in Brunswick County, North Carolina. The poultry waste spill occurred under high rainfall‐high river flow conditions, while the swine waste lagoon spill occurred during dry conditions. Both spills caused high turbidity and low dissolved oxygen (DO) in receiving waters, and DO levels in the Northeast Cape Fear River displayed a “sag curve” 10 d after the poultry waste spill, reaching a minimum of 1.0 mg L−1 90 km downstream. Both spills delivered high N loads to receiving waters (maxima of 92.1 mg L−1 from the poultry spill and 47.0 mg L−1 from the swine waste spill). Phosphorous concentrations reached 6.0 and 11.5 mg L−1 in receiving waters of the poultry and swine waste spills, respectively. Dense phytoplankton blooms (>100 µg chlorophyll a L−1) were measured in the blackwater creeks after the swine spill. High fecal coliform concentrations were delivered by both spills, and concentrations of the pathogenic bacterium Clostridium perfringens ranged up to 40 000 colony‐forming units (CFU) mL−1 in the receiving waters after the poultry spill. In 1995 and 1996 more than 30 animal waste lagoon breaches, overtoppings, and inundations were reported in North Carolina, demonstrating the major pollution potential of these treatment systems.