Several roads are closed north of Storm Lake because of an anhydrous ammonia spill.At about 5:30 Thursday afternoon, a farmer from Rembrandt pulling an anhydrous ammonia tank apparently made a turn too sharply, a pin on the tank’s running gear failed, and the tank overturned. The accident damaged the valves on the tank, causing the liquid fertilizer to be released. Emergency crews closed the roads surrounding the intersection and evacuated the area. Buena Vista County Sheriff Chuck Eddy says the Sioux City HAZMAT team allowed the nitrogen to dissipate safely and the area is being monitored for contamination.