Abstract: At approximately 4:30 p.m. on June 5, 1996, Employee #1, a farm hand, entered a manure tower to unclog an inlet opening. The 12 ft tall by 5 ft diameter cylindrical cement structure stood in a manure pond and was fitted with several openings and a drain pipe. Manure water flows into the tower and was then pumped from it into the fields. Most of the tower was above the level of the pond, and the level of manure and water was several feet below the level of the pond. Employee #1 descended a ladder into the tower, unclogged the inlet opening, and began to climb the ladder to leave just as manure water entered the tower. He was part way up the ladder when he was overcome, presumably by methane gas, and fell to the bottom of the tower. By coincidence, the inlet clogged again at about the same time that he fell. Employee #1 unclogged the inlet, and started up the ladder. He was overcome once more and fell to the bottom of the tower, this time with his head directly in the flow of the incoming water and manure. Employee #2, one of the farm owners, entered the tower in an attempt to rescue him, but he was also overcome by the tower's atmosphere and lost consciousness. Soon members of the owner's family arrived and retrieved both Employee #1 and the owner. Employee #1 had drowned; the owner was revived and transported to the hospital.