If the temperature of the hay rises to more than 140 degrees Fahrenheit, divide the hay into two piles and continue to check daily. If hay heats above 140 degrees Fahrenheit, it must be removed from a barn. Throwing or moving the hay fast may cause it to burst into flame. It is a good idea to have the local fire department standing by, or at least alerted, just in case of fire. Dry the hay until it is as dry as expected for baling.
Spontaneous combustion can occur within several weeks.
The safest management is to remove the flood-damaged hay and get it away from buildings. Flood-damaged large round bales will likely spoil excessively before they can dry again. Don't count on much usable hay from flood-damaged bales. Heating and mold growth on watersoaked bales will greatly reduce the hay's feeding value and its palatability to livestock.