35 Ill. Adm. Code 501.225
Animal Feeding Operation
Section 501
Section 501.225 Animal
Feeding Operation
a) A lot or facility (other than an aquatic animal production
facility) where the following conditions are met:
1) Animals have been, are, or will be stabled or confined and fed
or maintained for a total of 45 days or more in any 12-month period, and
2) Crops, vegetation, forage growth, or post-harvest residues
that are grown in place are not sustained in the normal growing season over any
portion of the lot or facility.
b) Two or more animal feeding operations under common ownership
are considered to be a single animal feeding operation if they are adjacent to
each other or if they use a common area or system to dispose of wastes.