1. a) An Animal Feeding Operation is defined as a Medium CAFO if the following numbers of animals specified in any of the following categories are stabled or confined and subsection (b), (c) or (d) is met:

   Number of Animals	Kind of Animals
   200 to 699	Mature dairy cows, whether milked or dry
   300 to 999	Veal calves
   300 to 999	Cattle other than mature dairy cows or veal calves. Cattle includes heifers, steers, bulls, and cow/calf pairs.
   750 to 2,499	Swine, each weighing 55 pounds or more
   3,000 to 9,999	Swine, each weighing less than 55 pounds
   150 to 499	Horses
   3,000 to 9,999	Sheep or lambs
   16,500 to 54,999	Turkeys
   9,000 to 29,999	Laying hens or broilers, if the Animal Feeding Operation uses a liquid manure handling system
   37,500 to 124,999	Chickens (other than laying hens), if the Animal Feeding Operation uses other than a liquid manure handling system
   25,000 to 81,999	Laying hens, if the Animal Feeding Operation uses other than a liquid manure handling system
   10,000 to 29,999	Ducks, if the Animal Feeding Operation uses other than a liquid manure handling system
   1,500 to 4,999	Ducks, if the Animal Feeding Operation uses a liquid manure handling system

2. b) Pollutants are discharged into the waters of the United States through a human-made ditch, flushing system, or similar human-made device;
3. c) Pollutants are discharged directly into the waters of the United States that originate outside of and pass over, across, through, or otherwise come into direct contact with the animals confined in the operation; or
4. d) The Agency designates the Animal Feeding Operation as a CAFO under Section 502.106.

(Source: Amended at 48 Ill. Reg. 3196, effective February 15, 2024)