The department’s annual cap on the amount of 1, 3-D pesticide that could be applied within a township was an illegal underground regulation that was not adopted, as it should have been, in compliance with the Administrative Procedure Act. Even though only one company (Dow Chemical) produced 1,3-D pesticides, the township cap program applied generally to all users of the pesticide and any other manufacturer that might in the future produce 1,3-D pesticides. And the township cap program implemented and made specific a law regulating pesticides that the Department enforced. Hence, the township cap program was an administrative regulation which was void since not adopted in compliance with the APA.