“Lowest Achievable Emission Rate (LAER)” means “lowest achievable emission rate” as defined in section 171 of the Act, namely “for any source, that rate of emissions which reflects:

1. (a) The most stringent emission limitation which is contained in the implementation plan of any State for such class or category of source, unless the owner or operator of the proposed source demonstrates that such limitations are not achievable; or
2. (b) The most stringent emission limitation which is achieved in practice by such class or category of source, whichever is more stringent."

Source. #1717, eff 2-19-81; ss by #2332, eff 4-29-83; ss by #2938, eff 12-27-84; ss and moved by #5033, eff 12-27-90 (see Env-A 101.56) New. #5033, eff 12-27-90 (from Env-A 101.54); ss and moved by #6057-A, eff 6-30-95 (from Env-A 101.55); renumbered by #8256 (from Env-A 101.163), (see Revision Note #1 at chapter heading); renumbered by #8304 (see Revision Note #2 at chapter heading); renumbered by #9839 (from Env-A 101.111), (see Revision Note #3 at chapter heading); ss by #13105, eff 9-25-20 (formerly Env-A 101.113) (see Revision Note #4 at chapter heading for Env-A 100)