EPA hereby gives notification that pursuant to its authority under Clean Air Act (the Act), section 110(k)(4), in a December 12, 1997 letter, EPA notified New Jersey that the conditional interim approval of the New Jersey 15 Percent Rate of Progress Plan had been converted to a disapproval. The letter triggered the 18-month time clock for the mandatory application of sanctions under section 179(a) of the Act and the 24-month time clock for the Federal Implementation Plan (FIP) under section 110(c)(1). This also serves to amend Title 40, part 52 to note the conversion of the conditional interim approval to a disapproval.