Approval and Promulgation of State Implementation Plans: Washington

The Environmental Protection Agency (EPA) is approving revisions to the Washington State Implementation Plan (SIP) for particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM10) for the Yakima, Washington nonattainment area. On March 24, 1989, the Washington Department of Ecology (WDOE) submitted a plan for attaining and maintaining the National Ambient Air Quality Standard (NAAQS) for PM10 in the Yakima PM10 moderate nonattainment area and the plan was amended with additional submittals between 1992 and 1995. EPA proposed to approve and disapprove portions of the SIP submitted by the state of Washington on November 7, 1995. Subsequent to the November, 1995 proposal, EPA received two additional revisions from WDOE, dated November 3, and December 27, 1995 that resolved EPA's concerns in the proposed disapproval of portions of the Yakima PM10 nonattainment plan. Although EPA promulgated a new PM NAAQS, which became effective on September 16, 1997, the requirements which are the subject of this document arise under the pre-existing PM NAAQS.