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Air Quality Program

State Implementation Plan
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A State Implementation Plan (SIP) describes how the state implements, maintains, and enforces National Ambient Air Quality Standards (NAAQS).

A SIP is a complex collection of documents. Washington’s SIP has been developed in multiple phases over more than 30 years. This involved many stakeholders and state and local agencies. Washington’s SIP contains:

  • Rules adopted into the SIP
  • Plans for implementing new or revised NAAQS
  • Plans for attaining and maintaining NAAQS
  • State air quality programs

Ecology first submitted Washington's SIP to the U.S. Environmental Protection Agency (EPA) on January 28, 1972. Since then, we have submitted numerous revisions to EPA in accordance with the federal Clean Air Act (CAA) and its amendments. The Code of Federal Regulations (CFR 40 Part 52 Subpart WW) contains a list of the federal approvals of Washington’s SIP actions.

The SIP is continually changing. Development continues today, governed by the federal Clean Air Act.

SIP and SIP revisions

There is only one overall SIP that contains all of Washington’s rules, attainment and maintenance plans, and control strategies for areas of the state that have not met the NAAQS. Under certain circumstances, the CAA requires Washington to revise its SIP. Each time we add to, delete from, or revise something in the SIP, that action is a “SIP revision.” However, for convenience, we generally use the term “SIP” when referring to SIP revisions.

SIP Types

The scope and content of a SIP varies greatly depending on the specific area, regulatory requirements, and pollutants of concern. Some of the major types of SIPs are:

  • Infrastructure SIPs
  • Attainment plans for nonattainment areas
  • Maintenance plans for former nonattainment areas
  • Program SIPs

Infrastructure SIPs:
An infrastructure SIP shows that Washington has the legal authority, regulatory structure, and resources to implement the NAAQS in all areas of the state. Washington must develop an infrastructure SIP when EPA establishes a new NAAQS or revises an existing NAAQS.

Attainment Plans:
An attainment plan describes the measures Washington is taking to improve air quality and bring the nonattainment area into attainment with the NAAQS. Washington must prepare an attainment plan when EPA designates an area “nonattainment” for not meeting a NAAQS.

Maintenance Plans:
A maintenance plan is a major feature of a redesignation request. After a nonattainment area meets the NAAQS, Washington can request that EPA redesignate the area from nonattainment to attainment. The maintenance plan describes the actions Washington will be taking for 10 years to ensure the area will meet the NAAQs after EPA approves redesignation.

As part of the maintenance plan, the CAA requires Washington to commit to - and submit - a 10-year maintenance plan for a second 10-year maintenance period.

Program SIPs:
A program SIP implements programs or parts of programs required by the CAA. One example of a program SIP is the Motor Vehicle Inspection & Maintenance Plan, which EPA required for carbon monoxide and ozone nonattainment areas. Other examples include the Washington State Visibility Protection Program and the 1998 Smoke Management Program. See Infrastructure, Rules, and Programs SIPs for specific SIP

Rules for SIPs

Washington usually submits rules along with a SIP as enforceable means to carry out the control strategy in any type of SIP. Washington may also submit rules or rule updates by Ecology to EPA. This may be done to satisfy federal requirements, or as a state initiative to “strengthen the SIP” (improve pollution control programs).

When EPA approves a rule as part of Washington’s SIP, the rule becomes “federally enforceable.” That is, if Washington is not implementing the rule, EPA can step in and enforce the rule at the federal level. See Infrastructure, Rules, and Programs SIPs for additional details.

Who develops and approves SIPs?

Ecology is responsible for developing SIP revisions. Ecology may partner with a location clean air agency or ask the local agency to take the lead role in preparing a plan for an area in their jurisdiction.

Other organizations that may participate in SIP development are:

  • Metropolitan Planning Organizations (MPOs), which are responsible for regional transportation planning
        MPOs include Puget Sound Regional Council, Spokane Regional Transportation Council, Southwest Washington Regional Transportation Council, and Yakima Valley Conference of Governments.
  • State and local agencies, including those in neighboring states
        Some agencies that have been involved in plan development include the Washington State Department of Transportation and the Oregon Department of Environmental Quality.
  • The Western Regional Air Partnership (WRAP), which developed the technical basis for Washington’s regional haze SIP

EPA encouraged the formation of regional organizations to provide technical assistance. WRAP membership includes 14 of the 15 western states.

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