What is a Maintenance State Implementation Plan?
There are 14 areas in Washington where we worked with local clean air agencies and communities to reduce air pollution and return those areas to meeting national air quality standards.
When an area does not meet national air quality standards, the area is classified by EPA as in "nonattainment." When an area returns to meeting national air quality standards, we ask EPA to re-classify the area as in attainment and in maintenance.
Once an area is in maintenance status, the federal Clean Air Act requires states to implement a Maintenance State Implementation Plan. A maintenance plan includes strategies to keep meeting national air quality standards in that area for 20 years.
A Maintenance State Implementation Plan includes:
- A current, comprehensive inventory of emissions.
- Enforceable measures to reduce emissions. These measures may include a combination of state, local, and federal rules, plans, administrative orders, and permits for specific sources.
- A demonstration that the measures will keep the area meeting national air quality standards for 20 years.
- Contingency measures that will be applied if the area re-violates the national air quality standards.
Washington air quality maintenance areas
The map below shows boundaries of air quality maintenance areas in Washington. The map also shows the locations of national parks and wilderness areas (also called "mandatory federal Class 1 areas," in darker green), which have special protection for visibility. Click on the map to see a pop-up window with more information, including the end date for the 20-year maintenance period and the air quality agency in charge of that area.