**Clean Air Corridor Emissions Tracking System**

The preamble of the RHR defines a CAC as "a region that generall y brings clean air to a receptor region", and also say s, "the requirement to track emissions will enable states to quickly determine if changes in patterns of emissions will reduce the number of clean air day s (defined as the average of the 20% clearest day s) in an y of the 16 Class I areas." The actual requirements state that the §309 SI P or TI P must describe and provide for implementation of compr ehensive emission tracking strategies for CAC to ensure that the visibility does not degrade on the least

impaired day s at an y of the 16 Class Iareas. Using the most recent emission inventory data available through the Emissions Data Management S ys tem (E DMS), WRAP will produce a report for each five

- ye ar implementation plan revision (2007

- 8, 2013, and 2018) on the current and projected emissions in the CAC and in areas surrounding the corridor and compare these emissions to a 1996 baseline, as part of a l arger source apportionment exercise managed b y the Technical Oversight Committee (described in the next section). The EDMS will have the capability to produce the following special reports in tabular and simple plots (i.e., bar graph and pie chart) format s and allow queries of the same information including presentation in GI S format, in addition to the standard reports:

 A summary

report of the annual summed total emissions for all six source categories and all of the pollutants by

county /state and tribal lands, as well as for the entire CAC.

 A summary

report of the annual summed total emissions for all six source categories and all of the pollutants for the same t ypes of political boundaries surrounding the CAC.

 A summary

report of the comparison of the annual summed total emissions for all six source categories and all of the pollutants for the same ty pes of political boundaries, as well as the entire CAC and the corresponding base y ear total emissions. The EDMS to be developed is described in a draft te chnical report to the Emissions Forum: Needs Assessment for Evaluation and Design of an Emissions Data Reporting, Management, and Tracking S ys tem , (EA Engineering, Science, and Technology , June 26, 2003). As part of the next round of anal ys is and preparation for regional haze SI Ps due in 2007

- 08, the Technical Oversight Committee will be conducting two separate visibility source apportionment exercises (described in the WRAP 2003

- 08 Strategic Plan), integrating analy tical results from aerosol and meteorol ogical monitoring, air quality modeling, and preparation of emissions inventories. These source apportionment exercises will identify the source regions and categories causing visibility impairment at Class I areas. As part of those source apportionment exercises, the TOC will analyze the changes in emissions for the counties and tribal lands in the CAC, as well as those surrounding the CAC. Better emissions inventory data is expected to be available each time, as the TOC iterates through these 2 exercis es. Specific results from each of the source apportionment exercises will address emissions growth both inside and surrounding the CAC, as well as the impact on visibility at affected Class I areas.