State Agency Comments on EPA’s Planned Nonattainment Designations For 2015 Ozone NAAQS

EPA responded to state recommendations on ozone standard attainment designations in late December 2017. In January 2018, EPA stated that it would complete the designation process by April 30, 2018. It cannot issue its final decisions prior to April 19, 2018, because EPA must notify states no later than 120 days before the final designation if EPA plans to issue a designation that modifies a state recommendation.

In their comments to EPA regarding its intent to designate certain areas as nonattainment with the 2015 Ozone Standard, the states of Indiana, Michigan, and Wisconsin all point to transport of ozone precursors (nitrogen oxides and volatile organic compounds) from northeast Illinois and points south and southeast of Lake Michigan as the main cause of ozone concentrations in excess of the standard. All three states also assert that nonattainment boundaries should be limited to areas that actually contain a three-year average ambient monitor-based design value above the standard.

Michigan and Wisconsin point to various studies of ozone formation in the Lake Michigan basin, and reference modeling studies that suggest even zeroing out emissions in certain of the EPA’s intended nonattainment areas is predicted to have little to no impact on ozone concentrations, and may even increase concentrations due to the complex chemical reactions involved in ground level ozone formation.

The State of Indiana called the inclusion of Lake and Porter counties in northwest Indiana, part of the Chicago-Naperville, IL-IN-WI Combined Statistical Area (CSA), “unjustified and unwarranted” due to the measured attainment of monitors in those counties, and the significant and permanent emission reductions that have already occurred in the area.

Michigan, like Wisconsin, commented that ozone precursor transport, and the effect of Lake Michigan are substantial issues for attainment in West Michigan. Like Wisconsin, Michigan finds a relationship between distance from the lake and ozone concentrations. However, perhaps due to its location on the eastern shore of Lake Michigan and generally prevailing westerly winds, Michigan finds that design values in excess of the standard are likely limited to about 20 miles from the eastern lakeshore, compared with Wisconsin’s finding of nominally 3 to 4 miles from the western lakeshore. As a result, Michigan has requested that EPA consider nonattainment designation for specific townships near the lakeshore, rather than full county designations.

Wisconsin is the most critical of EPA and its intention to designate certain parts of the state primarily near the western shore of Lake Michigan as nonattainment. Wisconsin argues for a state-wide designation of attainment “supported by science and data provided previously by DNR that shows that the state’s elevated ozone concentrations are the result of factors beyond the state’s control, such as out-of-state emissions, geography, and meteorology.” Short of such a determination, the state argues that any nonattainment areas should be limited to areas with measured nonattainment, essentially only areas within approximately 3 to 4 miles of the lakeshore. Monitors in Wisconsin demonstrate a strong gradient in ozone concentrations with distance from the lake. Three lakeshore counties have two or more ozone monitors, which bear out this gradient, and demonstrate that elevated levels of ozone in the state are a result of lake effect winds.

Wisconsin’s criticisms of the process include:

  • Cooperative federalism is not properly implemented
  • EPA relies far too heavily on a traditional approach to the nonattainment designation process, relying on “historical practice and outdated theories” for the Milwaukee CSA.
  • EPA fails to recognize “the science, data, and analysis provided by the state.”
  • EPA applies its reasoning for potential designations inconsistently, proposing partial county designations in certain areas, but does not sufficiently consider this same option in the Milwaukee CSA.

Wisconsin also argues for immediate revocation of the 2008 standard so that states would not be forced to implement two ozone standards concurrently, particularly given that the more recent standard is more stringent.

Currently, all of Sheboygan County is designated as nonattainment with the 2008 standard (0.075 ppm) based on the data for DNR’s monitoring site at the Kohler-Andrae State Park. That site has a design value of 0.079 ppm. This is an artifact of the traditional method used previously by EPA when it designated all of the county as nonattainment. If EPA moves forward with its previously announced intended designations for the 2015 standard (0.070 ppm), only the eastern portion of Sheboygan County (within approximately 2 to 6 miles of the lakeshore) would be designated as nonattainment for the newer, more stringent standard.  The remainder of the county would be designated as attainment based on the data from DNR’s monitoring site in Haven, which has a design value of 0.069 ppm. 

This presents an interesting and unfortunate regulatory conundrum for sources in Sheboygan Falls, Plymouth, Random Lake, and other locales in the county, more than a few miles west of Lake Michigan.  Sources there will have to deal with nonattainment area requirements under the old standard (0.075 ppm), but not for the new one (0.070 ppm).  Perhaps the state and EPA will deal with this issue but as of yet, there have not been any indications that a solution is forthcoming.

It will be interesting to see what EPA does with respect to designation decisions, the response from states, particularly for those areas that the states recommended be designated as attainment based on monitoring data, and also the response from public interest groups.  More interesting will be the development of state implementation plans, in particular for those areas where states argue that nonattainment is largely due to transport of ozone precursors from out of state.  Finally, in most areas along the eastern and western shorelines of Lake Michigan, industrial point sources are noted to be but a small fraction, generally only 10 to 20 percent, of total emissions, with the bulk of emissions coming from mobile, off-road, and other “area” sources.  Historically, the burden of emission reductions has generally fallen onto industrial sources through the new source review process and the adoption of additional emission control regulations.  Significant emission reduction opportunities through these traditional means are all but gone today.


David F. Seitz, P.E. (WI, SC)
TRC Environmental Corporation