Minnesota State Implementation Plan (SIP)


Fawkes Char, 651-757-2327; or Maggie Wenger, 651-757-2007

Questions and answers

The goal of the federal Clean Air Act (CAA) is to ensure that human health and the environment are protected from the adverse effects of air pollution. Through the CAA, the U.S. Environmental Protection Agency (EPA) limits air pollution by setting standards. This includes standards for how much of certain pollutants can be in the air, along with standards for how much air pollution specific sources can emit.

The CAA places much of the responsibility for preventing and controlling air pollution on the states. In order for a state to administer certain air quality programs, the state must adopt a plan and have it approval by EPA. The federal review and approval process provides for some consistency among state programs and ensures that each complies with the requirements of the CAA and EPA rules.

The vehicle for demonstrating compliance with the CAA and EPA rules is the State Implementation Plan (SIP), which is established as part of Title I, Section 110 of the CAA. A SIP adopted by the state and approved by the EPA is legally binding under both state and federal law, and may be enforced by authorities at either level.

The SIP focuses on regulation of the criteria air pollutants, which are those pollutants for which EPA has set a National Ambient Air Quality Standard (NAAQS) to protect human health. Air toxics, or hazardous air pollutants, are regulated under other portions of the CAA and are not included in the SIP.

The EPA can also require states to submit SIPs to meet air quality goals other than the NAAQS, such as SIPs that have been required for regional haze.

Other CAA programs also require states to design an implementation plan and submit that plan to EPA for approval. However, these are not considered SIPs. Examples of such plans include the state Title V operating permit program and programs (such as 111(d) plans) to deal with hazardous air pollutants. Since these plans do not specifically relate to criteria pollutants, they are not part of the SIP. However, the EPA has approved some of Minnesota’s operating permit program rules into the SIP.

The six criteria pollutants are: carbon monoxide (CO), sulfur dioxide (SO2), ozone (O3), nitrogen dioxide (NO2), lead, and particulate matter in two size fractions: less than 10 microns (PM10) and less than 2.5 microns (PM2.5). Primary and secondary NAAQS are established for each of these pollutants. Primary standards define the air quality required to prevent adverse impacts on human health while secondary standards define the air quality required to prevent adverse impact on other elements of the environment such as vegetation. The main objective of the SIP process is to ensure that all areas of the country meet the NAAQS – known as being in “attainment” with the standards. Areas with air quality that is worse than a standard are in “nonattainment.”

A listing of the current health-based primary NAAQS standards can be found on EPA’s website

The NAAQS are not static. EPA must review each standard every five years, in order to ensure that each standard continues to provide adequate protection of human health and the environment. Recent reviews have resulted in revision of many of the standards, making them more stringent.

When EPA revises a standard, states must evaluate their air quality data to determine if they attain the new standard. States then must make a designation recommendation to EPA, describing whether areas are in attainment or nonattainment. EPA sets forth guidelines for making designation recommendations and the data to be used, which include both monitoring and modeling data. For nonattainment areas, the state must recommend a specific geographic area to be the “nonattainment area.”, By definition, nonattainment areas must contain the ambient air that exceeds the standard along with all the sources that contribute to the nonattainment. The final designation of an area’s status as attainment or nonattainment is made by the EPA, and is published in the Federal Register.

In attainment areas, where the ambient air meets the NAAQS, the state must demonstrate that it has sufficient authority in its SIP (generally through air quality rules) to control air pollution and ensure that the area continues to maintain the NAAQS.

If all or part of a state is designated as being in nonattainment, the state must submit a SIP revision including the measures that the state will take to return to attainment.   Monitoring and modeling data are used to determine the specific sources or source categories that are important contributors to the nonattainment.

The SIP then includes permanent, enforceable limits and controls on sources that contribute to the nonattainment, accomplished through rules or site-specific limits in an Administrative Order or permit. The plan also must include a demonstration, usually using air quality modeling, that the controls included in the plan will be sufficient to bring the area back into attainment by a date specified by EPA.

Minnesota’s original nonattainment areas were determined by which air quality control monitors showed a violation of a particular criteria pollutant standard. Then an area surrounding the monitor, including all potentially significant contributors to that violation, was delineated as the nonattainment area. Generally, the potentially significant contributors to each nonattainment area are identified by determining which sources (both point and area) emit a significant amount of the pollutant of concern. These sources are termed culpable sources. This data is obtained from an emissions inventory of each potential source in the area. Culpable sources can also be determined through the use of air quality modeling, to determine what sources have an impact on the area that is exceeding the standard. Occasionally, other methods such as receptor modeling are used to determine potentially significant contributors. The distance and direction of the potential source from the monitor with the violation is also considered.

The contents of a SIP can be considered in two broad categories; both become federally enforceable once approved by EPA as part of the SIP.

  • site- or area-specific plans and documents
  • state rules or statutes and programs. 

Any site-specific plan or rule that the state or EPA believes is necessary to attain and maintain the NAAQS should be included in the SIP. A state may independently request to include a plan or rule in the SIP, or EPA may require a state to include certain rules and plans in its SIP. For instance, EPA’s recent revisions to the fine particle (PM2.5) and ozone NAAQS will require states with nonattainment areas to write and submit SIPs to attain those standards, and for other areas to demonstrate that their SIPs contain appropriate measures to allow them to maintain the standards.

If a state fails to meet an EPA deadline for SIP submittal, or does not include an EPA mandated item in its SIP, the state may be subject to a Federal Implementation Plan (FIP). Under a FIP, EPA determines what steps are necessary within the state to meet the NAAQS or other requirements.

Originally, MPCA imposed site-specific conditions through issuing an Administrative Order (Order) to each of the culpable sources. These Orders were similar to the MPCA’s early (pre-Title V) air quality permits except that they regulated only one pollutant and did not expire. Currently, the MPCA’s preferred practice is to place federally-enforceable limits in a facility’s Title V or state permit. This ensures that all the applicable requirements for a facility are contained in a single document. Each limit that is established under Minnesota’s Title I SIP authority is noted in the permit as a “Title I Condition: SIP for (pollutant name) NAAQS,” clearly marking it as a SIP requirement. Title I conditions never expire, regardless of the overall status of the permit, allowing them to meet federal requirements for the permanence of SIP conditions. The enforceable document is then referred to as the joint Title I/Title V or joint Title I/permit document, because Minnesota is establishing SIP limits through its Title I authority and issuing a permit through its Title V or permitting authority.

If limits or conditions are needed on a variety of sources, the MPCA would also consider rules to implement limits needed for the SIP.

One important aspect of the SIP is that states are required to have a New Source Review (NSR) permitting program, known as Nonattainment New Source Review (NA NSR) in nonattainment areas and Prevention of Significant Deterioration (PSD) in attainment or maintenance areas. These permitting programs apply to new and modifying major sources and are designed to ensure that NAAQS are protected. States can have a SIP-approved NSR program, operated under their own rules but meeting minimum federal requirements, or operate a delegated NSR program by following the federal rules.

Minnesota operates SIP-approved programs for both PSD and NA NSR.

For more information, see the MPCA’s NSR webpage.

Once an area is officially designated as a nonattainment area by EPA, some specific requirements come into play. The first is nonattainment New Source Review (NA NSR) permitting for new or expanding facilities, including requirements for offsets. Minnesota’s Offset rule or NA NSR program became federally enforceable on May 31, 1994. The rule is found at Minn. R. 7007.4000 - 7007.4030 and essentially incorporates by reference 40 CFR § 51, Appendix S, with some exceptions. This EPA approval means that the MPCA operates a SIP-approved NA NSR program in nonattainment areas.

The Offset rule applies to new major sources or major modifications in nonattainment areas (for the pollutant that the area is designated nonattainment), or new major sources or major modifications that would contribute to a violation of the NAAQS in a nonattainment area. For clarity, if a facility located in a SO2 nonattainment area wanted to do a major modification for PM10, the facility would not be subject to the Offset rule.

New sources wanting to locate in a nonattainment area must go through NA NSR if they have the potential to emit 100 tpy or more of the criteria pollutant for which the area is designated nonattainment. If a facility already located in a nonattainment area wants to do a modification, it must go through the NA NSR process if the change would result in a net emissions increase above the thresholds noted above.

The following conditions must be met by a source before an NSR permit can be granted to a source located in a nonattainment area:

  1. The source must meet an emission limitation which specifies the lowest achievable emission rate (LAER) for that particular source.
  2. The source must certify that all other facilities it owns or operates in Minnesota are in compliance with all applicable requirements.
  3. The source must obtain emission reductions, or “offsets”, from existing sources in the same area of the proposed source or source modification. In addition, offsets are based on actual emissions and can only be intrapollutant (e.g., SO2 for SO2, not PM10 for SO2).

    For example, if Company X wants to locate a new major source in a SO2 nonattainment area, it must obtain SO2 emission offsets from another facility in the area. The facility that it obtains the emission offsets from can be owned by Company X or owned by another company. If Company X wants to do a SO2 major modification at Facility Z, it has three options to obtain SO2 offsets: the offsets can come right from Facility Z (internal netting), from another facility in the area owned by Company X, or from a facility in the area owned by any other company.

    Note that, at this time, Minnesota does not have a banking provision in its Offset rule, so emission reductions at a facility cannot be saved to provide offsets for a source seeking a permit in the future.
  4. Emission offsetting must provide a positive net air quality benefit in the nonattainment area. This means the emission offset must be greater than a one-to-one ratio. Dispersion modeling may also be needed to determine whether the new source or modification will attain the ambient air quality standards.

Revisions to the SIP may be required when there are amendments to the CAA, changes to EPA regulations (such as new NAAQS), or if the state initiates changes to its air program.

When the MPCA submits a SIP to EPA, whether it is a new plan or a revision to an existing plan, the SIP submittal includes:

  1. A formal letter of submittal to the EPA Regional Administrator from the Commissioner
  2. Copies of final, enforceable documents (such as administrative orders, permits with SIP conditions, or adopted rules) that contain emission limits and compliance requirements for culpable sources 
  3. Air dispersion modeling of the area showing projected or continued attainment of the NAAQS (if necessary) 
  4. Letters from the Attorney General’s Office or other documentation demonstrating that the state has legal authority to implement the SIP revision and that state procedural requirements were complied with in adopting the SIP 
  5. Copy of the public notice - every change to the SIP, no matter how small, is required to be public noticed for 30 days 
  6. If a public meeting is held, certification that it was held after a 30-day notice (a public meeting is not required but can always be requested during the comment period) 
  7. Any public comments received, along with MPCA’s response

The legal requirements for SIP submittals are found in the CAA, section 110, parts (a) and (d). All changes to the SIP require public notice and comment, and are then submitted to EPA for approval.

Sources that have site-specific SIP requirements may make changes to their operations that require changes to either their Administrative Order or Title I SIP conditions in their permits. Once approved by the EPA into the SIP, the requirements become federal rule. Therefore, compared to the general permit amendment process, revisions to these conditions tend to be more complex and lengthy. First, the MPCA prepare a SIP revision in addition to any needed permit changes. This must include a demonstration that the changes to the SIP-approved conditions will not jeopardize the area’s attainment status. The SIP revision must be public noticed at the state level, then submitted to and approved by EPA as a SIP revision, including going through the federal process of notice and comment in the Federal Register. This process can take over a year to complete, even for changes that would not otherwise be major amendments as defined under permitting rules. (All changes to SIP conditions must be major permit amendments.)

The MPCA’s policy of replacing Orders with federally enforceable air emission permits helps to alleviate some problems with the extended time frame. The permit can sometimes be written with more built-in operational flexibility than the original order, at least to the extent that changes to the facility that do not require a permit amendment are unlikely to require a SIP amendment. If the permit needs to be amended, the MPCA can usually give construction authorization through the permit so that the SIP amendment process and construction at the facility can occur in parallel. No additional public notice is necessary, provided that the public notice for the permit amendment includes a notice referring to pending changes in the SIP.

The MPCA and EPA have agreed to the following procedure for modifying site-specific SIP requirements (labeled Title I Condition: SIP for <pollutant>) in air quality permits:

  1. When the MPCA wants to modify a SIP requirement contained in the permit, MPCA will draft a permit amendment. Once the permit is drafted, EPA’s Title I SIP staff will be informed of pending SIP revisions, including the revised language and any supporting materials, and can comment if they find any problems with the Title I SIP language.
  2. The proposed permit amendment will include the new SIP conditions, with the caveat that these new SIP conditions will only become effective upon EPA approval of the SIP revision. The proposed permit amendment will continue to require compliance with the SIP requirements of the existing permit until the SIP is revised. (In other words, the company follows the “old” SIP requirements until EPA approves the “new” requirements into the SIP.) When the new requirements are approved, they become effective and the old requirements disappear. 
  3. The proposed permit amendment will be public noticed as a permit revision and as a Title I SIP revision. 
  4. In conjunction with the public participation process on the proposed permit and SIP amendments, the permit amendment will be sent to EPA for its 45-day permitting review. (Applies to Title V permits only). 
  5. If EPA has no SIP concerns or permitting objection to the proposed permit amendment, the MPCA will issue the permit amendment. Therefore, EPA’s permitting and SIP staff have not objected to the new SIP requirements, but the permitting staff also recognize and agree that they are not “applicable requirements” (under the permit) until the new requirements are approved into the SIP.
  6. The permit amendment is sent to EPA as a SIP revision. 

Once EPA SIP staff approve, and federal notice and comment procedures are complete, the Title I SIP conditions of the permit are incorporated into Minnesota’s SIP at the federal level.

Public notices for SIP revisions can be found on MPCA’s Public Notice Web page. If the SIP revision is being proposed in conjunction with a proposed permit, links to the proposed permit can also be found on that page.

There are currently no specific SIP revisions in progress. However, the MPCA is currently working on the following criteria pollutants:

Once a requirement is put into the SIP to control pollution, it does not expire. Even once the area attains the NAAQS, the requirements must stay in place in order to ensure that the NAAQS are maintained. Requirements may be revised through the previously described SIP revision process, but are subject to EPA approval. EPA reviews changes carefully to ensure there is no backsliding.

Minnesota had several areas designated as nonattainment for lead, PM10, and SO2 during the 1980s and 1990s. Although these areas were all redesignated to attainment by 2002, SIP requirements on various facilities remain in place. States must submit a SIP in order for EPA to redesignate a nonattainment area to attainment, when it is then known as a maintenance area. In order for the redesignation request to be approved, the state must already have an approved SIP for that area. The state must also show current modeled attainment, two years of monitoring without a violation, maintenance plans for maintaining the NAAQS for at least ten years, and, in some cases, contingency plans outlining procedures the state will implement in the event that the area violates the NAAQS. The MPCA is required to submit, for EPA approval, a second updated maintenance plan eight years after the redesignation to attainment to ensure maintenance of the NAAQS for an additional ten years.

The official boundaries of Minnesota’s current maintenance areas are as follows:

  • Carbon Monoxide:
    • The area within the official city limits of the city of St. Cloud contained within Benton, Sherburne, and Stearns Counties
    • City of Duluth 
    • Anoka, Hennepin, Ramsey, and portions of Carver, Dakota, Scott, Washington, and Wright Counties
  • Sulfur Dioxide: 
    • Seven county Twin Cities Metropolitan Area (Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, Washington) 
    • City of Rochester 
  • Particulate Matter (PM10): 
    • A portion of the city of Rochester, bounded on the south by U.S. Highway 14; on the west by U.S. Highway 52; on the north by 14th Street N.W. between U.S. Highway 52 and U.S. Route 63 (Broadway Avenue), U.S. Route 63 north to Northern Heights Drive, N.E. and Northern Heights Drive N.E. extended east to the 1990 city of Rochester limits; and on the east by the 1990 city of Rochester limits. 
    • A portion of the city of St. Paul bounded by the Mississippi River from Lafayette to Route 494, Route 494 east to Route 61, Route 61 north to I-94, I-94 west to Lafayette, and Lafayette south to the Mississippi River.

The official boundaries of Minnesota’s current nonattainment areas are as follows:

  • Lead
    • A portion of the city of Eagan bounded by Lone Oak Road (County Road 26) to the north, County Road 63 to the east, Westcott Road to the south, and Lexington Avenue (County Road 43) to the west.

SIPs that were submitted by states to the EPA and acted upon by the EPA are listed in 40 CFR pt. 52. Minnesota’s SIP is identified in 40 CFR § 52, subpart Y. Since the SIP has changed considerably since its original submittal, and the CFR is updated only annually, some of the items listed in 40 CFR § 52, subpart Y are obsolete and recent additions to the SIP may not be reflected. To view, go to the Code of Federal Regulations and retrieve 40 CFR pt. 52, subp. Y.
The document below lists the specific sources and facilities that are subject to limits established by the SIP, listed by geographic area and pollutant. It also includes a listing of the enforceable document that contains those requirements, the state effective date, and the federal approval and effective date. In addition, the document lists Minnesota’s SIP-included state rules. The MPCA’s SIP coordinator can supply current information on the status of the SIP.

The following links contain more detailed information about SIPs and what is included in Minnesota’s SIP.

More information