40 C.F.R. § 51.121 : Protection of Environment — ENVIRONMENTAL PROTECTION AGENCY — AIR PROGRAMS — REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS — CONTROL STRATEGY — Findings and requirements for submission of State implementation plan revisions relating to emissions of nitrogen oxides

(a)
(1) The Administrator finds that the State implementation plan (SIP) for each jurisdiction listed in paragraph (c) of this section is substantially inadequate to comply with the requirements of section 110(a)(2)(D)(i)(I) of the Clean Air Act (CAA), 42 U.S.C. 7410(a)(2)(D)(i)(I), because the SIP does not include adequate provisions to prohibit sources and other activities from emitting nitrogen oxides ("NO X") in amounts that will contribute significantly to nonattainment in one or more other States with respect to the 1-hour ozone national ambient air quality standards (NAAQS). Each of the jurisdictions listed in paragraph (c) of this section must submit to EPA a SIP revision that cures the inadequacy.
(2) [Reserved]
(3) As used in this section, these terms shall have the following meanings:

Nitrogen oxides or NOX means all oxides of nitrogen except nitrous oxide (N2O), reported on an equivalent molecular weight basis as nitrogen dioxide (NO2).

Ozone season means the period from May 1 to September 30 of a year.

Phase I SIP submission means a SIP revision submitted by a State on or before October 30, 2000 in compliance with paragraph (b)(1)(ii) of this section to limit projected NOX emissions during the ozone season from sources in the relevant portion or all of the State, as applicable, to no more than the State's Phase I NOX ozone season budget under paragraph (e) of this section.

Phase II SIP submission means a SIP revision submitted by a State in compliance with paragraph (b)(1)(ii) of this section to limit projected NOX emissions during the ozone season from sources in the relevant portion or all of the State, as applicable, to no more than the State's final NOX ozone season budget under paragraph (e) of this section.

(b)
(1) For each jurisdiction listed in paragraph (c) of this section, each SIP revision required under paragraph (a) of this section will contain adequate provisions, for purposes of complying with section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if the SIP revision:
(i) Contains control measures adequate to prohibit emissions of NO X that would otherwise be projected, in accordance with paragraph (g) of this section, to cause the jurisdiction's overall NO X emissions during the ozone season to be in excess of the applicable NO X ozone season budget for that jurisdiction described in paragraph (e) of this section;
(ii) Requires full implementation of all such control measures by no later than May 31, 2004 for the sources covered by a Phase I SIP submission and May 1, 2007 for the sources covered by a Phase II SIP submission; and
(iii) Meets the other requirements of this section. The SIP revision's compliance with the requirement of paragraph (b)(1)(i) of this section shall be considered compliance with the jurisdiction's NO X ozone season budget for purposes of this section.
(2) {Reserved]
(c) The following jurisdictions (hereinafter referred to as "States") are subject to the requirement of this section:
(1) Connecticut, Delaware, Illinois, Indiana, Kentucky, Maryland, Massachusetts, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, West Virginia, and the District of Columbia.
(2) The portions of Alabama, Michigan, and Missouri within the fine grid of the OTAG modeling domain. The fine grid is the area encompassed by a box with the following geographic coordinates: Southwest Corner, 92 degrees West longitude and 32 degrees North latitude; and Northeast Corner, 69.5 degrees West longitude and 44 degrees North latitude.
(d)
(1) [Reserved]
(2) Each SIP submission under this section must comply with § 51.103 (regarding submission of plans).
(e)
(1) Except as provided in paragraph (e)(2)(ii) of this section, the NO X ozone season budget for a State listed in paragraph (c) of this section is defined as the total amount of NO X emissions from all sources in that State, as indicated in paragraph (e)(2)(i) of this section with respect to that State, which the State must demonstrate that it will not exceed in the 2007 ozone season pursuant to paragraph (g)(1) of this section.
(2)
(i) The State-by-State amounts of the Phase I and final NO X ozone season budgets, expressed in tons, are listed in Table 1 to this paragraph (e)(2)(i):

TABLE 1 TO PARAGRAPH (E)(2)(I)-STATE NOX OZONE SEASON BUDGETS

State Phase I NOX ozone season budget
(2004-2006)		 Final NOX ozone season budget
(2007 and thereafter)
Alabama 124,795 119,827
Connecticut 42,891 42,850
Delaware 23,522 22,862
District of Columbia 6,658 6,657
Illinois 278,146 271,091
Indiana 234,625 230,381
Kentucky 165,075 162,519
Maryland 82,727 81,947
Massachusetts 85,871 84,848
Michigan 191,941 190,908
Missouri 61,406
New Jersey 95,882 96,876
New York 241,981 240,322
North Carolina 171,332 165,306
Ohio 252,282 249,541
Pennsylvania 268,158 257,928
Rhode Island 9,570 9,378
South Carolina 127,756 123,496
Tennessee 201,163 198,286
Virginia 186,689 180,521
West Virginia 85,045 83,921

(ii)
(A) For purposes of paragraph (e)(2)(i) of this section, in the case of each State listed in paragraphs (e)(2)(ii)(B) through (E) of this section, the NO X ozone season budget is defined as the total amount of NO X emissions from all sources in the specified counties in that State, as indicated in paragraph (e)(2)(i) of this section with respect to the State, which the State must demonstrate that it will not exceed in the 2007 ozone season pursuant to paragraph (g)(1) of this section.
(B) In the case of Alabama, the counties are: Autauga, Bibb, Blount, Calhoun, Chambers, Cherokee, Chilton, Clay, Cleburne, Colbert, Coosa, Cullman, Dallas, DeKalb, Elmore, Etowah, Fayette, Franklin, Greene, Hale, Jackson, Jefferson, Lamar, Lauderdale, Lawrence, Lee, Limestone, Macon, Madison, Marion, Marshall, Morgan, Perry, Pickens, Randolph, Russell, St. Clair, Shelby, Sumter, Talladega, Tallapoosa, Tuscaloosa, Walker, and Winston.
(C) [Reserved]
(D) In the case of Michigan, the counties are: Allegan, Barry, Bay, Berrien, Branch, Calhoun, Cass, Clinton, Eaton, Genesee, Gratiot, Hillsdale, Ingham, Ionia, Isabella, Jackson, Kalamazoo, Kent, Lapeer, Lenawee, Livingston, Macomb, Mecosta, Midland, Monroe, Montcalm, Muskegon, Newaygo, Oakland, Oceana, Ottawa, Saginaw, St. Clair, St. Joseph, Sanilac, Shiawassee, Tuscola, Van Buren, Washtenaw, and Wayne.
(E) In the case of Missouri, the counties are: Bollinger, Butler, Cape Girardeau, Carter, Clark, Crawford, Dent, Dunklin, Franklin, Gasconade, Iron, Jefferson, Lewis, Lincoln, Madison, Marion, Mississippi, Montgomery, New Madrid, Oregon, Pemiscot, Perry, Pike, Ralls, Reynolds, Ripley, St. Charles, St. Francois, St. Louis, St. Louis City, Ste. Genevieve, Scott, Shannon, Stoddard, Warren, Washington, and Wayne.
(f) Each SIP revision must set forth control measures to meet the NO X ozone season budget in accordance with paragraph (b)(1)(i) of this section, which include the following:
(1) A description of enforcement methods including, but not limited to:
(i) Procedures for monitoring compliance with each of the selected control measures;
(ii) Procedures for handling violations; and
(iii) A designation of agency responsibility for enforcement of implementation.
(2) Should a State elect to impose control measures on fossil fuel-fired NO X sources serving electric generators with a nameplate capacity greater than 25 MWe or boilers, combustion turbines or combined cycle units with a maximum design heat input greater than 250 mmBtu/hr as a means of meeting its NO X ozone season budget, then those measures must:
(i)
(A) Impose a NO X mass emissions cap on each source;
(B) Impose a NO X emissions rate limit on each source and assume maximum operating capacity for every such source for purposes of estimating NO X mass emissions; or
(C) Impose any other regulatory requirement which the State has demonstrated to EPA provides equivalent or greater assurance than options in paragraph (f)(2)(i)(A) or (B) of this section that the State will comply with its NO X ozone season budget in the 2007 ozone season; and
(ii) Impose enforceable mechanisms, in accordance with paragraphs (b)(1)(i) and (ii) of this section, to assure that collectively all such sources, including new or modified units, will not exceed in the 2007 ozone season the total NO X emissions projected for such sources by the State pursuant to paragraph (g) of this section.
(3) For purposes of paragraph (f)(2) of this section, the term "fossil fuel-fired" means, with regard to a NO X source:
(i) The combustion of fossil fuel, alone or in combination with any other fuel, where fossil fuel actually combusted comprises more than 50 percent of the annual heat input on a Btu basis during any year starting in 1995 or, if a NO X source had no heat input starting in 1995, during the last year of operation of the NO X source prior to 1995; or
(ii) The combustion of fossil fuel, alone or in combination with any other fuel, where fossil fuel is projected to comprise more than 50 percent of the annual heat input on a Btu basis during any year; provided that the NO X source shall be "fossil fuel-fired" as of the date, during such year, on which the NO X source begins combusting fossil fuel.
(g)
(1) Each SIP revision must demonstrate that the control measures contained in it are adequate to provide for the timely compliance with the State's NO X ozone season budget during the 2007 ozone season.
(2) The demonstration must include the following:
(i) Each revision must contain a detailed baseline inventory of NO X mass emissions during the ozone season from the following sources in the year 2007, absent the control measures specified in the SIP submission: electric generating units (EGU), non-electric generating units (non-EGU), area, nonroad and highway sources. The State must use the same baseline emissions inventory that EPA used in calculating the State's NO X ozone season budget, except that EPA may direct the State to use different baseline inventory information if the State fails to certify that it has implemented all of the control measures assumed in developing the baseline inventory.
(ii) [Reserved]
(iii) Each revision must contain a summary of NO X mass emissions during the ozone season in 2007 projected to result from implementation of each of the control measures specified in the SIP submission and from all NO X sources together following implementation of all such control measures, compared to the baseline 2007 NO X emissions inventory for the State described in paragraph (g)(2)(i) of this section. The State must provide EPA with a summary of the computations, assumptions, and judgments used to determine the degree of reduction in projected 2007 NO X emissions that will be achieved from the implementation of the new control measures compared to the baseline emissions inventory.
(iv) Each revision must identify the sources of the data used in the projection of emissions.
(h) Each revision must comply with § 51.116 (regarding data availability).
(i) Each revision must provide for monitoring the status of compliance with any control measures adopted to meet the NO X ozone season budget. Specifically, the revision must meet the following requirements:
(1) The revision must provide for legally enforceable procedures for requiring owners or operators of stationary sources to maintain records of and periodically report to the State:
(i) Information on the amount of NO X emissions from the stationary sources; and
(ii) Other information as may be necessary to enable the State to determine whether the sources are in compliance with applicable portions of the control measures;
(2) The revision must comply with § 51.212 (regarding testing, inspection, enforcement, and complaints);
(3) If the revision contains any transportation control measures, then the revision must comply with § 51.213 (regarding transportation control measures);
(4) If the revision contains measures to control fossil fuel-fired NO X sources serving electric generators with a nameplate capacity greater than 25 MWe or boilers, combustion turbines or combined cycle units with a maximum design heat input greater than 250 mmBtu/hr, then the revision may require some or all such sources to comply with the full set of monitoring, recordkeeping, and reporting provisions of 40 CFR part 75, subpart H. A State requiring such compliance authorizes the Administrator to assist the State in implementing the revision by carrying out the functions of the Administrator under such part.
(5) For purposes of paragraph (i)(4) of this section, the term "fossil fuel-fired" has the meaning set forth in paragraph (f)(3) of this section.
(j) Each revision must show that the State has legal authority to carry out the revision, including authority to:
(1) Adopt emissions standards and limitations and any other measures necessary for attainment and maintenance of the State's NO X ozone season budget specified in paragraph (e) of this section;
(2) Enforce applicable laws, regulations, and standards, and seek injunctive relief;
(3) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources;
(4) Require owners or operators of stationary sources to install, maintain, and use emissions monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; also authority for the State to make such data available to the public as reported and as correlated with any applicable emissions standards or limitations.
(k)
(1) The provisions of law or regulation which the State determines provide the authorities required under this section must be specifically identified, and copies of such laws or regulations must be submitted with the SIP revision.
(2) Legal authority adequate to fulfill the requirements of paragraphs (j)(3) and (4) of this section may be delegated to the State under section 114 of the CAA, 42 U.S.C. 7414.
(l)
(1) A revision may assign legal authority to local agencies in accordance with § 51.232.
(2) Each revision must comply with § 51.240 (regarding general plan requirements).
(m) Each revision must comply with § 51.280 (regarding resources).
(n) For purposes of the SIP revisions required by this section, EPA may make a finding as applicable under section 179(a)(1)-(4) of the CAA, 42 U.S.C. 7509(a)(1)-(4), starting the sanctions process set forth in section 179(a) of the CAA. Any such finding will be deemed a finding under 40 CFR 52.31(c) and sanctions will be imposed in accordance with the order of sanctions and the terms for such sanctions established in 40 CFR 52.31.
(o) Each revision must provide for State compliance with the reporting requirements set forth in § 51.122.
(p) -(q) [Reserved]
(r)
(1) Notwithstanding any provisions of subparts A through I of 40 CFR part 96 and any State's SIP to the contrary, with regard to any ozone season that occurs after September 30, 2008, the Administrator will not carry out any of the functions set forth for the Administrator in subparts A through I of 40 CFR part 96 or in any emissions trading program provisions in a State's SIP approved under this section.
(2) Except as provided in 40 CFR 52.38(b)(13)(ii), a State whose SIP is approved as meeting the requirements of this section and that includes or included an emissions trading program approved under this section must revise the SIP to adopt control measures that satisfy the same portion of the State's NO X emissions reduction requirements under this section as the State projected such emissions trading program would satisfy.

40 C.F.R. §51.121

63 FR 57491, 10/27/1998, as amended at 63 FR 71225, 12/24/1998; 64 FR 26305, 5/14/1999; 65 FR 11230, 3/2/2000; 65 FR 56251, 9/18/2000; 69 FR 21642, 4/21/2004; 70 FR 25317, 5/12/2005; 70 FR 51597, 8/31/2005; 73 FR 21538, 4/22/2008; 76 FR 48353, 8/8/2011; 79 FR 71671, 12/3/2014; 84 FR 8442, 3/8/2019; 86 FR 23164, 6/29/2021