PLAAPCD APPENDIX B
LAST REVISED 11/11/11

                       FEDERAL GENERAL CONFORMITY REGULATION

          The Code of Federal Regulations, title 40, chapter I, subchapter
          C, parts 6 and 51 are amended and part 93 is added as follows:
          PART 6--[AMENDED]
          1.   The authority citation for part 51 continues to read as
               follows:
               Authority:  42 U.S.C. 7401-7671q.
          2.   Section 6.303 is amended by reserving paragraphs (c) through
               (g) and revising paragraphs (a) and (b) to read as follows:
               (a)  The Clean Air Act, as amended in 1990, 42 U.S.C.
                    7476(c), requires Federal actions to conform to any
                    State implementation plan approved or promulgated under
                    section 110 of the Act.  For EPA actions, the
                    applicable conformity requirements specified in 40 CFR
                    part 51, subpart W, 40 CFR part 93, subpart B, and the
                    applicable State implementation plan must be met.
               (b)  In addition, with regard to wastewater treatment works
                    subject to review under Subpart E of this part, the
                    responsible official shall consider the air pollution
                    control requirements specified in section 316(b) of the
                    Clean Air Act, 42 U.S.C. 7616, and Agency
                    implementation procedures.

          PART 51--[AMENDED]
          1.   The authority citation for part 51 continues to read as
               follows:
               Authority:  42 U.S.C. 7401-7671q.
          2.   Part 51 is amended by adding a new subpart W to read as
               follows:

          W -- DETERMINING CONFORMITY OF GENERAL FEDERAL ACTIONS TO STATE
          OR FEDERAL IMPLEMENTATION PLANS

          Sec.
          51.850    Prohibition.
          51.851    State implementation plan (SIP) revision.
          51.852    Definitions.
          51.853    Applicability.
          51.854    Conformity analysis.
          51.855    Reporting requirements.
          51.856    Public participation.
          51.857    Frequency of conformity determinations.
          51.858    Criteria for determining conformity of general Federal
                    actions.
          51.859    Procedures for conformity determinations of general
                    Federal actions.
          51.860    Mitigation of air quality impacts.

          W -- DETERMINING CONFORMITY OF GENERAL FEDERAL ACTIONS TO STATE
          OR FEDERAL IMPLEMENTATION PLANS

           51.850  Prohibition.

          (a)  No department, agency or instrumentality of the Federal
               Government shall engage in, support in any way or provide
               financial assistance for, license or permit, or approve any
               activity which does not conform to an applicable
               implementation plan.
          (b)  A Federal agency must make a determination that a Federal
               action conforms to the applicable implementation plan in
               accordance with the requirements of this rule before the
               action is taken.
          (c)  The preceding sentence does not include Federal actions
               where either:
               (1)  A National Environmental Policy Act (NEPA) analysis was
                    completed as evidenced by  a final environmental
                    assessment (EA), environmental impact statement (EIS),
                    or finding of no significant impact (FONSI) that was
                    prepared prior to the effective date of this rule, or
               (2)  (i)  Prior to the effective date of this rule, an EA
                         was commenced or a contract was awarded to develop
                         the specific environmental analysis,
                    (ii) Sufficient environmental analysis is completed by
                         March 15, 1994 so that the Federal agency may
                         determine that the Federal action is in conformity
                         with the specific requirements and the purposes of
                         the applicable SIP pursuant to the agency's
                         affirmative obligation under section 176(c) of the
                         Clean Air Act (Act), and
                    (iii)A written determination of conformity under
                         section 176(c) of the Act has been made by the
                         Federal agency responsible for the Federal action
                         by March 15, 1994.
          (d)  Notwithstanding any provision of this subpart, a
               determination that an action is in conformance with the
               applicable implementation plan does not exempt the action
               from any other requirements of the applicable implementation
               plan, the NEPA, or the Act.

          51.851   State implementation plan (SIP) revision.

          (a)  Each State must submit to the Environmental Protection
               Agency (EPA) a revision to its applicable implementation
               plan which contains criteria and procedures for assessing
               the conformity of Federal actions to the applicable
               implementation plan, consistent with this subpart.  The
               State must submit the conformity provisions within 12 months
               after November 31, 1993, or within 12 months of an area's
               designation to nonattainment, whichever date is later.
          (b)  The Federal conformity rules under this subpart and 40 CFR
               part 93, in addition to any existing applicable State
               requirements, establish the conformity criteria and
               procedures necessary to meet the Act requirements until such
               time as the required conformity SIP revision is approved by
               EPA.  A State's conformity provisions must contain criteria
               and procedures that are no less stringent than the
               requirements described in this subpart.  A State may
               establish more stringent conformity criteria and procedures
               only if they apply equally to non-Federal as well as Federal
               entities.  Following EPA approval of the State conformity
               provisions (or a portion thereof) in a revision to the
               applicable SIP, the approved (or approved portion of the)
               State criteria and procedures would govern conformity
               determinations and the Federal conformity regulations
               contained in 40 CFR part 93 would apply only for the
               portion, if any, of the State's conformity provisions that
               is not approved by EPA.  In addition, any previously
               applicable SIP requirements relating to conformity remain
               enforceable until the State revises its SIP to specifically
               remove them from the SIP and that revision is approved by
               EPA.

          51.852  Definitions.

          Terms used but not defined in this part shall have the meaning given them
          by the Act and EPA's regulations, in that order of priority.
               Affected Federal land manager means the Federal agency or
               the Federal official charged with direct responsibility for
               management of an area designated as Class I under 42 U.S.C.
               7472 of  the Act that is located within 100 km of the
               proposed Federal action.
               Applicable implementation plan or applicable SIP means the
               portion (or portions) of the SIP or most recent revision
               thereof, which has been approved under section 110 of the
               Act, or promulgated under section 110(c) of the Act (Federal
               implementation plan), or promulgated or approved pursuant to
               regulations promulgated under section 301(d) of the Act and
               which implements the relevant requirements of the Act.
               Areawide air quality modeling analysis means an assessment
               on a scale that includes the entire nonattainment or
               maintenance area which uses an air quality dispersion model
               to determine the effects of emissions on air quality.
               Cause or contribute to a new violation means a Federal
               action that:
               (1)  Causes a new violation of a national ambient air
                    quality standard (NAAQS) at a location in a
                    nonattainment or maintenance area which would otherwise
                    not be in violation of the standard during the future
                    period in question if the Federal action were not
                    taken, or
               (2)  Contributes, in conjunction with other reasonably
                    foreseeable actions, to a new violation of a NAAQS at a
                    location in a nonattainment or maintenance area in a
                    manner that would increase the frequency or severity of
                    the new violation.
               Caused by, as used in the terms "direct emissions" and
               "indirect emissions," means emissions that would not
               otherwise occur in the absence of the Federal action.
               Criteria pollutant or standard means any pollutant for which
               there is established a NAAQS at 40 CFR part 50.
               Direct emissions means those emissions of a criteria
               pollutant or its precursors that are caused or initiated by
               the Federal action and occur at the same time and place as
               the action.
               Emergency means a situation where extremely quick action on
               the part of the Federal agencies involved is needed and
               where the timing of such Federal activities makes it
               impractical to meet the requirements of this rule, such as
               natural disasters like hurricanes or earthquakes, civil
               disturbances such as terrorist acts, and military
               mobilizations.
               Emissions budgets are those portions of the applicable SIP's
               projected emissions inventories that describe the levels of
               emissions (mobile, stationary, area, etc.) that provide for
               meeting reasonable further progress milestones, attainment,
               and/or maintenance for any criteria pollutant or its
               precursors.
               Emission offsets, for purposes of section 51.858, are
               emissions reductions which are quantifiable, consistent with
               the applicable SIP attainment and reasonable further
               progress demonstrations, surplus to reductions required by,
               and credited to, other applicable SIP provisions,
               enforceable at both the State and Federal levels, and
               permanent within the timeframe specified by the program.
               Emissions that a Federal agency has a continuing program
               responsibility for means emissions that are specifically
               caused by an agency carrying out its authorities, and does
               not include emissions that occur due to subsequent
               activities, unless such activities are required by the
               Federal agency.  Where an agency, in performing its normal
               program responsibilities, takes actions itself or imposes
               conditions that result in air pollutant emissions by a non-
               Federal entity taking subsequent actions, such emissions are
               covered by the meaning of a continuing program
               responsibility.
               EPA means the United States Environmental Protection Agency.
               Federal action means any activity engaged in by a
               department,  agency, or instrumentality of the Federal
               government, or any activity that a department, agency or
               instrumentality of the Federal government supports in any
               way, provides financial assistance for, licenses, permits,
               or approves, other than activities related to transportation
               plans, programs, and projects developed, funded, or approved
               under title 23 U.S.C. or the Federal Transit Act (49 U.S.C.
               1601 et seq.).  Where the Federal action is a permit,
               license, or other approval for some aspect of a non-Federal
               undertaking, the relevant activity is the part, portion, or
               phase or the non-Federal undertaking that requires the
               Federal permit, license, or approval.
               Federal agency means, for purposes of this rule, a Federal
               department, agency, or instrumentality of the Federal
               government.
               Increase the frequency or severity of any existing violation
               of any standard in any area means to cause a nonattainment
               area to exceed a standard more often or to cause a violation
               at a greater concentration than previously existed and/or
               would otherwise exist during the future period in question,
               if the project were not implemented.
               Indirect emissions means those emissions of a criteria
               pollutant or its precursors that:
               (1)  Are caused by the Federal action, but may occur later
               in time and/or may be farther removed in distance from the
               action itself but are still reasonably foreseeable, and
               (2)  The Federal agency can practicably control and will
               maintain control over due to a continuing program
               responsibility of the Federal agency.
               Local air quality modeling analysis means an assessment of
               localized impacts on a scale smaller than the entire
               nonattainment or maintenance area, including, for example,
               congested roadway intersections and highways or transit
               terminals, which uses an air quality dispersion model to
               determine the effects of emissions on air quality.
               Maintenance area means an area with a maintenance plan
               approved under section 175A of the Act.
               Maintenance plan means a revision to the applicable SIP,
               meeting the requirements of section 175A of the Act.
               Metropolitan Planning Organization (MPO) is that
               organization designated as being responsible, together with
               the State, for conducting the continuing, cooperative, and
               comprehensive planning process under 23 U.S.C. 134 and 49
               U.S.C. 1607.
               Milestone has the meaning given in sections 182(g)(1) and
               189(c)(1) of the Act.
               National ambient air quality standards (NAAQS) are those
               standards established pursuant to section 109 of the Act and
               include standards for carbon monoxide (CO), lead (Pb),
               nitrogen dioxide (NO2), ozone, particulate matter (PM-10),
               and sulfur dioxide (SO2).
               NEPA is the National Environmental Policy Act of 1969, as
               amended (42 U.S.C. 4321 et seq.).
               Nonattainment Area (NAA) means an area designated as
               nonattainment under section 107 of the Act and described in
               40 CFR part 81.
               Precursors of a criteria pollutant are:
               (1)  For ozone, nitrogen oxides (NOx), unless an area is
                    exempted from NOx requirements under section 182(f) of
                    the Act, and volatile organic compounds (VOC) and
               (2)  For PM-10, those pollutants described in the PM-10
                    nonattainment area applicable SIP as significant
                    contributors to the PM-10 levels.
               Reasonably foreseeable emissions are projected future
               indirect emissions that are identified at the time the
               conformity determination is made; the location of such
               emissions is known and the emissions are quantifiable, as
               described and documented by the Federal agency based on its
               own information and after reviewing any information
               presented to the Federal agency.
               Regionally significant action means a Federal action for
               which the direct and indirect emissions of any pollutant
               represent 10 percent or more of a nonattainment or
               maintenance area's emissions inventory for that pollutant.
               Regional water and/or wastewater projects include
               construction, operation, and maintenance of water or
               wastewater conveyances, water or wastewater treatment
               facilities, and water storage reservoirs which affect a
               large portion of a nonattainment or maintenance area.
               Total of direct and indirect emissions means the sum of
               direct and indirect emissions increases and decreases caused
               by the Federal action; i.e., the "net" emissions considering
               all direct and indirect emissions.  The portion of emissions
               which are exempt or presumed to conform under section
               51.853, paragraph (c), (d), (e), or (f) are not included in
               the "total of direct and indirect emissions."  The "total of
               direct and indirect emissions" includes emissions of
               criteria pollutants and emissions of precursors of criteria
               pollutants.

          51.853   Applicability.

          (a)  Conformity determinations for Federal actions related to
               transportation plans, programs, and projects developed,
               funded, or approved under title 23 U.S.C. or the Federal
               Transit Act (49 U.S.C. 1601 et seq.) must meet the
               procedures and criteria of 40 CFR part 51, subpart T, in
               lieu of the procedures set forth in this subpart.
          (b)  For Federal actions not covered by paragraph (a) of this
               section, a conformity determination is required for each
               pollutant where the total of direct and indirect emissions
               in a nonattainment or maintenance area caused by a Federal
               action would equal or exceed any of the rates in paragraphs
               (b)(1) or (2) of this section.
               (1)  For purposes of paragraph (b) of this section, the
                    following rates apply in nonattainment areas (NAAs):
                                                         Tons/Year
                         Ozone (VOC's or NOx)
                         Serious NAA's                       50
                         Severe NAA's                        25
                         Extreme NAA's                       10
                         Other ozone NAA's outside an
                            ozone transport region          100
                         Marginal and moderate NAA's
                            inside an ozone transport region
                              VOC                            50
                              NOx                           100
                    Carbon monoxide
                              All NAA's                     100
                    SO2 or NO2
                              All NAA's                     100
                    PM-10
                              Moderate NAA's                100
                              Serious NAA's                  70
                    Pb
                              All NAA's                      25

               (2)  For purposes of paragraph (b) of this section, the
                    following rates apply in maintenance areas:
                                                             Tons/Year
                    Ozone (NOx), SO2 or NO2
                                   All Maintenance Area         100
                    Ozone (VOC's)
                                   Maintenance areas inside
                          an ozone transport region              50
                         Maintenance areas outside
                          an ozone transport region             100
                    Carbon monoxide
                                   All maintenance ar           100
                    PM-10
                                   All maintenance              100
                    Pb
                                   All maintenanc                25

          (c)  The requirements of this subpart shall not apply to:
               (1)  Actions where the total of direct and indirect
                    emissions are below the emissions levels specified in
                    paragraph (b) of this section.
               (2)  The following actions which would result in no
                    emissions increase or an increase in emissions that is
                    clearly de minimis:
                    (i)  Judicial and legislative proceedings.
                    (ii) Continuing and recurring activities such as permit
                         renewals where activities conducted will be
                         similar in scope and operation to activities
                         currently being conducted.
                    (iii)     Rulemaking and policy development and
                              issuance.
                    (iv) Routine maintenance and repair activities,
                         including repair and maintenance of administrative
                         sites, roads, trails, and facilities.
                    (v)  Civil and criminal enforcement activities, such as
                         investigations, audits, inspections, examinations,
                         prosecutions, and the training of law enforcement
                         personnel.
                    (vi) Administrative actions such as personnel actions,
                         organizational changes, debt management or
                         collection, cash management, internal agency
                         audits, program budget proposals, and matters
                         relating to the administration and collection of
                         taxes, duties and fees.
                    (vii)     The routine, recurring transportation of
                              materiel and personnel.
                    (viii)    Routine movement of mobile assets, such as
                              ships and aircraft, in home port
                              reassignments and stations (when no new
                              support facilities or personnel are required)
                              to perform as operational groups and/or for
                              repair or overhaul.
                    (ix) Maintenance dredging and debris disposal where no
                         new depths are required, applicable permits are
                         secured, and disposal will be at an approved
                         disposal site.
                    (x)  Actions, such as the following, with respect to
                         existing structures, properties, facilities and
                         lands where future activities conducted will be
                         similar in scope and operation to activities
                         currently being conducted at the existing
                         structures, properties, facilities, and lands; for
                         example, relocation of personnel, disposition  of
                         federally-owned existing structures, properties,
                         facilities, and lands, rent subsidies, operation
                         and maintenance cost subsidies, the exercise of
                         receivership or conservatorship authority,
                         assistance in purchasing structures, and the
                         production of coins and currency.
                    (xi) The granting of leases, licenses such as for
                         exports and trade, permits, and easements where
                         activities conducted will be similar in scope and
                         operation to activities currently being conducted.
                    (xii)     Planning, studies, and provision of technical
                              assistance.
                    (xiii)    Routine operation of facilities, mobile
                              assets and equipment.
                    (xiv)     Transfers of ownership, interests, and titles
                              in land, facilities, and real and personal
                              properties, regardless of the form or method
                              of the transfer.
                    (xv) The designation of empowerment zones, enterprise
                         communities, or viticultural areas.
                    (xvi)     Actions by any of the Federal banking
                              agencies or the Federal Reserve Banks,
                              including actions regarding charters,
                              applications, notices, licenses, the
                              supervision or examination of depository
                              institutions or depository institution
                              holding companies, access to the discount
                              window, or the provision of financial
                              services to banking organizations or to any
                              department, agency or instrumentality of the
                              United States.
                    (xvii)    Actions by the Board of Governors of the
                              Federal Reserve System or any Federal Reserve
                              Bank to effect monetary or exchange rate
                              policy.
                    (xviii)   Actions that implement a foreign affairs
                              function of the United States.
                    (xix)     Actions (or portions thereof) associated with
                              transfers of land, facilities, title, and
                              real properties through an enforceable
                              contract or lease agreement where the
                              delivery of the deed is required to occur
                              promptly after a specific, reasonable
                              condition is met, such as promptly after the
                              land is certified as meeting the requirements
                              of the Comprehensive Environmental Response,
                              Compensation, and Liability Act (CERCLA), and
                              where the Federal agency does not retain
                              continuing authority to control emissions
                              associated with the lands, facilities, title,
                              or real properties.
                    (xx) Transfers of real property, including land,
                         facilities, and related personal property from a
                         Federal entity to another Federal entity and
                         assignments of real property, including land,
                         facilities, and related personal property from a
                         Federal entity to another Federal entity for
                         subsequent deeding to eligible applicants.
                    (xxi)     Actions by the Department of the Treasury to
                              effect fiscal policy and to exercise the
                              borrowing authority of the United States.
               (3)  Actions where the emissions are not reasonably
                    foreseeable, such as the following:
                    (i)  Initial Outer Continental Shelf lease sales which
                         are made on a broad scale and are followed by
                         exploration and development plans on a project
                         level.
                    (ii) Electric power marketing activities that involve
                         the acquisition, sale and transmission of electric
                         energy.
               (4)  Actions which implement a decision to conduct or carry
                    out a conforming program such as prescribed burning
                    actions which are consistent with a conforming land
                    management plan.
          (d)  Notwithstanding the other requirements of this subpart, a
               conformity determination is not required for the following
               Federal actions (or portion thereof):
               (1)  The portion of an action that includes major new or
                    modified stationary sources that require a permit under
                    the new source review (NSR) program (section 173 of the
                    Act) or the prevention of significant deterioration
                    (PSD) program (title I, part C of the Act).
               (2)  Actions in response to emergencies or natural disasters
                    such as hurricanes, earthquakes, etc., which are
                    commenced on the order of hours or days after the
                    emergency or disaster and, if applicable, which meet
                    the requirements of paragraph (e) of this section;
               (3)  Research, investigations, studies, demonstrations, or
                    training [other than those exempted under section
                    51.853(c)(2)], where no environmental detriment is
                    incurred and/or, the particular action furthers air
                    quality research, as determined by the State agency
                    primarily responsible for the applicable SIP;
               (4)  Alteration and additions of existing structures as
                    specifically required by new or existing applicable
                    environmental legislation or environmental regulations
                    (e.g., hush houses for aircraft engines and scrubbers
                    for air emissions).
               (5)  Direct emissions from remedial and removal actions
                    carried out under the Comprehensive Environmental
                    Response, Compensation and Liability Act (CERCLA) and
                    associated regulations to the extent such emissions
                    either comply with the substantive requirements of the
                    PSD/NSR permitting program or are exempted from other
                    environmental regulation under the provisions of CERCLA
                    and applicable regulations issued under CERCLA.
          (e)  Federal actions which are part of a continuing response to
               an emergency or disaster under section 51.853(d)(2) and
               which are to be taken more than 6 months after the
               commencement of the response to the emergency or disaster
               under section 51.853(d)(2) are exempt from the requirements
               of this subpart only if:
               (1)  The Federal agency taking the actions makes a written
                    determination that, for a specified period not to
                    exceed an additional 6 months, it is impractical to
                    prepare the conformity analyses which would otherwise
                    be required and the actions cannot be delayed due to
                    overriding concerns for public health and welfare,
                    national security interests and foreign policy
                    commitments; or
               (2)  For actions which are to be taken after those actions
                    covered by paragraph (e)(1) of this section, the
                    Federal agency makes a new determination as provided in
                    paragraph (e)(1) of this section.
          (f)  Notwithstanding other requirements of this subpart, actions
               specified by individual Federal agencies that have met the
               criteria set forth in either paragraph (g)(1) or (g)(2) and
               the  procedures set forth in paragraph (h) of this section
               are presumed to conform, except as provided in paragraph (j)
               of this section.
          (g)  The Federal agency must meet the criteria for establishing
               activities that are presumed to conform by fulfilling the
               requirements set forth in either paragraph (g)(1) or (g)(2)
               of this section:
               (1)  The Federal agency must clearly demonstrate using
                    methods consistent with this rule that the total of
                    direct and indirect emissions from the type of
                    activities which would be presumed to conform would
                    not:
                    (i)  Cause or contribute to any new violation of any
                         standard in any area;
                    (ii) Interfere with provisions in the applicable SIP
                         for maintenance of any standard;
                    (iii)     Increase the frequency or severity of any
                              existing violation of any standard in any
                              area; or
                    (iv) Delay timely attainment of any standard or any
                         required interim emission reductions or other
                         milestones in any area including, where
                         applicable, emission levels specified in the
                         applicable SIP for purposes of:
                         (A)  A demonstration of reasonable further
                              progress;
                         (B)  A demonstration of attainment; or
                         (C)  A maintenance plan; or
               (2)  The Federal agency must provide documentation that the
                    total of direct and indirect emissions from such future
                    actions would be below the emission rates for a
                    conformity determination that are established in
                    paragraph (b) of this section, based, for example, on
                    similar actions taken over recent years.
          (h)  In addition to meeting the criteria for establishing
               exemptions set forth in paragraphs (g)(1) or (g)(2) of this
               section, the following procedures must also be complied with
               to presume that activities will conform:
               (1)  The Federal agency must identify through publication in
                    the Federal Register its list of proposed activities
                    that are presumed to conform and the basis for the
                    presumptions;
               (2)  The Federal agency must notify the appropriate EPA
                    Regional Office(s), State and local air quality
                    agencies and, where applicable, the agency designated
                    under section 174 of the Act and the MPO and provide at
                    least 30 days for the public to comment on the list of
                    proposed activities presumed to conform;
               (3)  The Federal agency must document its response to all
                    the comments received and make the comments, response,
                    and final list of activities available to the public
                    upon request; and
               (4)  The Federal agency must publish the final list of such
                    activities in the Federal Register.
          (i)  Notwithstanding the other requirements of this subpart, when
               the total of direct and indirect emissions of any pollutant
               from a Federal action does not equal or exceed the rates
               specified in paragraph (b) of this section, but represents
               10 percent or more of a nonattainment or maintenance area's
               total emissions of that  pollutant, the action is defined as
               a regionally significant action and the requirements of
               section 51.850 and sections 51.855-860 shall apply for the
               Federal action.
          (j)  Where an action otherwise presumed to conform under
               paragraph (f) of this section is a regionally significant
               action or does not in fact meet one of the criteria in
               paragraph (g)(1) of this section, that action shall not be
               presumed to conform and the requirements of section 51.850
               and sections 51.855-860 shall apply for the Federal action.
          (k)  The provisions of this subpart shall apply in all
               nonattainment and maintenance areas.

          51.854   Conformity analysis.

          Any Federal department, agency, or instrumentality of the Federal
          government taking an action subject to this subpart must make its
          own conformity determination consistent with the requirements of
          this subpart.  In making its conformity determination, a Federal
          agency must consider comments from any interested parties.  Where
          multiple Federal agencies have jurisdiction for various aspects
          of a project, a Federal agency may choose to adopt the analysis
          of another Federal agency or develop its own analysis in order to
          make its conformity determination.

          51.855   Reporting requirements.

          (a)            A Federal agency making a conformity determination under
               section 51.858 must provide to the appropriate EPA Regional
               Office(s), State and local air quality agencies and, where
               applicable, affected Federal land managers, the agency
               designated under section 174 of the Act and the MPO a 30 day
               notice which describes the proposed action and the Federal
               agency's draft conformity determination on the action.
          (b)  A Federal agency must notify the appropriate EPA Regional
               Office(s), State and local air quality agencies and, where
               applicable, affected Federal land managers, the agency
               designated under section 174 of the Clean Air Act and the
               MPO within 30 days after making a final conformity
               determination under section 51.858.

          51.856   Public participation.

           (a) Upon request by any person regarding a specific Federal
               action, a Federal agency must make available for review its
               draft conformity determination under section 51.858 with
               supporting materials which describe the analytical methods
               and conclusions relied upon in making the applicability
               analysis and draft conformity determination.
          (b)  A Federal agency must make public its draft conformity
               determination under section 51.858 by placing a notice by
               prominent advertisement in a daily newspaper of general
               circulation in the area affected by the action and by
               providing 30 days for written public comment prior to taking
               any formal action on the draft determination.  This comment
               period may be concurrent with any other public involvement,
               such as occurs in the NEPA process.
          (c)  A Federal agency must document its response to all the
               comments received on its draft conformity determination
               under section 51.858 and make the comments and responses
               available, upon request by any person regarding a specific
               Federal action, within 30 days of the final conformity
               determination.
          (d)  A Federal agency must make public its final conformity
               determination under section 51.858 for a Federal action by
               placing a notice by prominent advertisement in a daily
               newspaper of general circulation in the area affected by the
               action within 30 days of the final conformity determination.

          51.857   Frequency of conformity determinations.

          (a)  The conformity status of a Federal action automatically
               lapses 5 years from the date a final conformity
               determination is reported under section 51.855, unless the
               Federal action has been completed or a continuous program
               has been commenced to implement that Federal action within a
               reasonable time.
          (b)  Ongoing Federal activities at a given site showing
               continuous progress are not new actions and do not require
               periodic redeterminations so long as such activities are
               within the scope of the final conformity determination
               reported under section 51.855.
          (c)  If, after the conformity determination is made, the Federal
               action is changed so that there is an increase in the total
               of direct and indirect emissions above the levels in section
               51.853(b), a new conformity determination is required.

          51.858   Criteria for determining conformity of general Federal
                    actions.

          (a)  An action required under section 51.853 to have a conformity
               determination for a specific pollutant, will be determined
               to conform to the applicable SIP if, for each pollutant that
               exceeds the rates in section 51.853, paragraph (b), or
               otherwise requires a conformity determination due to the
               total of direct and indirect emissions from the action, the
               action meets the requirements of paragraph (c) of this
               section, and meets any of the following requirements:
               (1)  For any criteria pollutant, the total of direct and
                    indirect emissions from the action are specifically
                    identified and accounted for in the applicable SIP's
                    attainment or maintenance demonstration;
               (2)  For ozone or nitrogen dioxide, the total of direct and
                    indirect emissions from the action are fully offset
                    within the same nonattainment or maintenance area
                    through a revision to the applicable SIP or a similarly
                    enforceable measure that effects emission reductions so
                    that there is no net increase in emissions of that
                    pollutant;
               (3)  For any criteria pollutant, except ozone and nitrogen
                    dioxide, the total of direct and indirect emissions
                    from the action meet the requirements:
                    (i)  specified in paragraph (b) of this section, based
                         on areawide air quality modeling analysis and
                         local air quality modeling analysis, or
                    (ii) meet the requirements of paragraph (a)(5) and, for
                         local air quality modeling analysis, the
                         requirement of paragraph (b) of this section;
               (4)  For CO or PM-10,
                    (i)  Where the State agency primarily responsible for
                         the applicable SIP determines that an areawide air
                         quality modeling analysis is not needed, the total
                         of direct and indirect emissions from the action
                         meet the requirements specified in  paragraph (b)
                         of this section, based on local air quality
                         modeling analysis or
                    (ii) Where the State agency primarily responsible for
                         the applicable SIP determines that an areawide air
                         quality modeling analysis is appropriate and that
                         a local air quality modeling analysis is not
                         needed, the total of direct and indirect emissions
                         from the action meet the requirements specified in
                         paragraph (b) of this section, based on areawide
                         modeling, or meet the requirements of paragraph
                         (a)(5) of this section; or
               (5)  For ozone or nitrogen dioxide, and for purposes of
                    paragraphs (a)(3)(ii) and (a)(4)(ii) of this section,
                    each portion of the action or the action as a whole
                    meets any of the following requirements:
                    (i)  Where EPA has approved a revision to an area's
                         attainment or maintenance demonstration after 1990
                         and the State makes a determination as provided in
                         paragraph (A) or where the State makes a
                         commitment as provided in paragraph (B):
                         (A)  The total of direct and indirect emissions
                              from the action (or portion thereof) is
                              determined and documented by the State agency
                              primarily responsible for the applicable SIP
                              to result in a level of emissions which,
                              together with all other emissions in the
                              nonattainment (or maintenance) area, would
                              not exceed the emissions budgets specified in
                              the applicable SIP.
                         (B)  The total of direct and indirect emissions
                              from the action (or portion thereof) is
                              determined by the State agency responsible
                              for the applicable SIP to result in a level
                              of emissions which, together with all other
                              emissions in the nonattainment (or
                              maintenance) area, would exceed an emissions
                              budget specified in the applicable SIP and
                              the State Governor or the Governor's designee
                              for SIP actions makes a written commitment to
                              EPA which includes the following:
                              (1)  A specific schedule for adoption and
                                   submittal of a revision to the SIP which
                                   would achieve the needed emission
                                   reductions prior to the time emissions
                                   from the Federal action would occur;
                              (2)  Identification of specific measures for
                                   incorporation into the SIP which would
                                   result in a level of emissions which,
                                   together with all other emissions in the
                                   nonattainment or maintenance area, would
                                   not exceed any emissions budget
                                   specified in the applicable SIP;
                              (3)  A demonstration that all existing
                                   applicable SIP requirements are being
                                   implemented in the area for the
                                   pollutants affected by the Federal
                                   action, and that local authority to
                                   implement additional requirements has
                                   been fully pursued;
                              (4)  A determination that the responsible
                                   Federal agencies have required all
                                   reasonable mitigation measures
                                   associated with their action; and
                              (5)  Written documentation including all air
                                   quality analyses supporting the
                                   conformity determination.
                         (C)  Where a Federal agency made a conformity
                              determination based on a State commitment
                              under subparagraph (a)(5)(i)(B) of this
                              paragraph, such a State commitment is
                              automatically deemed a call for a SIP
                              revision by EPA under section 110(k)(5) of
                              the Act, effective on the date of the Federal
                              conformity determination and requiring
                              response within 18 months or any shorter time
                              within which the State commits to revise the
                              applicable SIP;
                    (ii) The action (or portion thereof), as determined by
                         the MPO, is specifically included in a current
                         transportation plan and transportation improvement
                         program which have been found to conform to the
                         applicable SIP under 40 CFR part 51, subpart T, or
                         40 CFR part 93, subpart A;
                    (iii)     The action (or portion thereof) fully offsets
                              its emissions within the same nonattainment
                              or maintenance area through a revision to the
                              applicable SIP or an equally enforceable
                              measure that effects emission reductions
                              equal to or greater than the total of direct
                              and indirect emissions from the action so
                              that there is no net increase in emissions of
                              that pollutant;
                    (iv) Where EPA has not approved a revision to the
                         relevant SIP attainment or maintenance
                         demonstration since 1990, the total of direct and
                         indirect emissions from the action for the future
                         years [described in paragraph (d) of section
                         51.859] do not increase emissions with respect to
                         the baseline emissions;
                         (A)  The baseline emissions reflect the historical
                              activity levels that occurred in the
                              geographic area affected by the proposed
                              Federal action during:
                              (1)  Calendar year 1990,
                              (2)  The calendar year that is the basis for
                                   the classification (or, where the
                                   classification is based on multiple
                                   years, the most representative year), if
                                   a classification is promulgated in 40
                                   CFR part 81, or
                              (3)  The year of the baseline inventory in
                                   the PM-10 applicable SIP;
                         (B)  The baseline emissions are the total of
                              direct and indirect emissions calculated for
                              the future years [described in paragraph (d)
                              of section 51.859] using the historic
                              activity levels [described in subparagraph
                              (a)(5)(iv)(A) of this paragraph] and
                              appropriate emission factors for the future
                              years; or
                    (v)  Where the action involves regional water and/or
                         wastewater projects, such projects are sized to
                         meet only the needs of population projections that
                         are in the applicable SIP.
          (b)  The areawide and/or local air quality modeling analyses
               must:
               (1)  Meet the requirements in section 51.859 and
               (2)  Show that the action does not:
                    (i)  Cause or contribute to any new violation of any
                         standard in any area; or
                    (ii) Increase the frequency or severity of any existing
                         violation of any standard in any area.
          (c)  Notwithstanding any other requirements of this section, an
               action subject to this subpart may not be determined to
               conform to the applicable SIP unless the total of direct and
               indirect emissions from the action is in compliance or
               consistent with all relevant requirements and milestones
               contained in the applicable SIP, such as elements identified
               as part of the reasonable further progress schedules,
               assumptions specified in the attainment or maintenance
               demonstration, prohibitions, numerical emission limits, and
               work practice requirements.
          (d)  Any analyses required under this section must be completed,
               and any mitigation requirements necessary for a finding of
               conformity must be identified before the determination of
               conformity is made.
          
          51.859   Procedures for conformity determinations of general
                    Federal actions.

          (a)  The analyses required under this subpart must be based on
               the latest planning assumptions.
               (1)  All planning assumptions must be derived from the
                    estimates of population, employment, travel, and
                    congestion most recently approved by the MPO, or other
                    agency authorized to make such estimates, where
                    available.
               (2)  Any revisions to these estimates used as part of the
                    conformity determination, including projected shifts in
                    geographic location or level of population, employment,
                    travel, and congestion, must be approved by the MPO or
                    other agency authorized to make such estimates for the
                    urban area.
          (b)  The analyses required under this subpart must be based on
               the latest and most accurate emission estimation techniques
               available as described below, unless such techniques are
               inappropriate.  If such techniques are inappropriate and
               written approval of the EPA Regional Administrator is
               obtained for any modification or substitution, they may be
               modified or another technique substituted on a case-by-case
               basis or, where appropriate, on a generic basis for a
               specific Federal agency program.
               (1)  For motor vehicle emissions, the most current version
                    of the motor vehicle emissions model specified by EPA
                    and available for use in the preparation or revision of
                    SIPs in that State must be used for the conformity
                    analysis as specified below:
                    (i)  The EPA must publish in the Federal Register a
                         notice of availability of any new motor vehicle
                         emissions model; and
                    (ii) A grace period of three months shall apply during
                         which the motor vehicle emissions model previously
                         specified by EPA as the most current version may
                         be used.  Conformity analyses for which the
                         analysis was begun during the grace period or no
                         more than 3 years before the Federal Register
                         notice of availability of the latest emission
                         model may continue to use the previous version of
                         the model specified by EPA.
               (2)  For non-motor vehicle sources, including stationary and
                    area source emissions, the latest emission factors
                    specified by EPA in the "Compilation of Air Pollutant
                    Emission  Factors (AP-42)" must be used for the
                    conformity analysis unless more accurate emission data
                    are available, such as actual stack test data from
                    stationary sources which are part of the conformity
                    analysis.
          (c)  The air quality modeling analyses required under this
               Subpart must be based on the applicable air quality models,
               data bases, and other requirements specified in the most
               recent version of the "Guideline on Air Quality Models
               (Revised)" (1986), including supplements (EPA publication
               no. 450/2-78-027R),  unless:
               (1)  The guideline techniques are inappropriate, in which
                    case the model may be modified or another model
                    substituted on a case-by-case basis or, where
                    appropriate, on a generic basis for a specific Federal
                    agency program; and
               (2)  Written approval of the EPA Regional Administrator is
                    obtained for any modification or substitution.
          (d)  The analyses required under this subpart, except section
               51.858, paragraph (a)(1), must be based on the total of
               direct and indirect emissions from the action and must
               reflect emission scenarios that are expected to occur under
               each of the following cases:
               (1)  The Act mandated attainment year or, if applicable, the
                    farthest year for which emissions are projected in the
                    maintenance plan;
               (2)  The year during which the total of direct and indirect
                    emissions from the action is expected to be the
                    greatest on an annual basis; and
               (3)  Any year for which the applicable SIP specifies an
                    emissions budget.

          51.860   Mitigation of air quality impacts.

          (a)  Any measures that are intended to mitigate air quality
               impacts must be identified and the process for
               implementation and enforcement of such measures must be
               described, including an implementation schedule containing
               explicit timelines for implementation.
          (b)  Prior to determining that a Federal action is in conformity,
               the Federal agency making the conformity determination must
               obtain written commitments from the appropriate persons or
               agencies to implement any mitigation measures which are
               identified as conditions for making conformity
               determinations.
          (c)  Persons or agencies voluntarily committing to mitigation
               measures to facilitate positive conformity determinations
               must comply with the obligations of such commitments.
          (d)  In instances where the Federal agency is licensing,
               permitting or otherwise approving the action of another
               governmental or private entity, approval by the Federal
               agency must be conditioned on the other entity meeting the
               mitigation measures set forth in the conformity
               determination.
          (e)  When necessary because of changed circumstances, mitigation
               measures may be modified so long as the new mitigation
               measures continue to support the conformity determination.
               Any proposed change in the mitigation measures is subject to
               the reporting requirements of section 51.856 and the public
               participation requirements of section 51.857.
          (f)  The implementation plan revision required in section 51.851
               of this subpart shall provide that written commitments to
               mitigation measures must be obtained prior to a positive
               conformity determination and that such commitments must be
               fulfilled.
          (g)  After a State revises its SIP to adopt its general
               conformity rules and EPA approves that SIP revision, any
               agreements, including mitigation measures, necessary for a
               conformity determination will be both State and federally
               enforceable.  Enforceability through the applicable SIP will
               apply to all persons who agree to mitigate direct and
               indirect emissions associated with a Federal action for a
               conformity determination.
          PART 93 -- DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR
          FEDERAL IMPLEMENTATION PLANS
          SUBPART B -- DETERMINING CONFORMITY OF GENERAL FEDERAL ACTIONS TO
          STATE  OR FEDERAL IMPLEMENTATION PLANS
          Sec.
          93.150    Prohibition.
          93.151    State implementation plan (SIP) revision.
          93.152    Definitions.
          93.153    Applicability.
          93.154    Conformity analysis.
          93.155    Reporting requirements.
          93.156    Public participation.
          93.157    Frequency of conformity determinations.
          93.158    Criteria for determining conformity of general Federal
                    actions.
          93.159    Procedures for conformity determinations of general
                    Federal actions.
          93.160    Mitigation of air quality impacts.

          SUBPART B -- DETERMINING CONFORMITY OF GENERAL FEDERAL ACTIONS TO
          STATE  OR FEDERAL IMPLEMENTATION PLANS

          93.150   Prohibition.

          (a)  No department, agency or instrumentality of the Federal
               Government shall engage in, support in any way or provide
               financial assistance for, license or permit, or approve any
               activity which does not conform to an applicable
               implementation plan.
          (b)  A Federal agency must make a determination that a Federal
               action conforms to the applicable implementation plan in
               accordance with the requirements of this rule before the
               action is taken.
          (c)  The preceding sentence does not include Federal actions
               where:
               (1)  A National Environmental Policy Act (NEPA) analysis was
                    completed as evidenced by a final environmental
                    assessment (EA), environmental impact statement (EIS),
                    or finding of no significant impact (FONSI) that was
                    prepared prior to the effective date of this rule, or
               (2)  (i)  Prior to the effective date of this rule, an
                         environmental analysis was commenced or a contract
                         was awarded to develop the specific environmental
                         analysis,
                    (ii) Sufficient environmental analysis is completed by
                         March 15, 1994 so that the Federal agency may
                         determine that the Federal action is in conformity
                         with the sp ecific requirements and the purposes
                         of the applicable SIP pursuant to the agency's
                         affirmative obligation under section 176(c) of the
                         Clean Air Act (Act), and
                    (iii)     A written determination of conformity under
                              section 176(c) of the Act has been made by
                              the Federal agency responsible for the
                              Federal action by March 15, 1994, or
          (d)  Notwithstanding any provision of this subpart, a
               determination that an action is in conformance with the
               applicable implementation plan does not exempt the action
               from any other requirements of the applicable implementation
               plan, the National Environmental Policy Act (NEPA), or the
               Clean Air Act (Act).

          93.151   State implementation plan (SIP) revision.

          The Federal conformity rules under this Subpart, in addition to any
          existing applicable State requirements, establish the conformity
          criteria and procedures necessary to meet the Act requirements
          until such time as the required conformity SIP revision is
          approved by EPA.  A State's conformity provisions must contain
          criteria and procedures that are no less stringent than the
          requirements described in this subpart.  A State may establish
          more stringent conformity criteria and procedures only if they
          apply equally to nonfederal as well as Federal entities.
          Following EPA approval of the State conformity provisions (or a
          portion thereof) in a revision to the applicable SIP, the
          approved (or approved portion of the) State criteria and
          procedures would govern conformity determinations and the Federal
          conformity regulations contained in 40 CFR part 93 would apply
          only for the portion, if any, of the State's conformity
          provisions that is not approved by EPA.  In addition, any
          previously applicable SIP requirements relating to conformity
          remain enforceable until the State revises its SIP to
          specifically remove them from the SIP and that revision is
          approved by EPA.

          93.152   Definitions.

          Terms used but not defined in this part shall have the meaning 
          given them by the Act and EPA's regulations, in that order of 
          priority.  Affected Federal land manager means the Federal 
          agency or the Federal official charged with direct responsibility 
          for  management of an area designated as Class I under 42 U.S.C.
          7472 of the Act that is located within 100 km of the proposed 
          Federal action. Applicable implementation plan or applicable SIP 
          means the portion (or portions) of the SIP or most recent revision
          thereof, which has been approved under section 110 of the
          Act, or promulgated under section 110(c) of the Act (Federal
          implementation plan), or promulgated or approved pursuant to
          regulations promulgated under section 301(d) of the Act and
          which implements the relevant requirements of the Act.
          Areawide air quality modeling analysis means an assessment
          on a scale that includes the entire nonattainment or
          maintenance area which uses an air quality dispersion model
          to determine the effects of emissions on air quality.
          Cause or contribute to a new violation means a Federal
          action that:
               (1)  Causes a new violation of a national ambient air
                    quality standard (NAAQS) at a location in a
                    nonattainment or maintenance area which would otherwise
                    not be in violation of the standard during the future
                    period in question if the Federal action were not
                    taken, or
               (2)  Contributes, in conjunction with other reasonably
                    foreseeable actions, to a new violation of a NAAQS at a
                    location in a nonattainment or maintenance area in a
                    manner that would increase the frequency or severity of
                    the new violation.
               Caused by, as used in the terms "direct emissions" and
               "indirect emissions," means emissions that would not
               otherwise occur in the absence of the Federal action.
               Criteria pollutant or standard means any pollutant for which
               there is established a NAAQS at 40 CFR part 50.
               Direct emissions means those emissions of a criteria
               pollutant or its precursors that are caused or initiated by
               the Federal action and occur at the same time and place as
               the action.
               Emergency means a situation where extremely quick action on
               the  part of the Federal agencies involved is needed and
               where the timing of such Federal activities makes it
               impractical to meet the requirements of this rule, such as
               natural disasters like hurricanes or earthquakes, civil
               disturbances such as terrorist acts. and military
               mobilizations.
               Emissions budgets are those portions of the applicable SIP's
               projected emission inventories that describe the levels of
               emissions (mobile, stationary, area, etc.) that provide for
               meeting reasonable further progress milestones, attainment,
               and/or maintenance for any criteria pollutant or its
               precursors.
               Emission offsets, for purposes of section 93.158, are
               emissions reductions which are quantifiable, consistent with
               the applicable SIP attainment and reasonable further
               progress demonstrations, surplus to reductions required by,
               and credited to, other applicable SIP provisions,
               enforceable at both the State and Federal levels, and
               permanent within the timeframe specified by the program.
               Emissions that a Federal agency has a continuing program
               responsiblity for means emissions that are specifically
               caused by an agency carrying out its authorities, and does
               not include emissions that occur due to subsequent
               activities, unless such activities are required by the
               Federal agency.  When an agency, in performing its normal
               program responsibilities, takes actions itself or imposes
               conditions that result in air pollutant emissions by a non-
               Federal entity taking subsequent actions, such emissions are
               covered by the meaning of a continuing program
               responsibility.
               EPA means the Environmental Protection Agency.
               Federal action means any activity engaged in by a
               department, agency, or instrumentality of the Federal
               government, or any activity that a department, agency or
               instrumentality of the Federal government supports in any
               way, provides financial assistance for, licenses, permits,
               or approves, other than activities related to transportation
               plans, programs, and projects developed, funded, or approved
               under title 23 U.S.C. or the Federal Transit Act (49 U.S.C.
               1601 et seq.).  Where the Federal action is a permit,
               license, or other approval for some aspect of a non-Federal
               undertaking, the relevant activity is the part, portion, or
               phase of the non-Federal undertaking that requires the
               Federal permit, license, or approval.
               Federal agency means, for purposes of this rule, a Federal
               department, agency, or instrumentality of the Federal
               government.
               Increase the frequency or severity of any existing violation
               of any standard in any area means to cause a nonattainment
               area to exceed a standard more often or to cause a violation
               at a greater concentration than previously existed and/or
               would otherwise exist during the future period in question,
               if the project were not implemented.
               Indirect emissions means those emissions of a criteria
               pollutant or its precursors that:
               (1)  Are caused by the Federal action, but may occur later
                    in time and/or may be further removed in distance from
                    the action itself but are still reasonably foreseeable,
                    and
               (2)  The Federal agency can practicably control and will
                    maintain control over due to a continuing program
                    responsibility of the Federal agency.
               Local air quality modeling analysis means an assessment of
               localized impacts on a scale smaller than the entire
               nonattainment or maintenance area, including, for example,
               congested roadway intersections and highways or transit
               terminals, which uses an air quality dispersion model to
               determine the effects of emissions on  air quality.
               Maintenance area means an area with a maintenance plan
               approved under section 175A of the Act.
               Maintenance plan means a revision to the applicable SIP,
               meeting the requirements of section 175A of the Act.
               Metropolitan Planning Organization (MPO) is that
               organization designated as being responsible, together with
               the State, for conducting the continuing, cooperative, and
               comprehensive planning process under 23 U.S.C. 134 and 49
               U.S.C. 1607.
               Milestone has the meaning given in sections 182(g)(1) and
               189(c)(1) of the Act.
               National ambient air quality standards (NAAQS) are those
               standards established pursuant to section 109 of the Act and
               include standards for carbon monoxide (CO), lead (Pb),
               nitrogen dioxide (NO2), ozone, particulate matter (PM-10),
               and sulfur dioxide (SO2).
               NEPA is the National Environmental Policy Act of 1969, as
               amended (42 U.S.C. 4321 et seq.).
               Nonattainment area means an area designated as nonattainment
               under section 107 of the Act and described in 40 CFR part 81.
               Precursors of a criteria pollutant are:
               (1)  For ozone, nitrogen oxides (NOx), unless an area is
                    exempted from NOx requirements under section 182(f) of
                    the Act, and volatile organic compounds (VOC), and
               (2)  For PM-10, those pollutants described in the PM-10
                    nonattainment area applicable SIP as significant
                    contributors to the PM-10 levels.
               Reasonably foreseeable emissions are projected future
               indirect emissions that are identified at the time the
               conformity determination is made; the location of such
               emissions is known and the emissions are quantifiable, as
               described and documented by the Federal agency based on its
               own information and after reviewing any information
               presented to the Federal agency.
               Regionally significant action means a Federal action for
               which the direct and indirect emissions of any pollutant
               represent 10 percent or more of a nonattainment or
               maintenance area's emission inventory for that pollutant.
               Regional water and/or wastewater projects include
               construction, operation, and maintenance of water or
               wastewater conveyances, water or wastewater treatment
               facilities, and water storage reservoirs which affect a
               large portion of a nonattainment or maintenance area.
               Total of direct and indirect emissions means the sum of
               direct and indirect emissions increases and decreases caused
               by the Federal action; i.e., the "net" emissions considering
               all direct and indirect emissions.  The portion of emissions
               which are exempt or presumed to conform under section
               93.153, paragraph (c), (d), (e), or (f) are not included in
               the "total of direct and indirect emissions."  The "total of
               direct and indirect emissions" includes emissions of
               criteria pollutants and emissions of precursors of criteria
               pollutants.

          93.153   Applicability.

          (a)  Conformity determinations for Federal actions related to
               transportation plans, programs, and projects developed,
               funded, or approved under title 23 U.S.C. or the Federal
               Transit Act (49 U.S.C.  1601 et seq.) must meet the
               procedures and criteria of 40 CFR part 51, subpart T, in
               lieu of the procedures set forth in this subpart.
          (b)  For Federal actions not covered by paragraph (a) of this
               section, a conformity determination is required for each
               pollutant where the total of direct and indirect emissions
               in a nonattainment or maintenance area caused by a Federal
               action would equal or exceed any of the rates in paragraphs
               (b)(1) or (2) of this section.
               (1)  For purposes of paragraph (b) of this section, the
                    following rates apply in nonattainment areas (NAA's):
                                               Tons/Year
                         Ozone (VOC's or NOx)
                    Serious NAA's                   50
                    Severe NAA's                    25
                    Extreme NAA's                   10
                    Other ozone NAA's outside an
                      ozone transport region       100
                    Marginal and moderate NAA's
                      inside an ozone transport region
                         VOC                        50
                         NOx                       100
               Carbon monoxide
                         All NAA's                 100
               SO2 or NO2
                         All NAA's                 100
               PM-10
                         Moderate NAA's            100
                    Serious NAA's                   70
               Pb
                         All NAA's                  25

               (2)  For purposes of paragraph (b) of this section, the
                    following rates apply in maintenance areas:
                                                   Tons/Year
               Ozone (NOx), SO2 or NO2
                         All Maintenance Areas         100
               Ozone (VOC's)
                              Maintenance areas inside
                      an ozone transport region         50
                    Maintenance areas outside
                      an ozone transport region        100
               Carbon monoxide
                         All Maintenance Areas         100
               PM-10
                         All Maintenance Areas         100
               Pb
                         All Maintenance Areas          25

          (c)  The requirements of this subpart shall not apply to the
               following Federal actions:
               (1)  Actions where the total of direct and indirect
                    emissions are below the emissions levels specified in
                    paragraph (b) of this section.
               (2)  Actions which would result in no emissions increase or
                    an increase in emissions that is clearly de minimis:
                    (i)  Judicial and legislative proceedings.
                    (ii) Continuing and recurring activities such as permit
                         renewals where activities conducted will be
                         similar in scope and operation to activities
                         currently being  conducted.
                    (iii)     Rulemaking and policy development and
                              issuance.
                    (iv) Routine maintenance and repair activities,
                         including repair and maintenance of administrative
                         sites, roads, trails, and facilities.
                    (v)  Civil and criminal enforcement activities, such as
                         investigations, audits, inspections, examinations,
                         prosecutions, and the training of law enforcement
                         personnel.
                    (vi) Administrative actions such as personnel actions,
                         organizational changes, debt management or
                         collection, cash management, internal agency
                         audits, program budget proposals, and matters
                         relating to the administration and collection of
                         taxes, duties and fees.
                    (vii)     The routine, recurring transportation of
                              materiel and personnel.
                    (viii)    Routine movement of mobile assets, such as
                              ships and aircraft, in home port
                              reassignments and stations (when no new
                              support facilities or personnel are required)
                              to perform as operational groups and/or for
                              repair or overhaul.
                    (ix) Maintenance dredging and debris disposal where no
                         new depths are required, applicable permits are
                         secured, and disposal will be at an approved
                         disposal site.
                    (x)  Actions, such as the following, with respect to
                         existing structures, properties, facilities and
                         lands where future activities conducted will be
                         similar in scope and operation to activities
                         currently being conducted at the existing
                         structures, properties, facilities, and lands; for
                         example, relocation of personnel, disposition of
                         federally-owned existing structures, properties,
                         facilities, and lands, rent subsidies, operation
                         and maintenance cost subsidies, the exercise of
                         receivership or conservatorship authority,
                         assistance in purchasing structures, and the
                         production of coins and currency.
                    (xi) The granting of leases, licenses such as for
                         exports and trade, permits, and easements where
                         activities conducted will be similar in scope and
                         operation to activities currently being conducted.
                    (xii)     Planning, studies, and provision of technical
                              assistance.
                    (xiii)    Routine operation of facilities, mobile
                              assets and equipment.
                    (xiv)     Transfers of ownership, interests, and titles
                              in land, facilities, and real and personal
                              properties, regardless of the form or method
                              of the transfer.
                    (xv) The designation of empowerment zones, enterprise
                         communities, or viticultural areas.
                    (xvi)     Actions by any of the Federal banking
                              agencies or the Federal Reserve Banks,
                              including actions regarding charters,
                              applications, notices, licenses, the
                              supervision or examination of depository
                              institutions or depository institution
                              holding companies, access to the discount
                              window, or the provision of financial
                              services to banking organizations or to any
                              department, agency or instrumentality of the
                              United States.
                    (xvii)    Actions by the Board of Governors of the
                              Federal Reserve System or any Federal Reserve
                              Bank necessary to effect monetary or exchange
                              rate policy.
                    (xviii)   Actions that implement a foreign affairs
                              function of the United States.
                    (xix)     Actions (or portions thereof) associated with
                              transfers of land, facilities, title, and
                              real properties through an enforceable
                              contract or lease agreement where the
                              delivery of the deed is required to occur
                              promptly after a specific, reasonable
                              condition is met, such as promptly after the
                              land is certified as meeting the requirements
                              of CERCLA, and where the Federal agency does
                              not retain continuing authority to control
                              emissions associated with the lands,
                              facilities, title, or real properties.
                    (xx) Transfers of real property, including land,
                         facilities, and related personal property from a
                         Federal entity to another Federal entity and
                         assignments of real property, including land,
                         facilities, and related personal property from a
                         Federal entity to another Federal entity for
                         subsequent deeding to eligible applicants.
                    (xxi)     Actions by the Department of the Treasury to
                              effect fiscal policy and to exercise the
                              borrowing authority of the United States.
               (3)  Actions where the emissions are not reasonably
                    foreseeable, such as the following:
                    (i)  Initial Outer Continental Shelf lease sales which
                         are made on a broad scale and are followed by
                         exploration and development plans on a project
                         level.
                    (ii) Electric power marketing activities that involve
                         the acquisition, sale and transmission of electric
                         energy.
               (4)  Actions which implement a decision to conduct or carry
                    out a conforming program such as prescribed burning
                    actions which are consistent with a conforming land
                    management plan.
          (d)  Notwithstanding the other requirements of this subpart, a
               conformity determination is not required for the following
               Federal actions (or portion thereof):
               (1)  The portion of an action that includes major new or
                    modified stationary sources that require a permit under
                    the new source review (NSR) program (section 173 of the
                    Act) or the prevention of significant deterioration
                    program (title I, part C of the Act).
               (2)  Actions in response to emergencies or natural disasters
                    such as hurricanes, earthquakes, etc., which are
                    commenced on the order of hours or days after the
                    emergency or disaster and, if applicable, which meet
                    the requirements of paragraph (e) of this section;
               (3)  Research, investigations, studies, demonstrations, or
                    training (other than those exempted under section
                    51.853(c)(2)), where no environmental detriment is
                    incurred and/or, the particular action furthers air
                    quality research, as determined by the State agency
                    primarily responsible for the applicable SIP;
               (4)  Alteration and additions of existing structures as
                    specifically required by new or existing applicable
                    environmental legislation or environmental regulations
                    (e.g., hush houses for aircraft engines and scrubbers
                    for air emissions).
               (5)  Direct emissions from remedial and removal actions
                    carried out under the Comprehensive Environmental
                    Response, Compensation and Liability Act and associated
                    regulations to the extent such emissions either comply
                    with the substantive requirements of the PSD/NSR
                    permitting program or are exempted from other
                    environmental regulation under the provisions of CERCLA
                    and applicable regulations issued under CERCLA.
          (e)  Federal actions which are part of a continuing response to
               an emergency or disaster under section 93.153(d)(2) and
               which are to be taken more than 6 months after the
               commencement of the response to the emergency or disaster
               under section 93.153(d)(2) are exempt from the requirements
               of this subpart only if:
               (1)  The Federal agency taking the actions makes a written
                    determination that, for a specified period not to
                    exceed an additional 6 months, it is impractical to
                    prepare the conformity analyses which would otherwise
                    be required and the actions cannot be delayed due to
                    overriding concerns for public health and welfare,
                    national security interests and foreign policy
                    commitments; or
               (2)  For actions which are to be taken after those actions
                    covered by paragraph (e)(1) of this section, the
                    Federal agency makes a new determination as provided in
                    paragraph (e)(1) of this section.
          (f)  Notwithstanding other requirements of this subpart, actions
               specified by individual Federal agencies that have met the
               criteria set forth in either paragraph (g)(1) or (g)(2) and
               the procedures set forth in paragraph (h) of this section
               are presumed to conform, except as provided in paragraph (j)
               of this section.
          (g)  The Federal agency must meet the criteria for establishing
               activities that are presumed to conform by fulfilling the
               requirements set forth in either paragraph (g)(1) or (g)(2)
               of this section:
               (1)  The Federal agency must clearly demonstrate using
                    methods consistent with this rule that the total of
                    direct and indirect emissions from the type of
                    activities which would be  presumed to conform would
                    not:
                    (i)  Cause or contribute to any new violation of any
                         standard in any area;
                    (ii) Interfere with provisions in the applicable SIP
                         for maintenance of any standard;
                    (iii)     Increase the frequency or severity of any
                              existing violation of any standard in any
                              area; or
                    (iv) Delay timely attainment of any standard or any
                         required interim emission reductions or other
                         milestones in any area including, where
                         applicable, emission levels specified in the
                         applicable SIP for purposes of:
                         (A)  A demonstration of reasonable further
                              progress;
                         (B)  A demonstration of attainment; or
                         (C)  A maintenance plan; or
               (2)  The Federal agency must provide documentation that the
                    total of direct and indirect emissions from such future
                    actions would be below the emission rates for a
                    conformity  determination that are established in
                    paragraph (b) of this section, based, for example, on
                    similar actions taken over recent years.

          (h)  In addition to meeting the criteria for establishing
               exemptions set forth in paragraphs (g)(1) or (g)(2) of this
               section, the following procedures must also be complied with
               to presume that activities will conform:
               (1)  The Federal agency must identify through publication in
                    the Federal Register its list of proposed activities
                    that are presumed to conform and the basis for the
                    presumptions;
               (2)  The Federal agency must notify the appropriate EPA
                    Regional Office(s), State and local air quality
                    agencies and, where applicable, the agency designated
                    under section 174 of the Act and the MPO and provide at
                    least 30 days for the public to comment on the list of
                    proposed activities presumed to conform;
               (3)  The Federal agency must document its response to all
                    the comments received and make the comments, response,
                    and final list of activities available to the public
                    upon request; and
               (4)  The Federal agency must publish the final list of such
                    activities in the Federal Register.
          (i)  Notwithstanding the other requirements of this subpart, when
               the total of direct and indirect emissions of any pollutant
               from a Federal action does not equal or exceed the rates
               specified in paragraph (b) of this section, but represents
               10 percent or more of a nonattainment or maintenance area's
               total emissions of that pollutant, the action is defined as
               a regionally significant action and the requirements of
               section 93.150 and sections 93.155-860 shall apply for the
               Federal action.
          (j)  Where an action otherwise presumed to conform under
               paragraph (f) of this section is a regionally significant
               action or does not in fact meet one of the criteria in
               paragraph (g)(1) of this section, that action shall not be
               presumed to conform and the requirements of section 93.150
               and sections 93.155-860 shall apply for the Federal action.
          (k)  The provisions of this subpart shall apply in all
               nonattainment and maintenance areas.

          93.154   Conformity analysis.

          Any Federal department, agency, or instrumentality of the Federal
          government taking an action subject to this subpart must make its
          own conformity determination consistent with the requirements of
          this subpart.  In making its conformity determination, a Federal
          agency must consider comments from any interested parties.  Where
          multiple Federal agencies have jurisdiction for various aspects
          of a project, a Federal agency may choose to adopt the analysis
          of another Federal agency or develop its own analysis in order to
          make its conformity determination.

          93.155   Reporting requirements.

          (a)  A Federal agency making a conformity determination under
               section 93.158 must provide to the appropriate EPA Regional
               Office(s), State and local air quality agencies and, where
               applicable, affected Federal land managers, the agency
               designated under section 174 of the Act and the MPO a 30 day
               notice which describes the proposed action and the Federal
               agency's draft conformity determination on the action.
          (b)  A Federal agency must notify the appropriate EPA Regional
               Office(s), State and local air quality agencies and, where
               applicable, affected Federal land managers, the agency
               designated under section 174 of the Clean Air Act and the
               MPO within 30 days after making a final conformity
               determination under section 93.158.

          93.156   Public participation.

          (a)  Upon request by any person regarding a specific Federal
               action, a Federal agency must make available for review its
               draft conformity determination under section 93.158 with
               supporting materials which describe the analytical methods
               and conclusions relied upon in making the applicability
               analysis and draft conformity determination.
          (b)  A Federal agency must make public its draft conformity
               determination under section 93.158 by placing a notice by
               prominent advertisement in a daily newspaper of general
               circulation in the area affected by the action and by
               providing 30 days for written public comment prior to taking
               any formal action on the draft determination.  This comment
               period may be concurrent with any other public involvement,
               such as occurs in the NEPA process.
          (c)  A Federal agency must document its response to all the
               comments received on its draft conformity determination
               under section 93.158 and make the comments and responses
               available, upon request by any person regarding a specific
               Federal action, within 30 days of the final conformity
               determination.
          (d)  A Federal agency must make public its final conformity
               determination under section 93.158 for a Federal action by
               placing a notice by prominent advertisement in a daily
               newspaper of general circulation in the area affected by the
               action within 30 days of the final conformity determination.

          93.157   Frequency of conformity determinations.

          (a)  The conformity status of a Federal action automatically
               lapses 5 years from the date a final conformity
               determination is reported under section 93.155, unless the
               Federal action has been completed or a continuous program
               has been commenced to implement that Federal action within a
               reasonable time.
          (b)  Ongoing Federal activities at a given site showing
               continuous progress are not new actions and do not require
               periodic redeterminations so long as such activities are
               within the scope of the final conformity determination
               reported under section 93.155.
          (c)  If, after the conformity determination is made, the Federal
               action is changed so that there is an increase in the total
               of direct and indirect emissions, above the levels in
               section 93.153(b), a new conformity determination is
               required.

          93.158   Criteria for determining conformity of general Federal
                    actions.

          (a)  An action required under section 93.153 to have a conformity
               determination for a specific pollutant, will be determined
               to conform to the applicable SIP if, for each pollutant that
               exceeds the rates in section 93.153, paragraph (b), or
               otherwise requires a conformity determination due to the
               total of direct and indirect emissions from the action, the
               action meets the requirements of paragraph (c) of this
               section, and meets any of the following requirements:
               (1)  For any criteria pollutant, the total of direct and
                    indirect emissions from the action are specifically
                    identified and accounted for in the applicable SIP's
                    attainment or maintenance demonstration;
               (2)  For ozone or nitrogen dioxide, the total of direct and
                    indirect emissions from the action are fully offset
                    within the same nonattainment or maintenance area
                    through a revision to the applicable SIP or a similarly
                    enforceable measure that effects emission reductions so
                    that there is no net increase in emissions of that
                    pollutant;
               (3)  For any criteria pollutant, except ozone and nitrogen
                    dioxide, the total of direct and indirect emissions
                    from the action meet the requirements:
                    (i)  Specified in paragraph (b) of this section, based
                         on areawide air quality modeling analysis and
                         local air quality modeling analysis, or
                    (ii) Meet the requirements of paragraph (a)(5) and, for
                         local air quality modeling analysis, the
                         requirement of paragraph (b) of this section;
               (4)  For CO or PM-10,
                    (i)  Where the State agency primarily responsible for
                         the applicable SIP determines that an areawide air
                         quality modeling analysis is not needed, the total
                         of direct and indirect emissions from the action
                         meet the requirements specified in paragraph (b)
                         of this section, based on local air quality
                         modeling analysis or
                    (ii) Where the State agency primarily responsible for
                         the applicable SIP determines that an areawide air
                         quality modeling analysis is appropriate and that
                         a local air quality modeling analysis is not
                         needed, the total of direct and indirect emissions
                         from the action meet the requirements specified in
                         paragraph (b) of this section, based on areawide
                         modeling, or meet the requirements of paragraph
                         (a)(5) of this section; or
               (5)  For ozone or nitrogen dioxide, and for purposes of
                    paragraphs (a)(3)(11) and (a)(4)(ii) of this section,
                    each portion of the action or the action as a whole
                    meets any of the following requirements:
                    (i)  Where EPA has approved a revision to an area's
                         attainment or maintenance demonstration after 1990
                         and the State makes a determination as provided in
                         paragraph (A) or where the State makes a
                         commitment as provided in paragraph (B):
                         (A)  The total of direct and indirect emissions
                              from the action (or portion thereof) is
                              determined and documented by the State agency
                              primarily responsible for the applicable SIP
                              to result in a level of emissions which,
                              together with all other emissions in the
                              nonattainment (or maintenance) area, would
                              not exceed the emissions budgets specified in
                              the applicable SIP.
                         (B)  The total of direct and indirect emissions
                              from the action (or portion thereof) is
                              determined by the State agency responsible
                              for the applicable SIP to result in a level
                              of emissions which, together with all other
                              emissions in the nonattainment (or
                              maintenance) area, would exceed an emissions
                              budget specified in the applicable SIP and
                              the State  Governor or the Governor's
                              designee for SIP actions makes a written
                              commitment to EPA which includes the
                              following:
                              (1)  A specific schedule for adoption and
                                   submittal of a revision to the SIP which
                                   would achieve the needed emission
                                   reductions prior to the time emissions
                                   from the Federal action would occur;
                              (2)  Identification of specific measures for
                                   incorporation into the SIP which would
                                   result in a level of emissions which,
                                   together with all other emissions in the
                                   nonattainment or maintenance area, would
                                   not exceed any emissions budget
                                   specified in the applicable SIP;
                              (3)  A demonstration that all existing
                                   applicable SIP requirements are being
                                   implemented in the area for the
                                   pollutants affected by the Federal
                                   action, and that local authority to
                                   implement additional requirements has
                                   been fully pursued;
                              (4)  A determination that the responsible
                                   Federal agencies have required all
                                   reasonable mitigation measures
                                   associated with their action; and
                              (5)  Written documentation including all air
                                   quality analyses supporting the
                                   conformity determination.
                         (C)  Where a Federal agency made a conformity
                              determination based on a State commitment
                              under subparagraph (a)(5)(i)(B) of this
                              paragraph, such a State commitment is
                              automatically deemed a call for a SIP
                              revision by EPA under section 110(k)(5) of
                              the Act, effective on the date of the Federal
                              conformity determination and requiring
                              response within 18 months or any shorter time
                              within which the State commits to revise the
                              applicable SIP;
                    (ii) The action (or portion thereof), as determined by
                         the MPO, is specifically included in a current
                         transportation plan and transportation improvement
                         program which have been found to conform to the
                         applicable SIP under 40 CFR part 51, subpart T, or
                         40 CFR part 93, subpart A;
                    (iii)     The action (or portion thereof) fully offsets
                              its emissions within the same nonattainment
                              or maintenance area through a revision to the
                              applicable SIP or an equally enforceable
                              measure that effects emission reductions
                              equal to or greater than the total of direct
                              and indirect emissions from the action so
                              that there is no net increase in emissions of
                              that pollutant;
                    (iv) Where EPA has not approved a revision to the
                         relevant SIP attainment or maintenance
                         demonstration since 1990, the total of direct and
                         indirect emissions from the action for the future
                         years [described in paragraph (d) of section
                         93.159] do not increase emissions with respect to
                         the baseline emissions;
                         (A)  The baseline emissions reflect the historical
                              activity levels that occurred in the
                              geographic area affected by the proposed
                              Federal  action during:
                              (1)  Calendar year 1990,
                              (2)  The calendar year that is the basis for
                                   the classification (or, where the
                                   classification is based on multiple
                                   years, the most representative year), if
                                   a classification is promulgated in 40
                                   CFR part 81, or
                              (3)  The year of the baseline inventory in
                                   the PM-10 applicable SIP;
                         (B)  The baseline emissions are the total of
                              direct and indirect emissions calculated for
                              the future years [described in paragraph (d)
                              of section 93.159] using the historic
                              activity levels [described in subparagraph
                              (a)(5)(iv)(A) of this paragraph] and
                              appropriate emission factors for the future
                              years; or
                    (v)  Where the action involves regional water and/or
                         wastewater projects, such projects are sized to
                         meet only the needs of population projections that
                         are in the applicable SIP.
          (b)  The areawide and/or local air quality modeling analyses
               must:
               (1)  Meet the requirements in section 93.159 and
               (2)  Show that the action does not:
                    (i)  Cause or contribute to any new violation of any
                         standard in any area; or
                    (ii) Increase the frequency or severity of any existing
                         violation of any standard in any area.
          (c)  Notwithstanding any other requirements of this section, an
               action subject to this subpart may not be determined to
               conform to the applicable SIP unless the total of direct and
               indirect emissions from the action is in compliance or
               consistent with all relevant requirements and milestones
               contained in the applicable SIP, such as elements identified
               as part of the reasonable further progress schedules,
               assumptions specified in the attainment or maintenance
               demonstration, prohibitions, numerical emission limits, and
               work practice requirements.
          (d)  Any analyses required under this section must be completed,
               and any mitigation requirements necessary for a finding of
               conformity must be identified before the determination of
               conformity is made.

          93.159   Procedures for conformity determinations of general
                    Federal actions.

          (a)       The analyses required under this subpart must be based on
                    the latest planning assumptions. 
               (1) All planning assumptions must be derived from the 
                 estimates of population, employment, travel, and congestion 
                 most recently approved by the MPO, or other agency authorized 
                 to make such estimates, where available.
               (2)  Any revisions to these estimates used as part of the
                    conformity determination, including projected shifts in
                    geographic location or level of population, employment,
                    travel, and congestion, must be approved by the MPO or
                    other agency authorized to make such estimates for the
                    urban area.
          (b)  The analyses required under this subpart must be based on
               the latest and most accurate emission estimation techniques
               available as described below, unless such techniques are
               inappropriate.  If such techniques are inappropriate and
               written approval of the EPA Regional Administrator is
               obtained for any modification or substitution, they may be
               modified or another technique substituted on a case-by-case
               basis or, where appropriate, on a generic basis for a
               specific Federal agency program.
               (1)  For motor vehicle emissions, the most current version
                    of the motor vehicle emissions model specified by EPA
                    and available for use in the preparation or revision of
                    SIPs in that State must be used for the conformity
                    analysis as specified below:
                    (i)  The EPA must publish in the Federal Register a
                         notice of availability of any new motor vehicle
                         emissions model; and
                    (ii) A grace period of 3 months shall apply during
                         which the motor vehicle emissions model previously
                         specified by EPA as the most current version may
                         be used.  Conformity analyses for which the
                         analysis was begun during the grace period or no
                         more than 3 years before the Federal Register
                         notice of availability of the latest emission
                         model may continue to use the previous version of
                         the model specified by EPA.
               (2)  For non-motor vehicle sources, including stationary and
                    area source emissions, the latest emission factors
                    specified by EPA in the "Compilation of Air Pollutant
                    Emission Factors (AP-42)" must be used for the
                    conformity analysis unless more accurate emission data
                    are available, such as actual stack test data from
                    stationary sources which are part of the conformity
                    analysis.
          (c)  The air quality modeling analyses required under this
               subpart must be based on the applicable air quality models,
               data bases, and other requirements specified in the most
               recent version of the "Guideline on Air Quality Models
               (Revised)" (1986), including supplements (EPA publication
               no. 450/2-78-027R),  unless:
               (1)  The guideline techniques are inappropriate, in which
                    case the model may be modified or another model
                    substituted on a case-by-case basis or, where
                    appropriate, on a generic basis for a specific Federal
                    agency program; and
               (2)  Written approval of the EPA Regional Administrator is
                    obtained for any modification or substitution.
          (d)  The analyses required under this subpart, except section
               93.158, paragraph (a)(1), must be based on the total of
               direct and indirect emissions from the action and must
               reflect emission scenarios that are expected to occur under
               each of the following cases:
               (1)  The Act mandated attainment year or, if applicable, the
                    farthest year for which emissions are projected in the
                    maintenance plan;
               (2)  The year during which the total of direct and indirect
                    emissions from the action is expected to be the
                    greatest on an annual basis; and
               (3)  Any year for which the applicable SIP specifies an
                    emissions budget.

          93.160   Mitigation of air quality impacts.

          (a)  Any measures that are intended to mitigate air quality
               impacts must be identified and the process for
               implementation and enforcement of such measures must be
               described, including an implementation schedule containing
               explicit timelines for implementation.
          (b)  Prior to determining that a Federal action is in conformity,
               the Federal agency making the conformity determination must
               obtain written commitments from the appropriate persons or
               agencies to implement any mitigation measures which are
               identified as conditions for making conformity
               determinations.
          (c)  Persons or agencies voluntarily committing to mitigation
               measures to facilitate positive conformity determinations
               must comply with the obligations of such commitments.
          (d)  In instances where the Federal agency is licensing,
               permitting or otherwise approving the action of another
               governmental or private entity, approval by the Federal
               agency must be conditioned on the other entity meeting the
               mitigation measures set forth in the conformity
               determination.
          (e)  When necessary because of changed circumstances, mitigation
               measures may be modified so long as the new mitigation
               measures continue to support the conformity determination.
               Any proposed change in the mitigation measures is subject to
               the reporting requirements of section 93.156 and the public
               participation requirements of section 93.157.
          (f)  The implementation plan revision required in section 93.151
               of this subpart shall provide that written commitments to
               mitigation measures must be obtained prior to a positive
               conformity determination and that such commitments must be
               fulfilled.
          (g)  After a State revises its SIP to adopt its general
               conformity rules and EPA approves that SIP revision, any
               agreements, including mitigation measures, necessary for a
               conformity determination will be both State and federally
               enforceable.  Enforceability through the applicable SIP will
               apply to all persons who agree to mitigate direct and
               indirect emissions associated with a Federal action for a
               conformity determination.