UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105

September 21, 2016

Memorandum

To: Docket for the Approval and Promulgation of Implementation Plans; State of California; 

Coachella Valley; Attainment Plan for 1997 8-Hour Ozone Standard (Docket Number: 

EPA-R09-OAR-2016-0244)

From: Tom Kelly, Air Planning Office, EPA Region 9

RE: Motor Vehicle Emissions Budget Adequacy Documentation for Coachella Valley 1997 8-

Hour Ozone Standard State Implementation Plan

This memorandum documents the adequacy of the motor vehicle emissions budgets in the Staff Report, 

Proposed Updates to the 1997 8-Hour Ozone Standard, State Implementation Plans; Coachella Valley 

and Western Mojave Desert (CARB, Release Date: September 22, 2014). Additionally, a table of 

emissions budgets for the Coachella Valley is also included. 
 

Evaluation of the Motor Vehicle Emissions Budget Adequacy 

Adequacy Review Criteria 

(40 CFR part 93)

Criterion 

Satisfied?

Reference in SIP Document/Comments

Sec. 

93.118(e)(4)(i)

The plan was endorsed by 

the Governor (or designee) 

and was subject to a public 

hearing. 

Yes

The California Air Resources Board (CARB) conducted a public hearing on 

October 24, 2014, as noted in many documents including the transcript of the 

Board’s October 24, 2014, hearing. 

CARB notified the public of the hearing and the opportunity to provide public 

comment, either in person at the meeting, in writing at the meeting, or in 

writing prior to the meeting. 

The plan was submitted in a letter signed by Richard Corey, the Executive 

Officer of CARB and dated November 6, 2014.

Sec. 

93.118(e)(4)(ii)

The plan was developed 

through consultation with 

federal, state and local 

agencies; full 

implementation plan 

documentation was provided 

and EPA’s stated concerns, if 

any, were addressed.

Yes

Members of the Transportation Conformity Working Group of the South 

California Association of Governments (EPA, SCAQMD, CARB, South 

Coast Association of Governments (SCAG), Federal Highway 

Administration, Caltrans and many others) discussed the development and 

release of CARB’s 2014 SIP Update in August and September 2014 

meetings/conference calls. CARB also further coordinated with SCAG on 

motor vehicle emissions budgets and the (off-model) adjustments. 

CARB provided public notice of their implementation plan on September 22, 

2014, posted the implementation plan at 

https://www.arb.ca.gov/planning/sip/planarea/antvllysip.htm (see 2014 

Updates to the 1997 8-Hour Ozone Standard SIPs: Coachella Valley and 

Western Mojave Desert 8-Hour Ozone Nonattainment Areas) and provided 

access to the implementation plan in a link to the meeting agenda (see 

https://www.arb.ca.gov/board/ma/2014/ma102314.pdf). 
 

Sec. 

93.118(e)(4)(iii)

The motor vehicle emissions

budgets are clearly identified 

and precisely quantified. 

Yes

The motor vehicle emissions budgets for 2017 and 2018 are clearly identified 

and precisely quantified in Appendix E (Table D-1) of the 2014 SIP Update. 

These budgets reflect control measures that were already adopted by 

September 2012, as noted in the emissions inventory of Appendix A. The 

budgets were quantified with California’s approved (78 FR 14533, March 16, 

2013) emissions factor – 2011 model (or EMFAC2011), with one off-model 

adjustment for California’s Advanced Clean Car program, which has been 

incorporated into the California SIP (81 FR 39424, June 18, 2016).

Sec. 

93.118(e)(4)(iv)

The motor vehicle emissions 

budgets, when considered 

together with all other 

emission sources, are

consistent with applicable 

requirements for reasonable 

further progress and 

attainment.

Yes

EPA has preliminarily concluded that the budgets for the years 2017 and

2018, when considered together with all other emission sources and controls, 

are consistent with the requirement to demonstrate RFP for the 1997 8-hour 

ozone standard. This finding is based on a thorough review of the revised 

RFP demonstrations in Appendix C (Table C-1) of the 2014 SIP Update. This 

document supports the proposed approval of the RFP demonstration. 

EPA has preliminarily concluded that the budgets for the year 2018, when 

considered together with all other emission sources and controls, are 

consistent with the requirement to demonstrate expeditious attainment of the 

1997 8-hour ozone standard. This finding is based on review of the updated 

attainment demonstration in Appendix B of the 2014 SIP Update. EPA’s

proposed rulemaking for the Coachella Valley also proposes to approve 

attainment of the 1997 ozone standard, as discussed in Section IV.C of EPA’s 

proposed rulemaking.

Sec. 

93.118(e)(4)(v)

The plan shows a clear 

relationship among the 

emissions budgets, the 

control measures and the 

total emissions inventory.

Yes

The emission inventories for all point, area, and mobile sources are contained 

in Appendix A of the 2014 SIP Update. The control strategy relied upon for 

the SIP-based budgets is set out in the 2014 SIP Update. It consists of the 

existing rules submitted by SCAQMD by September 2012, as noted on page 

A-1 of the SIP Update, and CARB rules listed in Appendix E. The sole offmodel adjustment to the Emissions Factor 2011 (or EMFAC2011) model was 

for CARB’s Advanced Clean Car program, which was incorporated into the 

SIP (81 FR 39424, June 16, 2016). 
 

Sec. 

93.118(e)(4)(vi)

Revisions to previously 

submitted control strategy 

implementation or 

maintenance plans explain 

and document any changes to 

any previous submitted 

budgets and control 

measures, impacts on point 

and area source emissions,

any changes to established 

safety margins, and reasons 

for the changes (including 

the basis for any changes 

related to emission factors or 

estimates of vehicle miles 

traveled).

Yes

The previous submittal of the control strategy for the 1997 8-hour ozone 

standard was the South Coast 2007 Air Quality Management Plan.

a The motor 

vehicle emissions budgets were submitted separately in the 2008 Early 

Progress Plan,

b which was approved on May 7, 2008 (73 FR 25694). The 

early progress plan was submitted when EPA was changing its requirements 

for Reasonable Further Progress, therefore, it was intended to show “some 

progress toward attainment,” (see the Background on page 1 of the Early 

Progress Plan) but did not provide emissions budgets beyond 2012 (see the 

Coachella Transportation Conformity Budget on page 8 of the Early Progress 

Plan).

The motor vehicle emission inventories in the Early Progress Plan are based 

on an earlier emissions model, EMFAC2007, and motor vehicle emission 

inventories in the South Coast 2007 AQMP. The 2014 SIP Update was 

modeled with EMFAC2011. The Federal Register notice for the approval of 

EMFAC2011 (78 FR 14533, March 16, 2013) details the basis for the 

emission factor changes from the earlier EMFAC2007 model. The 2014 SIP 

Update also includes an updated emissions inventory from the 2007 AQMP. 

Appendix D lists State of California rules reducing emissions from motor 

vehicles. Another difference is that the 2014 SIP Update includes a 1 ton per 

day safety margin, and the 2008 Early Progress Plan did not. 

The net result of the changes between the 2012 budgets in the 2008 Early 

Progress Plan and the 2014, 2017 and 2018 budgets in the 2014 SIP Update is 

a 4 ton per day reduction of volatile (or reactive) organic compounds (7 tpd in 

2012 to 4 tpd in 2018) and 14 tons per day of NOx (26 tpd in 2012 to 12 tpd 

in 2018).

Sec. 

93.118(e)(5)

EPA has reviewed the State’s 

compilation of public 

comments and response to 

comments that are required 

to be submitted with any 

implementation plan.

Yes

The public comments begin on page 2 of the transcript for the California Air 

Resources Board meeting on October 24, 2014. No members of the public 

commented on the plan. One board member thanked the Board staff and 

proposed Board Resolution 14-29, which was unanimously supported by all 

Board members. No further public comments are noted in the transcript. 

a

“Final 2007 Air Quality Management Plan,” South Coast Air Quality Management District, June 2007. 

b

“Early Progress Plans Demonstrating Progress Toward Attaining the 8-hour National Air Quality Standard for Ozone and Setting Transportation 

Conformity Budgets for Ventura County, Antelope Valley - Western Mojave Desert, Coachella Valley, Eastern Kern County, and Imperial 
 

County” (revised), CARB (February 27, 2008).

Coachella Valley Motor Vehicle Emissions Budgets in the 2014 SIP Update (tpd, average 

summer weekday)a 

NOx VOC 

2014 2017 2018 2014 2017 2018 

On-Road Inventory 14.79 11.39 10.74 3.72 3.07 2.93

Safety Margin 1 1 1 1 1 1

MVEBsb 16 13 12 5 5 4

a Source: Table D-1, 2014 SIP Update.

b Rounded up to the nearest ton.