UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document 

for

EPA’s Rulemaking

for the

California State Implementation Plan

El Dorado Air Quality Management District

Ozone Emergency Episode Plan

Prepared by: Vanessa Graham

Reviewed by: Andrew Steckel

May 2016
1

RULE IDENTIFICATION -

Agency EL Dorado County Air Quality Management District (EDCAQMD)

SIP Approved

Plan

None

Subject of this 

TSD

Ozone Emergency Episode Plan

Adopted – January 12, 2016

Submitted – April 6, 2016

Completeness 

Finding

Determination of Completeness letter: April 21, 2016

BACKGROUND – Section 110(a) of Clean Air Act (CAA) requires each state to develop 

and submit to the EPA a plan that provides for the implementation, maintenance, and 

enforcement of the national ambient air quality standards (NAAQS). Section 110(a)(1) 

also requires that each state make a new State Implementation Plan (SIP) submission 

within 3 years after the promulgation of a new or revised primary or secondary NAAQS, 

for approval into the existing SIP to assure that the SIP meets the applicable requirements 

for the new or revised NAAQS. This type of SIP submission is commonly referred to as 

an “infrastructure SIP”. 

To facilitate planning efforts, the state of California is divided into air quality control 

regions (AQCR). Each AQCR is assigned Priority I, II or III with respect to emergency 

episode classification, based on threshold levels specified in the Code of Federal 

Regulations (CFR) at 40 CFR Part 51, Subpart H. Priority I and II areas have specific 

emergency episode plan requirements designed to prevent ambient concentrations from 

reaching specified significant harm levels (SHL). Priority III areas have no emergency 

plan requirements. 

SUMMARY – AQCRs with ozone concentrations greater than 0.10 ppm must be 

classified Priority I. Review of EDCAQMD 2011-2014 air quality data revealed that 

EDCAQMD exceeded the 0.10 threshold on numerous occasions1and recorded high onehour ambient levels of 0.117 ppm.2 Therefore, EDCAQMD is considered a Priority I 

region and is required to prepare an ozone emergency episode plan.3 EDCAQMD’s Ozone 

Emergency Plan, adopted on January 12, 2016, and submitted on April 6, 2016, was 

developed to fulfill the Infrastructure SIP emergency episode requirements as outlined in 

40 CFR Part 51, Subpart H.

Each Priority I contingency plan must, at a minimum4: 

1. Specify two or more stages of episode criteria;

 

1 El Dorado County Ozone Emergency Episode Plan, September 2015; page 1 Table 1.

2 California Infrastructure SIP Emergency Episode Planning Technical Support Document, EPA, Region 9, 

September 2014, pages 8-9.

3 Ibid.

4 40 CFR part 51, subpart H (51.153).
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2. Provide for public announcement whenever any episode stage has been determined 

to exist;

3. Specify adequate emission control actions to be taken at each episode stage;

4. Provide for prompt acquisition of forecasts of atmospheric stagnation conditions 

and forecast updates as frequently as they are issued by the National Weather 

Service;

5. Provide for inspection of sources to ascertain compliance with applicable control 

action requirements;

6. Provide communication procedures for transmitting status reports and orders as to 

emission control action to be taken during an episode stage, including contact with 

public officials, major emission sources, public health, safety, and emergency 

agencies and news media.

EVALUATION AND ACTION – EPA previously approved an analogous contingency 

plan for Placer County.

5 The El Dorado County Ozone Emergency Plan was largely 

modelled after the April 15, 2015 Placer County Air Pollution Control District Ozone 

Emergency Episode Plan. The El Dorado plan was tailored to meet the specific ozone 

emissions generated within El Dorado County. Our evaluation of the El Dorado County

Ozone Emergency Episode Plan finds the plan to be sufficiently clear and enforceable 

consistent with the general SIP enforceability requirements of CAA Section 110(a)(2).

This plan is specifically intended to address CAA Section 110(a)(2)(G) requirements for 

an emergency episode plan or rule, which is summarized in the list of six items above and 

described in greater detail in 40 CFR part 51, subpart H (40 CFR 51.150 through 51.153). 

The six requirements above are fulfilled by requirements on pages seven thru eleven of the 

plan. There were no deficiencies found, and the addition of the Ozone Emergency Episode 

Plan strengthens the SIP. Nothing in the EDCAQMD plan, or EPA’s approval of this plan,

interferes with EPA’s independent federal authority in CAA Section 303.

EPA RECOMMENDED ACTIONS – EPA staff recommends full approval of the plan 

as adopted on January 12, 2016 and submitted on April 6, 2016. 

ADDITIONAL RECOMMENDATIONS FOR THE NEXT RULE REVISION – EPA 

staff have no additional recommendations.

REFERENCES

1. California Infrastructure SIP prepared by ARB; Report Release December 23, 

2013.

2. California Infrastructure SIP Emergency Episode Planning Technical Support 

Document September 2014; prepared by USEPA, Region 9.

3. 40 CFR Part 51, Subpart H - Prevention of Air Pollution Emergency Episodes.

4. USEPA Guidance on Infrastructure State Implementation Plan (SIP) Elements 

under Clean Air Act Sections 110(a)(1) and 110(a)(2), Stephen D. Page (EPA), 

September 13, 2013. 

 

5 80 FR 76230 January 7, 2016 
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5. Placer County Ozone Emergency Episode Plan (80 FR 76230, January 7, 2016)

6. 65 FR 53602, September 5, 2000 (EPA approval of SMAQMD Rule 701).