Thursday, 

July 8, 2010 

Part III 

Environmental 

Protection Agency 

40 CFR Part 52 

Revisions to the California State 

Implementation Plan, Imperial County Air 

Pollution Control District; Final Rule 


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39366 Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 

1Our proposed rule and proposal TSD also 

describe additional improvements that we 

recommend for future ICAPCD modifications of the 

rules. This final action is not based on those 

recommendations. As a result, we do not respond 

here to all comments we received on them. 

2Letter with enclosure from Laura Yoshii (EPA), 

to James Goldstene (ARB), Re: exceptional events 

requests regarding exceedances of the PM10 NAAQS 

in Imperial County, CA, December 22, 2009. 

3 40 CFR 50.1(j) and 50.14. 

4 Issues related to the Regulation VIII deficiencies, 

significant source categories and our decision not 

to concur with the State’s exceptional events 

requests are addressed further below in our 

responses to comments we received on the 

proposed rule. 

5As used here and in the proposal TSD, the term 

‘‘off-highway vehicle’’ or OHV includes all vehicles 

subject to the exemption in Rule 800 section E.6 for 

recreational use of public lands in Imperial County. 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2010–0120; FRL–9169–2] 

Revisions to the California State 

Implementation Plan, Imperial County 

Air Pollution Control District 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: EPA is finalizing a limited 

approval and limited disapproval of 

revisions to the Imperial County Air 

Pollution Control District (ICAPCD or 

the District) portion of the California 

State Implementation Plan (SIP) under 

the Clean Air Act as amended in 1990 

(CAA or the Act). This action was 

proposed in the Federal Register on 

February 23, 2010 and concerns local 

rules that regulate coarse particulate 

matter (PM10) emissions from sources of 

fugitive dust such as construction sites, 

unpaved roads, and disturbed soils in 

open and agricultural areas in Imperial 

County. 

DATES: Effective Date: This rule is 

effective on August 9, 2010. 

ADDRESSES: EPA has established docket 

number EPA–R09–OAR–2010–0120 for 

this action. The index to the docket is 

available electronically at http:// 

www.regulations.gov and in hard copy 

at EPA Region IX, 75 Hawthorne Street, 

San Francisco, California. While all 

documents in the docket are listed in 

the index, some information may be 

publicly available only at the hard copy 

location (e.g., copyrighted material), and 

some may not be publicly available in 

either location (e.g., CBI). To inspect the 

hard copy materials, please schedule an 

appointment during normal business 

hours with the contact listed in the FOR

FURTHER INFORMATION CONTACT section. 

FOR FURTHER INFORMATION CONTACT: 

Andrew Steckel, EPA Region IX, (415) 

947–4115, Steckel.andrew@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, ‘‘we,’’ ‘‘us’’ 

and ‘‘our’’ refer to EPA. 

Table of Contents 

I. Summary of Proposed Action 

II. Public Comments and EPA Responses 

III. EPA Action 

IV. Statutory and Executive Order Reviews 

I. Summary of Proposed Action 

On February 23, 2010 (75 FR 8008), 

EPA proposed a limited approval and 

limited disapproval of the following 

rules listed in Table 1, known 

collectively as Regulation VIII, that were 

adopted by ICAPCD and submitted by 

the California Air Resources Board 

(ARB) for incorporation into the 

California SIP for the Imperial County 

serious PM10 nonattainment area. 

TABLE 1 

Local agency Rule No. Rule title Adopted Submitted 

ICAPCD ....... 800 General Requirements for Control of Fine Particulate Matter ....................................... 11/08/05 06/16/06 

801 Construction & Earthmoving Activities ........................................................................... 11/08/05 06/16/06 

802 Bulk Materials ................................................................................................................ 11/08/05 06/16/06 

803 Carry Out & Track Out ................................................................................................... 11/08/05 06/16/06 

804 Open Areas .................................................................................................................... 11/08/05 06/16/06 

805 Paved & Unpaved Roads .............................................................................................. 11/08/05 06/16/06 

806 Conservation Management Practices ............................................................................ 11/08/05 06/16/06 

We proposed a limited approval 

because we determined that these rules 

improve the SIP and are largely 

consistent with the relevant CAA 

requirements. We simultaneously 

proposed a limited disapproval because 

some provisions of the rules conflict 

with the CAA section 110(a) 

requirement that SIP rules must be 

enforceable and the requirement in 

section 189(b)(1)(B) for implementation 

of best available control measures 

(BACM) in serious PM10 nonattainment 

areas such as Imperial County. We 

discuss these statutory requirements 

and the Regulation VIII deficiencies in 

detail in the proposed rule and in the 

Technical Support Document for that 

proposal (proposal TSD).1 In the 

proposed rule and proposal TSD we also 

discuss our determination of which 

fugitive dust source categories 

addressed by Regulation VIII are 

significant and consequently require 

BACM pursuant to EPA guidance. This 

determination was based in part on our 

2009 decision 2 to not concur with the 

State’s request pursuant to EPA’s 

exceptional events rule 3 (EER) to 

exclude certain exceedances of the PM10

National Ambient Air Quality Standard 

(NAAQS) in Imperial County from 

consideration in regulatory actions 

under the CAA.4

We summarize the Regulation VIII 

deficiencies addressed in our proposed 

rule below. These deficiencies concern 

Regulation VIII provisions relating to 

open areas, unpaved roads and 

agricultural lands. 

A. BACM-Related Deficiencies for Open 

Areas 

1. Recreational Off-Highway Vehicle 

Activity 

While recreational off-highway 

vehicle (OHV) 5 activity causes much of 

the PM10 emissions from open areas in 

Imperial County, Rule 804 regulates 

only a small portion of these emissions, 

including those from OHV activity on 

State lands on which the rule is not 

being implemented. The vast majority of 

the OHV emissions in Imperial County 

are addressed only by requirements in 

Rule 800 section F.5 for dust control 

plans (DCPs) for sources under the 

control of the Bureau of Land 

Management (BLM). While BLM is 

required to describe in the DCPs the 

dust control measures that it intends to 

implement, BLM is not required to 

implement any specific BACM-level 

controls for OHV use. Moreover, 

ICAPCD has not provided an analysis of 

BACM for OHV activity, including 


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6 75 FR 8008, 8010–8011 and our proposal TSD, 

section III.B.1. 

7On August 11, 2004, EPA reclassified Imperial 

County as serious nonattainment for PM10. 69 FR 

48835. Since 2008 has passed, BACM is now 

required to be implemented as expeditiously as 

practicable. Delaney v. EPA, 898 F.2d 687 (9th Cir. 

1990). 

8 75 FR 8008, 8011 and our proposal TSD, section 

III.B.3. 

9 75 FR 8008, 8011 and our proposal TSD, section 

III.B.4. 

10 75 FR 8008, 8011. 

11 75 FR 8008, 8011–8012 and our proposal TSD, 

section III.B.4. 

12 75 FR 8008, 8012 and our proposal TSD, 

section III.B.4. 

13 75 FR 8008, 8012. 

potential OHV activity in open areas 

and on unpaved roads and paths that 

are exempt from the specific 

requirements and measures in Rules 804 

and 805. The proposed rule and 

proposal TSD address how ICAPCD can 

correct these deficiencies.6

2. Definition of ‘‘Disturbed Surface’’ 

The term ‘‘disturbed surface area’’ is 

used in several Regulation VIII rules but 

is never defined. For example, Rule 804 

applies to a source category for which 

BACM is required and relies on the 

undefined term to describe rule 

applicability in Rule 804 section B. A 

definition of this term is necessary in 

order to ensure that these rules are 

enforceable at a BACM level. 

B. BACM-Related Deficiencies for 

Unpaved Roads 

1. Unpaved Non-Farm Roads 

While CAA section 189(b)(1)(B) 

requires ICAPCD to implement BACM 

by 2008 (i.e., four years after 

reclassification to serious),7 Rule 805 

section E.7 allows the County until 2015 

to stabilize heavily-travelled unpaved 

roads. This schedule is inconsistent 

with the statutory requirement and 

ICAPCD has not provided adequate 

evidence that this schedule is as 

expeditious as practicable, based upon 

economic feasibility or any other 

appropriate consideration. In addition, 

Rule 805 section E.7’s requirement to 

stabilize all non-exempt unpaved 

County roads is not adequately 

enforceable as currently structured 

because it is not clear that the County 

is required to implement (and not just 

submit) a stabilization plan; stabilize 

different unpaved roads each year; and 

maintain all stabilized roads. The 

proposed rule and proposal TSD 

address how ICAPCD can correct these 

deficiencies.8

2. Unpaved Farm Roads and Traffic 

Areas 

Rule 805 section D.2 exempts 

agricultural roads and traffic areas from 

the opacity and stabilization 

requirements applicable to nonagricultural operation sites. Farm roads 

and traffic areas are only required to 

implement a conservation management 

practice (CMP) from the menus for 

unpaved roads and traffic areas in Rule 

806 in contrast to analogous rules in 

other geographical areas. 

Rule 806 sections E.3 and E.4 list 

CMPs intended to control emissions 

from agricultural unpaved roads and 

traffic areas but these measures are 

broadly defined and there is no other 

mechanism in the rule to ensure 

specificity. The absence of sufficiently 

defined requirements makes it difficult 

for regulated parties to understand and 

comply with the requirements, and 

makes it difficult for ICAPCD or others 

to verify compliance and to enforce the 

requirements if necessary. The lack of 

specificity similarly renders it difficult 

to assess whether the measures 

constitute BACM level controls. The 

proposed rule and proposal TSD 

address how ICAPCD can correct these 

deficiencies.9

3. Border Patrol Roads 

Rule 800 section F.6.c exempts roads 

owned or operated by the U.S. Border 

Patrol (BP) from Rule 805 requirements 

that are ‘‘inconsistent with BP authority 

and/or mission.’’ It is not clear what this 

exemption is intended to address, or 

how it would be implemented and 

enforced in order to meet BACM 

requirements. The proposed rule 

addresses how ICAPCD can correct 

these deficiencies.10

C. BACM-Related Deficiencies for 

Agricultural Lands 

1. Tilling and Harvesting 

Rule 806 sections E.1 and E.2 list 

CMPs intended to control emissions 

from agricultural land preparation and 

cultivation (including tilling), and 

harvest activities, but these measures 

are broadly defined and there is no 

other mechanism in the rule to ensure 

specificity. The absence of sufficiently 

defined requirements makes it difficult 

for regulated parties to understand and 

comply with the requirements, and 

makes it difficult for ICAPCD or others 

to verify compliance and to enforce the 

requirements if necessary. The lack of 

specificity similarly renders it difficult 

to assess whether the measures 

constitute BACM level controls. 

In addition, Rule 806 section E 

requires one CMP from the ‘‘land 

preparation and cultivation’’ category 

and one CMP from the ‘‘harvesting’’ 

category, while rules in other 

geographic areas have more stringent 

requirements. 

The proposed rule and proposal TSD 

address how ICAPCD can correct these 

deficiencies.11

2. Windblown Dust 

Windblown dust from non-pasture 

agricultural lands is also a significant 

source of PM10 that requires BACM 

independent of agricultural tilling. The 

CMPs in Rule 806 section E, however, 

mainly control emissions by reducing 

the number of vehicle passes across 

fields, and sources are not required to 

select BACM level practices for 

controlling windblown dust from active 

or fallow agricultural fields. The 

proposed rule and proposal TSD 

address how ICAPCD can correct these 

deficiencies.12

D. Non-BACM Deficiency 

Rule 802 section D.1 allows the Air 

Pollution Control Officer (APCO) to set 

aside controls that might be used 

instead of water to stabilize surfaces of 

bulk materials. This discretion allows 

ICAPCD to approve alternatives to the 

applicable SIP without following the 

SIP revision process described in CAA 

section 110. Moreover, ICAPCD has not 

demonstrated why such discretion is 

needed for measures such as covering, 

enclosing or sheltering material piles. 

The proposed rule addresses how 

ICAPCD can correct these 

deficiencies.13

II. Public Comments and EPA 

Responses 

EPA’s proposed action provided a 30- 

day public comment period. During this 

period, we received nine unique 

comment letters from public agencies 

and broad-based organizations. 

• Brad Poiriez, Air Pollution Control 

Officer, Imperial County Air Pollution 

Control District, March 25, 2010 

(ICAPCD). 

• Daniel Steward, Acting Field 

Manager, United States Department of 

the Interior, Bureau of Land 

Management, El Centro Resource Area, 

March 24, 2010 (BLM). 

• Kathleen Dolinar, District 

Superintendent, Ocotillo Wells District, 

California State Parks, Off-Highway 

Motor Vehicle Recreation Division, by 

e-mail dated March 24, 2010 (OWD). 

• Gail Sevrens, Acting District 

Superintendent, Colorado Desert 

District, California State Parks, by e-mail 

dated March 25, 2010 (CDD). 

• David P. Hubbard, Gatzke Dillon & 

Balance LLP, on behalf of EcoLogic 


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14Comite Civico Del Valle, Inc., v. Jackson, No. 

09–cv–04095 PJH (N.D. Cal.). 

15E-mail from Andrew Steckel, EPA, to Kathleen 

Dolinar, California State Parks, March 29, 2010. 

16See 5 U.S.C. 553. 

Partners, Inc., March 25, 2010 

(EcoLogic). 

• Lisa T. Belenky, Senior Attorney, 

Center for Biological Diversity, March 

25, 2010, representing several listed 

parties (CBD). 

• Jose Luis Olmedo, Executive 

Director, Comite Civico Del Valle, Inc., 

March 25, 2010, submitted and joined 

by other parties (Comite). 

• Ayron Moiola, Executive Director, 

Coalition of Labor, Agriculture & 

Business, March 24, 2010 (COLAB). 

• Mark McBroom, President, Imperial 

County Farm Bureau, March 24, 2010 

(Farm Bureau). 

We also received over 100 comment 

letters from individuals and 

organizations associated with 

recreational OHV activities. We 

reference these comments below by 

their identification in the Federal docket 

management system (FDMS) found at 

regulations.gov. For example, the 

comment listed in FDMS as document 

number ‘‘EPA–R09–OAR–2010–0120– 

0219’’ is referenced below as ‘‘0219.’’ 

We summarize the comments and 

provide our responses below. In our 

responses we identify specific 

commenters in some cases but not in 

others, particularly where many 

commenters made similar points. 

A. General 

These overarching comments largely 

provide general support or opposition to 

our proposal. 

General #1: CBD and Comite support 

EPA’s proposal to find that the 

Regulation VIII submittal does not fully 

implement BACM level controls for all 

significant source categories in Imperial 

County, and support EPA’s 

nonconcurrence with associated 

exceptional event requests. They ask 

EPA to finalize the proposed limited 

disapproval of Regulation VIII and to 

require additional PM10 emissions 

restrictions. Many other commenters 

disagree with EPA’s proposed limited 

disapproval, especially with EPA’s 

identification of deficiencies for BACM 

requirements and EPA’s 

nonconcurrence with exceptional 

events. ICAPCD, for example, believes 

that EPA’s proposal is arbitrary and 

capricious, and that California has 

demonstrated that all required BACM 

are being implemented in Imperial 

County. 

Response: No response is necessary 

for the overarching statements of 

support or opposition. Responses are 

provided below to the specific 

comments that support these general 

statements. 

General #2: Several commenters 

believe that EPA’s proposal lacks 

adequate scientific support. One (0144), 

for example, states that passing 

sweeping air quality regulations in an 

area with unique terrain and climate 

with only generalities to prove the 

sources of pollution is unethical and 

appears anti-development, anti-OHV 

and anti-agriculture. 

Response: The scientific support for 

EPA’s action is documented in our 

proposal and the associated proposal 

TSD and discussed further in response 

to specific comments below. See, for 

example, response to comment EI #3 

below. The serious health impacts of 

exposure to elevated levels of PM10 are 

well known and well documented and 

need not be reiterated here. 

General #3: ICAPCD objects to EPA 

taking over four years to act on its 

submittals of Regulation VIII for 

approval and claims that EPA is only 

now raising basic issues that ICAPCD 

believes should have been resolved 

before rule adoption. For example, 

ICAPCD objects to EPA disapproving a 

definition that it claims is clear and 

understood by all affected parties. 

ICAPCD and others (e.g., COLAB) 

comment that EPA never raised this and 

other concerns despite ICAPCD’s 

extensive public process and 

communication with EPA before rule 

adoption. ICAPCD also cites EPA’s 

testimony before the District Board in 

which the Agency supported Regulation 

VIII as BACM. As a result, ICAPCD 

concludes that EPA’s proposal 

undermines ICAPCD’s ability to rely on 

EPA comments in the future. 

Response: EPA reviews and 

comments on many draft State and local 

agency rules during their development 

prior to submittal to EPA for formal 

approval. It is generally more efficient 

for all parties to identify and resolve 

issues early in the process, rather than 

after rules are adopted and submitted to 

EPA for inclusion into the SIP. EPA’s 

formal action on local rules, however, 

can only occur through notice and 

comment rulemaking after rules have 

been officially submitted to EPA by the 

State. If EPA determines during that 

process that a submittal does not fulfill 

relevant CAA requirements, we cannot 

approve the submittal. Given time and 

resource constraints, it is not always 

possible for the Agency to identify or 

analyze fully all issues before State or 

local rule adoption. Moreover, EPA 

must carefully consider all public 

comments submitted on proposed EPA 

actions on State and local rules. Such 

comments often identify issues and 

concerns that may not have arisen 

during the prior evaluation of drafts of 

a rule. We continue to believe, however, 

that communication between EPA and 

State and local agencies at the rule 

development stage is productive. 

General #4: OWD asks EPA to extend 

the comment period because it was 

informed of EPA’s proposal only nine 

days before the close of the comment 

period. Several commenters also state 

that EPA did not provide adequate 

notification time (0218.1 and 0098) or 

consultation with State Park personnel 

(0218.1 and OWD). 

Response: EPA denied OWD’s request 

to extend the comment period because 

EPA is under a court order 14 to finalize 

action by June 15, 2010, and needs time 

to analyze all comments submitted on 

the proposal.15 While more time and 

outreach before EPA action is always 

desirable, nothing in the comments 

suggests that EPA failed to follow 

relevant public notification 

requirements found in the 

Administrative Procedures Act.16 EPA 

notes that OWD did comment on the 

proposal and EPA has taken those 

comments into consideration in the 

final action. 

B. State Implementation Plan (SIP) 

These comments generally address 

broad SIP issues rather than specific 

Regulation VIII provisions. 

SIP #1: OWD believes the PM10

standard is nearly impossible to attain 

given Imperial’s climate, natural desert 

condition, the cost of inappropriate 

BACM, and other local conditions. In 

contrast, Comite asks EPA to find that 

California has failed to submit a PM10

plan as required by 72 FR 70222 

(December 11, 2007), and to consider 

imposing associated CAA section 179 

sanctions and a section 110(c) Federal 

implementation plan (FIP) in this area. 

Response: Our proposed action 

addresses the CAA section 189(b)(1)(B) 

requirement for BACM for certain PM10

sources in Imperial County. The 

submittal at issue, Regulation VIII, is but 

one portion of the complete SIP that 

ICAPCD must develop in order to meet 

additional CAA requirements. These 

comments address the separate and 

broader statutory obligations for the 

State to submit a PM10 plan that, among 

other things, demonstrates expeditious 

attainment of the PM10 NAAQS. Those 

other obligations are not the subject of 

this action. 

SIP #2: ICAPCD does not believe that 

any additional controls such as those 

that may need to be implemented if EPA 

partially disapproves Regulation VIII 


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17 ‘‘State Implementation Plans for Serious PM–10 

Nonattainment Areas, and Attainment Date Waivers 

for PM–10 Nonattainment Areas Generally; 

Addendum to the General Preamble for the 

Implementation of Title I of the Clean Air Act 

Amendments of 1990;’’ 59 FR 41998 (August 16, 

1994) (General Preamble Addendum). 

18Under the General Preamble Addendum, a 

source category ‘‘will be presumed to contribute 

significantly to a violation of the 24-hour NAAQS 

if its PM10 impact at the location of the expected 

violation would exceed 5 μg/m3.’’ This is also 

referred to as the de minimis level. Id. at 42011. 

19 75 FR 8008, 8010, and proposal TSD, pp. 5–7. 

20 General Preamble Addendum at 42010. 

21EPA’s Air Quality System Preliminary Design 

Value Report (May 18, 2010) shows 17 exceedances 

of the 24-hour PM10 NAAQS in Imperial County 

between 2007 and 2009. 

22 56 FR 56694 (November 6, 1991). 

23 69 FR 48792; Sierra Club v. United States 

Environmental Protection Agency, et al., 346 F.3d 

995 (9th Cir. 2003); cert. denied, 542 U.S. 919 

(2004). 

24See section II.D.1 below. 

25 75 FR 8008, 8010 and proposal TSD pp. 5–7. 

26 40 CFR part 50, appendix K. 

27EPA’s Air Quality System Preliminary Design 

Value Report (May 18, 2010). 

28Cathedral City Municipal Code, title 8, chapter 

8.54, Fugitive Dust Control; http://qcode.us/codes/ 

cathedralcity/. 

29 2009 PM10 SIP table 4.2 and 2005 BACM 

analysis table 4.2. 

will prevent PM10 exceedances during 

high winds or otherwise materially 

benefit air quality on days unaffected by 

high winds. ICAPCD further believes 

that such additional controls will waste 

limited resources that should be used in 

other ways to improve local air quality 

in the area. 

Response: CAA section 189(b)(1)(B) 

and EPA guidance 17 require that BACM 

be implemented for all significant 

source categories 18 in serious PM10

nonattainment areas such as Imperial 

County. As explained in our proposal,19

we determined that each of the 

subcategories under open areas, 

unpaved roads and agricultural lands 

below meet or exceed the 5 μg/m3 de 

minimis level in our guidance and are 

therefore significant source categories in 

Imperial County: 

Open areas: 

—Windblown Dust, Other Open Area. 

Unpaved roads: 

—Entrained Unpaved Road Dust, City/ 

County. 

—Entrained Unpaved Road Dust, Canal. 

—Windblown Dust, Unpaved City/ 

County Road. 

—Windblown Dust, Unpaved Canal 

Road. 

—Windblown Dust, Unpaved Farm 

Road. 

Agricultural lands: 

—Tilling. 

—Windblown Dust, Non-Pasture 

Agricultural Lands. 

As EPA stated in the guidance, the 

structural scheme throughout title I of 

the CAA, including its provisions for 

the PM10 NAAQS, requires the 

implementation of increasingly 

stringent control measures in areas with 

more serious pollution problems. EPA 

further stated ‘‘that the more serious the 

air quality problem, the more reasonable 

it is to require States to implement 

control measures of greater stringency 

despite the greater burdens such 

measures are likely to cause.’’ 20

Imperial County continues to violate the 

PM10 standard 21 and our proposed 

action identifies several components of 

the State’s Regulation VIII submittal 

relating to open areas, agricultural lands 

and unpaved roads that do not fulfill the 

CAA BACM requirement and the 

enforceability requirements of CAA 

section 110(a). 

We further address ICAPCD’s 

contention that additional Regulation 

VIII controls will not prevent PM10

exceedances during high winds in our 

response to comment EE #1 below. 

SIP #3: Many commenters emphasize 

the importance of OHV areas in Imperial 

County for recreation, and believe that 

enjoyment of the desert should not be 

restricted. Commenters note that many 

organizations help keep the desert 

clean, and one commenter (0175.1) 

believes such efforts would be reduced 

if OHV areas are closed. 

Response: Recreation, enjoyment of 

the desert and clean deserts are 

certainly desirable, whether for OHV 

use or otherwise. However, except as 

implicit in our response to comment 

OHV #5 below, they are not germane to 

the evaluation in our proposal and in 

this final rule of Regulation VIII and its 

compliance with the applicable CAA 

requirements. 

SIP #4: Two commenters (OWD and 

0218.1) question whether EPA’s 

proposal is based on statistically 

significant data since there were only 

three PM10 exceedances within a three 

year period. 

Response: ICAPCD’s obligation to 

implement BACM for Regulation VIII 

fugitive dust sources derives from the 

Imperial County’s designation as 

nonattainment and classification as 

serious. On November 15, 1990, the date 

of enactment of the 1990 Clean Air Act 

Amendments, Imperial County was 

designated nonattainment and classified 

as moderate.22 On August 11, 2004, EPA 

reclassified the area as serious in 

compliance with a mandate of the U.S. 

Court of Appeals for the Ninth Circuit.23

The reclassification, pursuant to CAA 

section 188(b)(2), was based on a 

finding that the area failed to attain the 

PM10 NAAQS by the statutory deadline 

of December 31, 1994. Once reclassified 

to serious, the area was required to 

comply with CAA section 189(b)(1)(B), 

which required that BACM be 

implemented for the area four years 

after its reclassification to serious. 

The three exceedances to which OWD 

refers occurred during 2006 and 2007. 

The State requested that these 

exceedances be excluded from use in 

regulatory actions pursuant to EPA’s 

EER.24 Because we did not concur with 

the State’s request, BACM is required to 

be implemented for certain windblown 

dust source categories, including open 

areas, for which such controls would 

not have been required if we had agreed 

with the State.25 See our responses to 

Exceptional Events comments below. 

We also note that California has 

chosen to sample PM10 in Imperial 

County only one out of every six days. 

As a result, by regulation, each 

monitored exceedance is estimated to 

represent approximately six 

exceedances rather than one.26 For 

example, in 2009, ICAPCD reported 

three monitored exceedances at the 

Ethel Street monitoring site, which are 

estimated to represent 18.3 exceedances. 

Exceedances were also monitored at 

Brawley, El Centro, Westmorland and 

Niland in 2009.27

SIP #5: Comite believes PM10 should 

be further controlled in Imperial County 

by adoption of local fugitive dust 

ordinances like those in Coachella’s 

Cathedral City, and by strengthening 

open burning regulations to be similar 

to those in the South Coast Air Quality 

Management District (SCAQMD) and 

the San Joaquin Valley Unified Air 

Pollution Control District (SJVUAPCD). 

Response: We assume the commenter 

refers to title 8, chapter 8.54 of 

Cathedral City’s municipal code which 

describes requirements for construction, 

unpaved roads and other local dust 

sources.28 These requirements are 

generally similar to the type of controls 

adopted by SCAQMD (e.g., Rule 403), 

SJVUAPCD (e.g., Regulation VIII) and 

ICAPCD (Regulation VIII). The 

commenter does not identify any 

specific Cathedral City controls that it 

believes are needed in ICAPCD 

Regulation VIII to constitute BACM. 

Except where identified in our proposal, 

we believe ICAPCD’s BACM analyses 

include adequate evaluation of 

analogous fugitive dust controls in other 

areas.29 It is possible that the 

commenter is recommending 

duplicative city ordinances that overlap 

County-wide Regulation VIII. While 

such redundancy could improve 

compliance, it is generally not necessary 


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30 General Preamble Addendum at 42013–42014. 

31E.g., OHV controls in Arizona Revised Statute 

§ 49–457.03 and Clark County Air Quality 

Regulations, section 90 (75 FR 8011, February 23, 

2010). 

32 General Preamble Addendum at 42010 and 

42012. 

33 In this respect, we do not agree with Comite 

that measures adopted in other areas are 

automatically transferable to Imperial County. 

34 ‘‘2009 Imperial County State Implementation 

Plan for Particulate Matter Less Than 10 Microns 

in Aerodynamic Diameter, Final,’’ adopted by 

ICAPCD Governing Board on August 11, 2009. 

(2009 PM10 SIP). 

35Proposal TSD, pp. 5–8. 

36 Id. at p. 8. 

37 Id. at pp. 5–8. 

38 2009 PM10 SIP, Chapter 3; Appendix III. 

39Proposal TSD, pp. 5–8 and 9–11. 

to meet CAA section 110(a) 

enforceability requirements. 

Finally, our proposed action only 

addresses the ICAPCD controls for 

certain PM10 source categories 

encompassed by Regulation VIII, and 

therefore does not address control of 

open burning or many other air 

pollution sources in Imperial County. 

See also responses to comments SIP #1 

and EI #1. 

SIP #6: Comite cites Vigil v. Leavitt, 

381 F.3d 826, 834 (9th Cir. 2004) and 

Hall v. EPA, 273 F.3d 1146 (9th Cir. 

2001), in commenting that measures in 

other areas can be considered BACM for 

Imperial County and are per se feasible. 

Comite further argues that what 

constitutes BACM can strengthen over 

time. In contrast, OWD does not believe 

that Imperial County should apply 

mitigation measures from other 

geographic areas (e.g., SJVUAPCD and 

Maricopa) that have different geologic 

and other local conditions. Similarly, 

COLAB believes that different cultural 

practices prevent ICAPCD from blindly 

implementing controls imposed in other 

areas, although the ICAPCD and 

SJVUAPCD CMP rules are very similar. 

Still another commenter (0119) claims 

that similar restrictions on construction, 

OHVs, farmers, etc., in Las Vegas and 

elsewhere have not been effective, and 

there is no need for such draconian and 

ineffective bureaucratic rules. 

Response: EPA believes that it is 

appropriate, when evaluating what 

constitutes BACM for a given source 

category, to consider controls that have 

been adopted and implemented in other 

geographical areas. EPA agrees that the 

facts and circumstances in a given area 

can affect what constitute BACM for 

that area, but that this determination 

must be based upon appropriate 

consideration of relevant information 

specific to that area. 

Comite does not explain how the 

cited cases support its position. 

Nonetheless, we agree that in evaluating 

BACM for Imperial County, ICAPCD 

should analyze analogous measures in 

other areas and that BACM may 

strengthen over time.30 Our proposal 

identifies several significant 

deficiencies in ICAPCD’s analysis to 

date.31 While BACM is determined on a 

case-by-case basis 32 and, as such, the 

analysis can include evaluation of local 

conditions that might make specific 

controls economically and/or 

technologically feasible in one area but 

not another,33 neither the 2009 PM10

SIP 34 nor the comment provides 

sufficient detail to adequately address 

the deficiencies identified in our 

proposal. 

OWD does not explain how Imperial 

County differs so markedly from the San 

Joaquin Valley and the Maricopa area 

that it would be inappropriate to 

consider BACM approved in those areas 

as part of the evaluation of controls for 

the same source categories in Imperial 

County. Similarly, COLAB does not 

elaborate on what ‘‘cultural practices’’ in 

Imperial County would justify 

disregarding approved BACM in the San 

Joaquin Valley and the Maricopa area as 

part of the evaluation of what controls 

would be appropriate for comparable 

source categories in Imperial County. 

C. Emissions Inventory (EI) 

EI #1: Many commenters oppose 

further OHV controls because they 

believe OHVs contribute little to 

Imperial County’s PM10 pollution 

problem compared to other sources. 

Commenters identify various sources 

they believe are more significant and/or 

should be further addressed instead, 

including fallow fields, fireplaces, feed 

lots, agricultural burning, pesticides, 

dirt roads, inefficient street lights, 

insufficient public transportation, 

insufficient speed limit enforcement, 

Interstate 8, the New River, the Salton 

Sea, Arizona to the east, San Diego to 

the west, Mexican roads, fires and 

factories to the south, rain, wind, 

erosion, dust storms and other natural 

occurrences. These commenters include 

OWD, 0096, 0097, 0150, 0139, 0152, 

0180, 0192, 0194 and 0219.1. 

Response: Our proposal explains that 

BACM is required for all significant 

PM10 source categories in Imperial 

County, that windblown dust from open 

areas is a significant PM10 source 

category, and that OHVs greatly increase 

emissions from open areas in Imperial 

County.35 Our proposal further explains 

that ICAPCD has not demonstrated 

implementation of BACM for open areas 

with respect to OHVs.36 These 

conclusions are based on inventory 

information prepared by ICAPCD and 

ARB and used during development of 

Regulation VIII and the 2009 PM10

SIP.37

The inventory in the 2009 PM10 SIP 

represents the most comprehensive 

information currently available on OHV 

emissions in Imperial County.38

ICAPCD’s analysis in the 2009 PM10 SIP 

concluded that windblown dust from 

open areas was not a significant source 

category, but this conclusion was 

premised upon many exceedences of the 

NAAQS being deemed to be the result 

of exceptional events. However, EPA’s 

own conclusion regarding those 

exceedences is that they were not 

caused by exceptional events and, as a 

result, we consider windblown dust 

from open areas to be a significant 

source category that is subject to the 

CAA’s BACM requirement. See response 

to comment SIP #4 and responses to 

Exceptional Events comments in section 

II.D below. Therefore ICAPCD has failed 

to meet the BACM requirement for 

windblown dust from open areas, in 

part because ICAPCD has not evaluated 

what controls might be appropriate for 

OHV activities in such areas. 

EPA’s action on the Regulation VIII 

submittal does not address or depend on 

whether additional controls may also be 

appropriate for the various other sources 

identified in the comments. 

EI #2: One commenter (0188) had 

driven past many farms in El Centro 

during tilling and observes that the dust 

was very minimal. Another (0201) 

thinks more attention should be paid to 

agriculture which the commenter 

believes is exempt from many of the 

environmental regulations. 

Response: See response to comment 

EI #1. Similar to emissions from open 

areas, EPA has concluded that 

emissions associated with tilling on and 

windblown dust from agricultural lands 

are significant source categories in 

Imperial County and, as such, ICAPCD 

needs to meet the BACM requirement 

for such sources.39

The commenter (0201) concerned 

about exemptions for agriculture did not 

specify which regulations exempt 

agriculture. As explained in our 

proposal, however, because certain 

agricultural-related activities constitute 

a significant source category for PM10 in 

Imperial County, ICAPCD is required to 

meet the CAA’s BACM requirements for 

such sources. Any ‘‘exemptions’’ for any 

such sources would need to be justified 

and explained in the context of meeting 

the BACM requirements. 

EI #3: Several commenters claim that 

EPA has not proved the impact of OHVs 


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40See, e.g., AP–42, Fifth Edition, Volume I, 

Chapter 13: Miscellaneous Sources, 13.2.2— 

Unpaved Roads, Final Section, EPA, November 

2006. This document provides EPA guidance on 

estimating emissions on unpaved roads and does 

not, for example, account for road terrain. http:// 

www.epa.gov/ttn/chief/ap42/ch13/index.html. 

41 2009 PM10 SIP, appendix III.B. 42 2009 PM10 SIP, p. 3–2. 43 In comparison to ICAPCD’s 22 tpd estimate. 

Proposal TSD, footnote 32. 44As discussed on pp. 5–8 of the proposal TSD, 

depending on the specific monitor, 2–3% of 

Imperial County’s annual inventory is calculated to 

result in a 5 μg/m3 contribution, which equates to 

about 6–8 tpd emissions. 

45 Id. 

46See, e.g., proposal TSD, p. 5. 

47 ‘‘Treatment of Data Influenced by Exceptional 

Events,’’ 72 FR 13560 (March 22, 2007) (EER). 

on PM10 levels sufficient to require 

additional OHV regulations. OWD 

notes, for example, that: (1) EPA did not 

analyze extreme terrain, thermal 

stability and other effects on winds in 

the desert; (2) most emissions from open 

lands come from undisturbed shrub/ 

grassland which are not anthropogenic 

sources; and (3) ICAPCD’s 2009 PM10

SIP, on which EPA relies, uses worstcase assumptions rather than actual soil 

condition information to estimate that 

OHVs represent less than 5% of the 

County’s total PM10 emissions (13.9 of 

282 tpd). OWD states that 99% of these 

total emissions relate to OHVs subject to 

Federal and State stewardship. 

Therefore OWD concludes that actual 

OHV emissions are small compared to 

worst-case estimates. OWD also 

questions EPA’s reference for the 

estimate of 22 tpd of windblown PM10

from OHVs. 

EcoLogic believes that EPA needs 

monitoring in the Ocotillo Wells State 

Vehicle Recreation Area (SVRA) and 

other areas to show how specific OHV 

activity affects sensitive receptors and 

for EPA to identify OHV activity as a 

major contributor to the County’s PM10

problem. Another commenter believes 

EPA lacks data tying PM to specific 

OHV activities (0218.1), and several 

commenters believe that any pollution 

from OHVs is virtually immeasurable. 

Several commenters believe additional 

inventory analysis is particularly 

important because OHV areas are far 

from population centers and monitors 

with PM10 exceedances. One commenter 

(0131) requests an unbiased third-party 

study of OHV impacts. CDD explains 

that PM10 emissions from several 

specific parks in Imperial County 

should be low, partly because OHV 

activity is prohibited. In contrast, CBD 

supports EPA’s claim that OHVs on 

BLM land cause considerable PM10 in 

Imperial County, and notes that BLM 

previously estimated PM10 impacts from 

OHV activities at the Aldodones Dunes 

alone as high as 11 tpd on holiday 

weekends. 

Response: It is extremely difficult to 

quantify and speciate accurately the 

myriad sources of PM10 emissions and 

PM10 precursor emissions spatially and 

temporally for purposes of modeling air 

pollution impacts and developing cost 

effective control programs. As a result, 

emission inventories are constantly 

being refined as more and better science 

and data become available. However, 

EPA, State and local air pollution 

agencies must make policy and 

regulatory decisions based on the best 

information available to comply with 

the CAA. As discussed in response to 

comment EI #1, the inventory and other 

information underlying our proposal 

regarding the emissions from OHV 

activity and the impacts of such activity 

represent the most comprehensive 

information currently available. 

Regarding specific concerns in this 

comment: 

(1) EPA’s conclusion that BACM is 

required for OHV activity relies on 

emissions inventory estimates that 

ICAPCD developed. If appropriate, 

ICAPCD could choose to refine those 

estimates to take into consideration 

factors such as terrain, thermal stability 

and other effects on winds in the desert, 

as well as distances between OHV areas 

and population centers and additional 

third party analysis. Such refinements 

are beyond the level of detail normally 

used in inventories required by CAA 

section 172(c)(3).40

(2) ICAPCD in its 2009 PM10 SIP 

quantifies the impact of soil type and 

land cover (e.g., shrub/grassland) and 

degree of OHV disturbance in OHV 

emission estimates relied on by our 

proposal.41

(3) ICAPCD used the best available 

information regarding soil types in open 

areas and determined that the remaining 

uncertainty does not affect the results of 

the technical analyses.42

(4) Even OWD’s 13.9 tpd OHV 

emission estimate, which we believe is 

too low,43 exceeds the presumptive 5 

μg/m3 de minimis level for source 

categories requiring BACM.44

(5) The reference for 22 tpd of 

windblown OHV emissions is 

accurately explained in our proposal.45

The comment that monitoring is 

necessary in the Ocotillo Wells SVRA 

and other areas before EPA should 

require controls for OHV activities is 

incorrect. As stated previously, under 

CAA section 189(b) and EPA guidance, 

BACM is required for all significant 

source categories in the nonattainment 

area, including windblown dust in open 

areas caused by OHV activity.46 Thus 

monitoring, which could provide 

valuable information, is nevertheless 

not necessary to determine which 

source categories require BACM. 

D. Exceptional Events (EE) 

1. Background 

On March 22, 2007, EPA adopted a 

final rule to govern the review and 

handling of certain air quality 

monitoring data for which the normal 

planning and regulatory processes are 

not appropriate.47 Under the rule, EPA 

may exclude data from use in 

determinations of NAAQS exceedances 

and violations if a State demonstrates 

that an ‘‘exceptional event’’ caused the 

exceedances. Before EPA can exclude 

data from these regulatory 

determinations, the State must flag the 

data in EPA’s Air Quality System 

database and, after notice and 

opportunity for public comment, submit 

a demonstration to EPA to justify the 

exclusion. After considering the weight 

of evidence provided in the 

demonstration, EPA decides whether or 

not to concur with each flag. 

On May 21, 2009, ARB submitted 

demonstrations for ‘‘high wind’’ events 

that allegedly caused ten exceedances of 

the 24-hour PM10 standard at various 

monitors in Imperial County in 2006 

and 2007. The demonstrations consisted 

of the following support documents 

(listed in Table 2) prepared by ARB, 

ICAPCD, and ICAPCD’s contractor, 

ENVIRON: 

TABLE 2 

Description Document date Abbreviated title 

Natural Event Documentation: Calexico and Westmorland, California—September 2, 

2006.

January 30, 2009 ................... September NED.48

Natural Event Documentation: Brawley and Westmorland, California—April 12, 2007 

[enclosed with June 13, 2008 letter to Sean Hogan].

April 15, 2008 ......................... Original April NED. 


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48We refer to the natural event documentation in 

these five documents, collectively, as the NEDs. 

49See footnote 2. We refer to our December 22, 

2009 letter and the enclosure hereafter as ‘‘2009 EE 

decision.’’ 

50Letter from Brad Poiriez (ICAPCD) to Jared 

Blumenfeld (EPA), March 3, 2010 with Attachment 

A and Appendix A1. 

51See 75 FR 8010 and the proposal TSD, pp. 

5–7. 

52We refer to ICAPCD’s March 10, 2010 letter 

with its Attachment A and Appendix A1, 

collectively, throughout our responses to the 

exceptional events comments in section II.D as 

‘‘Attachment.’’ 

53 ‘‘BACM is the maximum degree of emissions 

reduction of PM10 and PM–10 precursors from a 

source * * * which is determined on a case-by-case 

basis, taking into account energy, environmental, 

and economic impacts and other costs, to be 

achievable for such source through application of 

production processes and available methods, 

systems, and techniques for control of each such 

pollutant.’’ General Preamble Addendum at 42010. 

54Merriam-Webster’s Ninth New Collegiate 

Dictionary. 

55Similarly, EPA explained in the preamble to 

the EER that analysis of exceptional events includes 

consideration of whether anthropogenic activities 

have been controlled to the extent possible through 

use of all reasonably available reasonable and 

appropriate measures. 72 FR 13560, 13566, footnote 

11. 

56E.g., September NED, p. 9. 

57 2009 EE decision, section 4.2. 

58 General Preamble Addendum at 42008. 

TABLE 2—Continued 

Description Document date Abbreviated title 

Natural Event Documentation: Brawley, Calexico, El Centro, Niland, and Westmorland, 

California—June 5, 2007, Imperial County Air Pollution Control District [enclosed with 

June 13, 2008 letter to Sean Hogan].

April 15, 2008 ......................... Original June NED. 

Natural Event Documentation: Brawley and Westmorland, California—April 12, 2007 

[addendum to June 13, 2008 submittal].

March 12, 2009 ...................... April NED. 

Natural Event Documentation: Imperial County, California—June 5, 2007 [addendum to 

June 13, 2008 submittal].

March 12, 2009 ...................... June NED. 

As stated above in section I, on 

December 22, 2009, EPA denied ARB’s 

request to exclude all of the 

exceedances as exceptional events. The 

basis for our decision is specified in an 

enclosure which accompanied the 

December 22, 2009 letter.49 By letter, 

including Attachment A and Appendix 

A1, dated March 3, 2010, ICAPCD asked 

EPA to reconsider this decision.50

Our proposal on Regulation VIII 

explained that our 2009 EE decision led 

to an adjustment of ICAPCD’s 

significant source analysis which in 

turn led us to modify the list of 

significant sources for which BACM 

must be implemented in Imperial 

County under CAA section 

189(b)(1)(B).51 As a result, our 2009 EE 

decision was the subject of public 

comments on our proposed action. 

ICAPCD resubmitted its March 3, 2010 

letter, including Attachment A and 

Appendix A1, regarding our 2009 EE 

decision as Appendix C to its March 25, 

2010 comment letter on our Regulation 

VIII proposed action.52 EPA also 

received comments pertaining to our 

exceptional events decision from 

Comite and CBD. A summary of these 

comments and our responses follow. 

2. Events Not Reasonably Controllable 

or Preventable 

EE #1: ICAPCD (Attachment) 

disagrees with EPA’s interpretation of 

the requirement in the EER at 40 CFR 

50.1(j) that in order for an event to meet 

the regulatory definition of exceptional 

event, such event must be ‘‘not 

reasonably controllable or preventable.’’ 

Specifically ICAPCD takes issue with 

EPA’s statement in our 2009 EE decision 

that this criterion inherently implies ‘‘a 

requirement that the State demonstrate 

that anthropogenic sources contributing 

to the exceedance caused by the event 

were reasonably well controlled.’’ 

ICAPCD believes that under the plain 

regulatory language it is irrelevant 

whether ‘‘reasonable and appropriate’’ 

controls are in place on the day of an 

otherwise qualifying event when it can 

be shown that such controls would not 

reduce emissions and impact at the 

monitor sufficiently to prevent the 

exceedance. ICAPCD believes that it is 

inconsistent with the intent of the CAA 

for EPA to refuse to concur with an 

exceptional event claim solely due to 

EPA’s dissatisfaction with the 

stringency of certain controls when such 

controls could not have prevented the 

exceedance. 

Response: ICAPCD mischaracterizes 

both the plain language and the 

regulatory intent of 40 CFR 50.1(j) by 

reading the words ‘‘reasonably 

controllable or’’ out of that section. The 

regulation clearly requires a showing 

that the event is not either reasonably 

controllable or preventable, not as 

ICAPCD would have it, that the event 

cannot be controlled to the extent that 

no exceedance would have occurred. 

Furthermore, ‘‘control’’ as generally used 

in the CAA and EPA guidance (e.g., 

RACT and BACM 53), and as defined in 

the dictionary means to regulate or to 

reduce the incidence or severity.54 Thus 

the meaning of the word ‘‘control’’ 

undeniably differs from the words 

‘‘eliminate’’ or ‘‘prevent.’’ Therefore, to 

meet the ‘‘not reasonably controllable or 

preventable’’ criterion in 40 CFR 50.1(j), 

states must demonstrate that reasonable 

controls were implemented to regulate 

or reduce emissions regardless of 

whether the controls would have 

prevented exceedances.55 Finally we 

note that the relevance of dust controls 

is inherent in the District’s own 

characterization of the ‘‘event’’ as the 

combination of wind and dust 

entrainment from anthropogenic and 

nonanthropogenic sources.56

As discussed in our 2009 EE decision, 

the State failed to demonstrate that 

reasonable controls were implemented 

for anthropogenic sources contributing 

to the exceedances, including 

recreational OHVs and fallow 

agricultural fields.57 Nor does ARB or 

ICAPCD provide convincing evidence in 

the NEDs or elsewhere to support the 

claim that controls on these sources 

could not have either prevented the 

exceedances or reduced emissions. 

EE #2: ICAPCD (Attachment) further 

argues that the consequence of EPA’s 

action would be to require control 

measures beyond the area’s practical 

abilities—a result the EER is specifically 

designed to avoid. ICAPCD claims that 

other specific provisions are in place to 

prevent such difficulties, and ICAPCD 

quotes from EPA guidance: ‘‘If emissions 

from anthropogenic sources are reduced 

to the point that it is no longer 

technologically or economically feasible 

to reduce those emissions further, and 

the area still cannot attain the NAAQS, 

the EPA may consider waiving the 

serious area attainment date and 

appropriate serious area 

requirements.’’ 58

Response: The provisions to which 

ICAPCD refers are contained in CAA 

section 188(f) which authorizes EPA to 

waive subpart 4 requirements applicable 

to serious PM10 nonattainment areas, 

including BACM, where EPA 

determines that anthropogenic sources 

of PM10 do not contribute significantly 

to the violation of the standard in the 

area. Under section 188(f), EPA may 


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59 Id. at 42004. 

60 75 FR 8008, 8010–8012 and proposal TSD, pp. 

7–11. 

61The 2009 PM10 SIP for Imperial County that is 

intended to address the 5% requirement in CAA 

section 189(d) was adopted by ICAPCD in August 

2009 but has not been submitted to EPA by ARB. 

The plan concludes that the area would have 

attained the PM10 standard by the end of 2008 but 

for transported emissions from Mexico and with the 

‘‘exclusion of PM10 measurements affected by highwind exceptional events.’’ As a result of the claimed 

exceptional events, with which we did not concur 

in our 2009 EE decision, the plan also concludes 

that ‘‘[t]he 5% yearly emission reductions 

requirement does not apply to future years.’’ 2009 

PM10 SIP, section 5.3. 

62 2009 EE decision, section 4.2. 

63See id., section 4.2.1. 

64 2009 EE decision, pp. 4 and 7; 72 FR 13560, 

13569. 

65See 57 FR 13498, 13540–13541 (April 16, 1992) 

and the General Preamble Addendum at 42010. 

66 2009 EE decision, section 4.2.2; 72 FR 70222. 

67We note that in EPA’s Natural Events Policy 

which applied prior to the EER, we stated that 

‘‘BACM must be implemented at contributing 

anthropogenic sources of dust in order for PM–10 

NAAQS exceedances to be treated as due to 

uncontrollable natural events under this policy.’’ 

This requirement applied to moderate areas which 

otherwise would not have been required to 

implement BACM at all as well as to serious areas. 

Thus, while the EER does not include such a 

mandate, it is entirely appropriate and consistent 

with the Agency’s past practice to consider a BACM 

level of control in assessing whether reasonable 

controls are in place. Memorandum from Mary D. 

Nichols, EPA, ‘‘Areas Affected by PM–10 Natural 

Events,’’ May 30, 1996, p. 5. 

68 2009 EE decision, pp. 9–10. 

69 40 CFR 50.14(c)(3). 

also waive a specific date for attainment 

of the PM10 standard if the 

Administrator determines that 

nonanthropogenic sources contribute 

significantly to a violation of the 

standard. 

In guidance, EPA has established the 

same test for determining what 

constitutes a significant contribution for 

section 188(f) as is used for determining 

the sources for which BACM must be 

implemented under CAA section 

189(b)(1)(B).59 The passage in the 

guidance, quoted in isolation by 

ICAPCD, is preceded by a lengthy 

discussion regarding the circumstances 

under which a serious area such as 

Imperial County could qualify for 

section 188(f) waivers. That discussion 

makes clear that before EPA will 

consider waiving a serious area 

attainment date and requirements for a 

serious area that failed to attain the 

standard by the serious area deadline, 

the State must demonstrate that BACMs 

for significant anthropogenic sources 

have been implemented and that the 

area cannot attain the NAAQS with the 

implementation of additional control 

measures to achieve at least 5% annual 

emission reductions pursuant to CAA 

section 189(d). As discussed above and 

in the proposal,60 ICAPCD has not 

shown that BACM has been 

implemented as required by CAA 

section 189(b)(1)(B) for all significant 

source categories in Imperial County.61

Thus it would be difficult to show that 

additional controls are ‘‘beyond the 

area’s practical abilities’’ or ‘‘no longer 

technologically or economically 

feasible’’ without a more thorough 

BACM analysis. 

EE #3: ICAPCD (Attachment) believes, 

citing the preamble to the EER, that the 

rule only requires reasonable controls 

for anthropogenic sources within the 

State. 

Response: While Imperial County air 

quality may be affected by emission 

sources from areas outside California, 

such as Arizona and Mexico, our 2009 

EE decision relies on the lack of 

demonstrated controls for 

anthropogenic sources within 

California. 

EE #4: ICAPCD (Attachment) believes 

that EPA has not specified criteria for 

defining de minimis anthropogenic 

sources in the EER context, explained 

how the EER justifies such criteria, or 

described feasible analyses to 

implement such criteria. 

Response: As noted above, our 2009 

EE decision stated that inherent in the 

‘‘not reasonably controllable or 

preventable’’ criterion of the definition 

of ‘‘exceptional event’’ in 40 CFR 50.1(j) 

‘‘is a requirement that the State 

demonstrate that anthropogenic sources 

contributing to the exceedance caused 

by the event were reasonably 

controlled.’’ We also suggested that this 

requirement be limited to ‘‘all non-de 

minimis anthropogenic sources.’’ 62 In 

this case, however, rather than further 

interpreting the EER, we relied on 

statements in the NEDs acknowledging 

anthropogenic contributions in order to 

determine which anthropogenic sources 

were contributing to the 2006 and 2007 

exceedances.63

EE #5: ICAPCD (Attachment) opposes 

the statement in EPA’s 2009 EE decision 

that ‘‘because implementation of BACM 

is required in serious PM10 areas such 

as Imperial County under section 189(b) 

of the CAA, it is appropriate to consider 

that level of control in evaluating 

whether reasonable controls are in place 

for purposes of the Exceptional Events 

Rule.’’ Specifically, ICAPCD argues that 

(1) such a standard would create a new 

standard for exceptional event showings 

that is inconsistent with the language 

and intent of the EER which entails only 

‘‘reasonable’’ and not ‘‘best’’ control of 

anthropogenic sources; (2) the purpose 

of the EER is to protect states from 

consequences of reclassification as a 

result of exceptional events; (3) by 

definition, exceptional events fall 

outside the normal planning process 

and their analysis should not depend on 

elements of the normal planning process 

including designation status; and (4) the 

meaning of ‘‘reasonable controls’’ for the 

EER should not vary by an area’s 

nonattainment status and should not be 

as stringent as BACM. 

Response: As stated in our 2009 EE 

decision and in the preamble to the 

EER, EPA addresses the EER criteria, 

including that the event must be ‘‘not 

reasonably controllable or preventable,’’ 

on a case-by-case basis considering the 

weight of available evidence.64 Thus it 

is appropriate to consider the totality of 

circumstances in Imperial County in 

determining what constitutes 

‘‘reasonable’’ controls. We note again 

that the County has been designated 

nonattainment and classified as 

moderate or serious since 1990. The 

area was reclassified to serious in 2004. 

In evaluating rules as RACM or 

BACM, EPA has long considered it 

appropriate to consider local conditions 

since what is technologically and 

economically feasible in one area may 

not be in another.65 Moreover, EPA’s 

2009 EE decision did not define 

reasonable control as BACM in all cases 

or suggest that the EER mandates such 

an outcome. Rather, we stated that 

‘‘[b]ecause implementation of BACM is 

required in serious PM10 nonattainment 

areas such as Imperial County under 

CAA section 189(b), it is appropriate to 

consider that level of control in 

evaluating whether reasonable controls 

are in place for purposes of the 

Exceptional Events Rule.’’ 66 67 While 

ICAPCD states that this is inappropriate 

reliance on the normal planning 

process, an area’s nonattainment 

designation and classification are 

inherently part of the local conditions 

that are appropriately factored into what 

controls are reasonable for purposes of 

the EER. We also noted that ARB had 

failed to demonstrate any meaningful 

analysis of BACM or any other level of 

control for either OHVs or fallow fields, 

despite apparent significant emissions 

and available controls imposed 

elsewhere.68

EE #6: ICAPCD (Attachment) 

comments that OHV emissions were 

quantified in the 2009 PM10 SIP at 

EPA’s request, but EPA ignored this 

information in its analysis of the 

exceptional event requests. 

Response: It is the responsibility of 

the State to submit demonstrations 

addressing the EER criteria 69 to support 

its exceptional event requests and it is 

generally not appropriate or feasible for 


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70E.g., June NED, p. 2. 

71E.g., 2009 EE decision, footnotes 12, 15 and 16. 

72 57 FR 18070, 18072 (April 28, 1992). 

73 2009 EE decision, pp. 8–9. 

74E.g., 22 tpd windblown and 1.34 tpd entrained 

emissions, 2009 EE decision, p. 9. 

75Particularly recent activity where there has not 

been time or conditions to repair surface crusts. 

76 2009 EE decision, section 4.2.3. 

77April and June NEDs, pp. 13–14, and 

September NED, p. 18. 

78April and June NEDs, p. 13. 

79 2009 EE decision, p. 9. 

80 ‘‘Draft Final Technical memorandum: 

Regulation VIII BACM Analysis,’’ October 2005 

(2005 BACM Analysis). 

81 2009 EE decision, p. 9. 

us to correct NED deficiencies by 

searching for additional information. 

Nonetheless, we did review the 2009 

PM10 SIP before preparing the 2009 EE 

decision and did not ignore ICAPCD’s 

efforts to quantify OHV emissions in the 

2009 PM10 SIP. In fact, the 2009 EE 

decision references these efforts which 

undermine the assumption in the 

NEDs 70 that windblown dust from 

desert areas is entirely from nonanthropogenic sources.71

EE #7: ICAPCD (Attachment) believes 

it is not clear whether OHV sources 

should be considered de minimis, what 

controls EPA expects for illegal OHV 

use, and why current regulations do not 

constitute reasonable controls. 

Response: As stated previously, the 

State must demonstrate implementation 

of reasonable controls in documentation 

supporting exceptional events requests. 

It is possible that ICAPCD/ARB may be 

able to demonstrate in support of future 

exceptional events requests that OHV 

sources are de minimis, that there are no 

reasonable controls for OHVs under 

certain circumstances (e.g., certain 

illegal uses), and/or that existing 

regulations constitute reasonable 

controls. The 2009 EE decision, 

however, explains that the NEDs did not 

provide meaningful analysis of any level 

of control for OHVs, and that such 

analysis should include as a starting 

point evaluation of EPA’s RACM 

guidance 72 and regulations adopted 

elsewhere under similar conditions.73

EE #8: ICAPCD (Attachment) 

comments that sand dunes are naturally 

fully disturbed and that the 2009 PM10

SIP conservatively projects that OHVs 

contribute only 0.9 tpd (10%) to the 

total windblown emissions from them. 

Other commenters similarly question 

EPA’s assumption that OHVs disturb 

desert crust. OWD, for example, notes 

that dune laminae are often mistaken for 

a crust but are broken by wildlife, foot 

traffic and high winds. 

Response: We agree that effective 

control of fugitive dust is more difficult 

for the sand dunes than for other parts 

of Imperial County with different soil 

types. As a result, the State may be able 

to demonstrate in support of future 

exceptional events requests, or for other 

CAA purposes such as section 

189(b)(1)(B) BACM, that dust control for 

dunes should be different from and/or 

less stringent than controls required for 

other areas with different soil types. 

However, the September NED failed to 

provide meaningful analysis of 

reasonable OHV controls for the sand 

dunes or any other areas. This comment 

has no bearing on the April and June 

NEDs because the sand dunes were not 

implicated by those events. 

EE #9: ICAPCD (Attachment) 

comments that OHV activity and related 

direct PM10 entrainment should have 

been negligible because of the high 

winds during the April 12 and June 5, 

2007 events and thunderstorms on 

September 2, 2006. OWD notes that two 

of the exceedance events occurred 

during the OHV off-season and the third 

occurred in April, when OHV use is also 

low. Similarly, BLM comments that 

OHV use is lowest when dust potential 

is highest (June through September). 

Response: Our 2009 EE decision 

appropriately relies on OHV emission 

information from the NEDs and the 2009 

PM10 SIP which estimate large 

windblown dust emissions and 

significantly smaller directly entrained 

emissions.74 Thus, even if no OHVs 

operate and entrain dust on any 

exceedance days, previous 75 OHV 

activity still contributes to PM10

emissions by disturbing surfaces that 

subsequently emit windblown dust. As 

a result, documentation supporting 

future Imperial County exceptional 

events requests for events with 

significant emissions from OHV areas 

should include analysis of reasonable 

controls for OHVs even if there is no 

OHV activity during the exceedances. 

EE #10: ICAPCD (Attachment) 

comments that Regulation VIII 

agricultural controls are well beyond the 

reasonableness level required in the 

EER. ICAPCD further states that it and 

ARB have discussed agricultural 

controls with EPA for many years, 

worked with EPA during development 

of the 2005 BACM analysis, closely 

modeled Rule 806 on SJVUAPCD Rule 

4550 which EPA approved in 2004, and 

received EPA testimony in 2005 that 

Regulation VIII, including Rule 806, 

fulfilled BACM. ICAPCD also points out 

that the emission inventory in the plan 

shows that agricultural lands are 

significantly less emissive than most of 

the non-populated areas in Imperial 

County. 

Response: Our 2009 EE decision 

explains that neither Regulation VIII nor 

any other programs require any level of 

emissions control of certain fallow 

fields in Imperial County.76 Though 

ICAPCD comments that emissions from 

agricultural fields are smaller than 

emissions from other sources in the 

County, the NEDs for the exceptional 

events requests do not identify any 

anthropogenic sources as being de 

minimis. Rather, there are summary 

explanations that anthropogenic sources 

are reasonably controlled through 

Regulation VIII and other local 

programs.77 The only anthropogenic 

source discussed in any detail is 

agriculture in the April and June NEDs. 

These NEDs rely on the Imperial 

Irrigation District’s (IID) fallowing 

program as the basis for claiming that 

reasonable measures were in place for 

fallow fields which are not subject to 

ICAPCD’s Conservation Management 

Practices (CMP) Rule 806.78 However, 

there were approximately 32,000 fallow 

acres in Imperial County in 2007 that 

were not subject to either Rule 806 or 

IID’s program which is more than the 

approximately 18,000 acres that were a 

part of IID’s program in 2007.79 As 

explained in our response to comment 

EE #5, we stated in our 2009 EE 

decision that it is appropriate to 

consider a BACM level of control in 

evaluating whether reasonable controls 

are in place for purposes of the EER in 

Imperial County. However, EPA found 

no meaningful analysis of BACM or any 

other level of control for fallow land 

outside of IID’s program referenced or 

provided in the NEDs. 

EE #11: ICAPCD (Attachment) 

comments that EPA’s 2009 EE decision 

fails to mention Rule 806 in the 

discussion of controls for agricultural 

lands. ICAPCD notes that fallowed land 

issues were included in the 2005 BACM 

analysis 80 and concludes that failure to 

address Rule 806 makes EPA’s 

conclusions regarding agricultural areas 

suspect. 

Response: EPA did consider and 

reference Rule 806 in our 2009 EE 

decision.81 Although the 2005 BACM 

analysis includes incidental references 

to fallow lands, neither it nor the NEDs 

attempts to quantify the fallow acreage 

in Imperial County. Nor has the State 

demonstrated how any existing 

windblown dust controls might 

constitute BACM for fallow fields 

outside of IID’s program. 

3. High/Unusual Wind Events 

EE #12: Comite agrees with EPA’s 

disapproval of ARB’s request to exclude 

the monitored exceedances as 


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Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 39375 

82NRDC v. EPA, 559 F.3d 561, 565 (DC Cir. 2009). 

83 2009 EE decision, pp. 19–20. 

84September NED, pp. 12–14. 

85September NED, p. 12, and Attachment G, 

‘‘179B(d) ‘But For’ Analyses—High-Wind Events 

from Mexico’’, excerpt from Technical Support 

Document: Exclusion of PM10 Measurements in 

Excess of the 24–Hour PM10 NAAQS for Imperial 

County from 2001 through 2003 Due to Natural 

Events and Emissions from Mexico, Volume I of II, 

ENVIRON International Corporation, November 

2004. 

86 2009 EE decision, pp. 11 and 15. 

87 Id. at p. 11. 

88 Id. at p. 12. 

exceptional events. In support of our 

disapproval the commenter makes 

several arguments: (1) That there is no 

statutory or regulatory authority which 

allows windblown dust from land that 

has been disturbed by human activity to 

be considered ‘‘natural;’’ (2) that while 

the final rule includes specific language 

regarding the treatment of 

anthropogenic emissions associated 

with fireworks and prescribed burns, it 

does not include special provisions for 

anthropogenic sources affected by the 

wind; (3) that the portion of the 

preamble which suggests dust from 

anthropogenic sources may be treated as 

natural events in certain circumstances 

was a drafting error and is legally null; 

(4) where the Act does allow for 

consideration of human activity, it is 

limited to activity that is unlikely to 

recur at a particular location and 

agriculture does not meet that 

definition; and (5) regardless of whether 

a high wind event is classified as 

‘‘natural’’ or ‘‘human activity,’’ such an 

event exists only where the wind is 

objectively a ‘‘high wind’’ and 

sufficiently high to cause a monitored 

violation even in light of the 

implementation of whatever measures 

are ‘‘necessary’’ to protect public health 

under CAA section 319(b)(3)(A)(iv). 

Response: Comite’s support for our 

decision not to concur with the State’s 

exceptional events claims is noted. We 

agree with Comite that the events in 

question are not due to human activity 

that is unlikely to recur and that the 

State failed to demonstrate that the 

events qualify as natural events. 

However our conclusions with respect 

to natural events are not based on all of 

the legal arguments proffered by the 

commenter. We also are not relying on 

that portion of the preamble that the 

commenter correctly points out is a 

legal nullity 82 and instead, where 

appropriate, we rely on and cite to other 

parts of the preamble regarding natural 

events and high winds that remain 

applicable. While EPA’s views of the 

statute and the EER differ from 

Comite’s, we need not address Comite’s 

arguments in detail because its intent 

was clearly to support the outcome we 

have reached regarding the exceptional 

events claims. 

EE #13: Comite cites additional 

support for nonconcurrence with the 

State’s 2007 exceptional events requests 

beyond what was relied upon by EPA, 

namely that wind speeds were not 

shown to be ‘‘exceptional’’ for the area 

or ‘‘unusual’’ since the State relied on 

flawed comparisons to average wind 

speeds. 

Response: For the 2006 events, the 

State did not assert that the winds were 

unusually high. For both sets of 2007 

events, the evidence provided by the 

State did lead EPA to conclude that 

winds were unusually high.83 However, 

EPA’s 2009 EE decision did not rely on 

the State’s conclusions about unusual 

winds for any of the exceedances and 

we note that this commenter does not 

disagree with EPA’s conclusions on the 

exceptional events, or with EPA’s 

proposed limited disapproval of 

Regulation VIII. 

4. Clear Causal Relationship 

EE #14: Comite agrees with EPA that 

the State did not demonstrate there was 

a clear causal relationship between the 

exceedances and the events that are 

claimed to have occurred, as required 

under the EER. With regard to the 2007 

exceedances, the commenter cites the 

lack of sufficiently detailed source 

attribution data. With regard to the 2006 

exceedances, the commenter concludes 

that the proximity and nature of the 

thunderstorms that occurred in 

northwest Mexico made them ‘‘unlikely’’ 

to be the cause of the winds at Calexico. 

This commenter also believes that the 

possibility of any winds associated with 

thunderstorm activity north of the 

County being the cause of the 

Westmorland exceedance is 

‘‘problematical at best.’’ 

Response: Comite’s agreement with 

EPA’s 2009 EE decision regarding the 

2006 and 2007 exceedances is noted. 

EE #15: ICAPCD (Attachment) objects 

to EPA’s analysis of a section of the ARB 

documentation that compares 

September 2, 2006 to other days with 

similar meteorological conditions in 

order to establish a causal relationship 

between the claimed high wind event 

and the Calexico exceedances on 

September 2, 2006. ICAPCD also rejects 

EPA’s concerns regarding the effect of 

emissions from OHVs and fallow fields 

on the September 2, 2006 Calexico 

exceedances. ICAPCD concludes that 

EPA’s lack of sound technical 

understanding regarding the 

meteorological evidence and OHV and 

agricultural emissions led EPA to 

erroneously reject the State’s finding of 

a ‘‘clear causal relationship’’ for the 

September 2, 2006 Calexico 

exceedances. 

Response: In its documentation 

supporting its exceptional events 

request, the State compared PM10

concentrations on September 2, 2006 to 

those on fifteen other days that had 

similar meteorology at Calexico.84 The 

PM10 concentrations on most of the days 

were low, but on August 18, 2002, 

August 19, 2003 and September 2, 2006 

the PM10 concentrations were high. The 

concentrations on these days in 2002 

and 2003 are described in attachments 

to the State’s Natural Events 

Documentation 85 as being due to 

transport from Mexico under high wind 

conditions, and these conditions are 

stated to be meteorologically different 

than the other days at locations other 

than Calexico itself. Thus winds at 

Calexico were similar for all sixteen 

days, but on these specific days the 

wind elsewhere and the Calexico 

concentrations are higher. The State 

considered this to be evidence of an 

association or causal relationship 

between high wind elsewhere and high 

Calexico concentrations. 

While we acknowledge that we 

misinterpreted the above portion of the 

State’s argument in our initial analysis, 

our ultimate conclusion remains 

unchanged. As we discussed in our 

2009 EE decision,86 the State’s argument 

is flawed because there were in fact no 

high wind measurements on September 

2, 2006; instead, the State merely 

assumed that wind speeds increased to 

the east. As a result, the association 

between the winds and concentrations 

that was seen for the events in 2002 and 

2003 may not reflect what occurred on 

September 2, 2006. Thus our original 

conclusion is still valid because the fact 

remains that ARB’s argument is founded 

on speculation. As we explained in our 

2009 EE decision,87 such speculation is 

not adequate to establish a clear causal 

relationship. 

Furthermore, as also discussed in our 

2009 EE decision,88 significantly lower 

PM10 measurements in neighboring 

Mexicali contradict ARB’s assertion that 

the September 2, 2006 Calexico 

exceedances were caused by windblown 

dust from a large-scale, regional event 

that originated to the south or southeast 

of Calexico. Such an event would have 

affected both Calexico and Mexicali. 

ICAPCD itself concedes that its 

explanation for the Calexico 

exceedances does not account for the 

difference in the PM10 concentrations 


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89 ICAPCD Attachment A, Appendix A–1. 

90 Id. 

91 2009 EE decision, p. 14. 

92September NED, p. 15. 

93 ‘‘Technical Support Document for EPA’s Notice 

of Final Rulemaking on Revisions to the California 

State Implementation Plan, Imperial County Air 

Pollution Control District Regulation VIII—Fugitive 

Dust Rules 800–806’’ EPA Region IX, June 2010 

(final TSD), Figure 1. 

94Similar land use maps were provided in Figure 

3 of both the April and June NEDs. 

95Final TSD, Figure 1. 

96 2009 EE decision, p. 16. 

97September NED, Tables 1 and 2, and Figure 19. 

98Final TSD, figure 2. 

99September NED, pp. 10–11. 

100As we did in our 2009 EE decision, pp. 15 and 

19. 

101EPA received comments on its proposed EER 

which stated that we should replace the term ‘‘high 

winds’’ with the term ‘‘wind-generated dust.’’ In 

response to those comments, EPA explained in the 

final EER that the Agency chose to retain the 

original language because it accurately connotes the 

type of natural event that should be excluded under 

this rule and it serves as an indicator concerning 

the level of wind that caused the exceedance. See 

72 FR 13560, 13566. 

measured at the Calexico and Mexicali 

stations.89

ICAPCD further offers what it 

characterizes as the only three possible 

explanations for the Calexico 

exceedances, and suggests that EPA 

should accept the long range transport 

argument because it is the most 

plausible one.90 To do so would be to 

make a decision based on a 

predetermined outcome rather than 

reliable scientific data that establish a 

clear causal relationship as required by 

the EER. 

ICAPCD’s next objection to our 

analysis of ARB’s exceptional event 

request with respect to the September 2, 

2006 Calexico exceedances is that EPA’s 

concern regarding OHV and agricultural 

emissions 91 is not relevant because 

there are no OHV or domestic 

agricultural lands south, southeast or 

south-southeast of the Calexico 

monitors. EPA disagrees. The September 

NED states that the ‘‘source of the PM10

that impacted the Calexico stations 

corresponds to lands east and southeast 

of the Mexicali stations * * *’’ 92 In fact, 

as shown in the TSD for this final 

action,93 there is agricultural land 

immediately east of Calexico.94 As also 

shown in the final TSD,95 the southern 

end of the Imperial Sand Dunes OHV 

area is also directly east of Calexico, 

though it is admittedly farther away. 

Thus consideration of these sources was 

not inappropriate. 

In summary, we are not persuaded by 

the above comments and we reject the 

allegation that we did not have a sound 

technical understanding of the claims 

ARB made as to the cause of the 

exceedances. We therefore reaffirm our 

conclusion that ARB not only failed to 

demonstrate that a high wind event 

occurred, but also that there was a clear 

causal relationship between the alleged 

event and the September 2, 2006 

exceedances at the Calexico monitoring 

stations. 

EE #16: ICAPCD (Attachment) states 

that EPA mischaracterized some 

evidence and inappropriately dismissed 

other evidence provided by the State 

regarding a causal relationship between 

the claimed high wind event and the 

Westmorland exceedance on September 

2, 2006, and that this led EPA to 

erroneously reject the State’s finding of 

a clear causal relationship. The 

comment has three parts, relating to 

alleged EPA mischaracterizations of the 

timing of high winds, direction of 

thunderstorm travel, and wind 

trajectories. 

Response: In response to this 

comment, we have again reviewed the 

wind data provided in the September 

NED and, as explained further below, 

we believe our original conclusion in 

our 2009 EE decision remains correct, 

i.e., that the data presented by ARB did 

not demonstrate a clear causal 

relationship between the claimed high 

wind event and the Westmorland 

exceedance on September 2, 2006. 

The first part of ICAPCD’s comment 

focuses on a statement made by EPA 

that the increased wind at Oasis toward 

Westmorland was simultaneous with 

the concentration spike that occurred at 

Westmorland during the 19th hour 

rather than an hour or two before, as 

would be necessary based on the 

distance between the two locations.96

We agree with the comment that the 

increased wind at Oasis did in fact 

occur the hour before the concentration 

spike. In addition, we stated that this 

wind was directed toward Westmorland 

when in fact it was directed toward the 

east-northeast. 

ARB presented the wind speed and 

direction data in a tabular format that is 

difficult to interpret.97 To more clearly 

articulate why we do not believe these 

data show a clear causal relationship 

between the event and the exceedance, 

we have presented the data in the final 

TSD in a visual form that is more 

readily understood.98 The arrows 

represent the wind directions at Indio, 

Oasis, Salton Sea West, and 

Westmorland during each of the four 

color-coded hours (e.g., all of the yellow 

arrows represent the wind direction 

during hour 17, etc.). The numbers 

above each arrow represent the wind 

speed for that hour, and the numbers 

below the Westmorland arrows 

represent the PM10 concentration. The 

data show that the PM10 concentration 

spike occurred during hour 19. 

ARB claimed that thunderstorm 

outflows on September 2, 2006 led to 

high wind locally to the northwest and 

northeast of Imperial County, and that 

dust generated there was carried to 

Westmorland. More specifically, ARB 

stated the following: 

Very high winds were observed at the 17th 

and 18th hours north of Imperial County, 

both to the west (in particular at the Oasis 

CIMIS station, see Table 1) and to the east 

(see measurements at the Blythe, Ripley, and 

Palo Verde stations, Table 1). These strong 

winds were of very short duration and of 

changing direction * * *, consistent with the 

collapse of one or several thunderstorm cells 

north of Imperial County * * *. Very sharp 

peaks in PM10 concentrations were also 

observed at the 19th hour at the Brawley and 

Westmorland stations (and to a lesser extent 

at the Niland station), and appear to be longrange effects of the same events (i.e. 

collapsing thunderstorm to the north of 

Imperial County) * * *. [A]n analysis of 

wind direction at select stations between the 

18th and 20th hours indicates that northwest 

winds (e.g. 6 p.m. at the SSW and Indio 

stations, 7 p.m. at Oasis and Indio, and 8 

p.m. at Indio) and east-northeast winds (e.g. 

7 p.m. at the Niland and SSE stations) likely 

carried air containing elevated PM10

concentrations from areas northwest and 

northeast of Imperial County stations toward 

the stations.(Emphasis added).99

ARB’s explanation first points to the 

‘‘very high’’ winds (of 23.2 mph) 

recorded at the Oasis station and the 

northwest winds at Salton Sea West 

during the 18th hour as factors that 

contributed to the exceedance. As a 

preliminary matter, we note 100 that no 

particular wind speed has been 

established as ‘‘high’’ for Imperial 

County. Further, winds with an average 

speed of 23.2 mph are not what we 

would consider ‘‘very high’’ in the 

generally accepted meaning of the term. 

With the exception of this value, the 

data in Figure 2 of our final TSD show 

that the winds in this area were not very 

elevated.101 We also note that the winds 

at Oasis during the 18th hour had a 

northerly component rather than a 

southerly one, and while it is true that 

the winds at Salton Sea West were 

blowing toward Westmorland at this 

time and that these winds could have 

contained some of the dust that may 

have been generated in the Oasis area, 

the winds at Westmorland were blowing 

in almost the opposite direction. It is 

thus unclear how much, if any, dust 

generated at Oasis during the 18th hour 

was actually transported to 

Westmorland. 

ARB also points to the 7 p.m. winds 

at Oasis (hour 19) as a contributing 

factor. While these winds were directed 


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102 2009 EE decision, p. 16. 

103 72 FR 13560, 13573. 

104September NED, p. 2. 

105See CAA section 319(b)(3)(A)(i). 

106 2009 EE decision, p. 17. 

107 2009 EE decision, p. 14. 

108See Figure 1 in the final TSD. 

toward Westmorland, the winds at 

Salton Sea West had a distinct westerly 

component so it is not clear that the 

winds at Oasis continued on this path 

past Salton Sea West. In addition, as for 

the previous hour, the winds at 

Westmorland were blowing counter to 

the wind at Oasis and it is again not 

clear that any dust generated north of 

Imperial County was transported to 

Westmorland during this hour as ARB 

claims. 

The State finally points to the 8 p.m. 

winds at Indio as a contributing factor. 

We find it unlikely that these winds 

made a significant contribution to the 

exceedance at Westmorland given that 

they were recorded after the 

concentration spike occurred and that 

the winds at Oasis, Salton Sea West, and 

Westmorland all had northerly 

components that ran counter to the 

winds at Indio. 

As stated in our 2009 EE decision,102

and as ARB stated in the paragraph 

quoted above, the winds northwest of 

Imperial County (particularly around 

the Oasis and Salton Sea West areas) 

were variable in speed and direction. 

This variability is inconsistent with 

ARB’s hypothesis that the winds 

remained at an elevated speed and along 

a straight line over the 45 mile distance 

between Oasis and Westmorland for an 

hour or more. Thus it is anything but 

clear that dust generated northwest of 

Imperial County caused the exceedance 

at Westmorland. As a result, EPA’s 

minor errors regarding the timing and 

direction of the winds at Oasis do not 

undermine the Agency’s conclusion that 

the contradictory evidence does not 

support a finding of a clear causal 

relationship. 

The second part of ICAPCD’s 

comment on the causal relationship 

regarding the Westmorland exceedance 

argues that the speed and direction of 

the increased winds (27.0 mph) 

recorded at the Palo Verde station 

during hour 17 are consistent with 

transport to Westmorland and that the 

uncertainty of the precise location of the 

thunderstorms in time is not relevant to 

a cause and effect analysis. The 

commenter further states that EPA does 

not appear to argue that the wind speed 

or direction is inconsistent with 

transport of dust from Palo Verde to 

Westmorland. 

While we agree with the commenter 

that the winds at Palo Verde (which is 

separated from Westmorland by a northsouth distance of about 24 miles) were 

directed toward Westmorland during 

the 17th hour, the winds at 

Westmorland were consistently from the 

south-southeast, southeast, and eastsoutheast directions beginning at the 6th 

hour and lasting until the end of the 

day. While it is remotely possible that 

the winds that occurred at Palo Verde 

during the 17th hour led to the transport 

of dust to Westmorland, the EER 

requires a demonstration of a clear 

causal relationship and the limited data 

available do not rise to that level. 

We also disagree with the commenter 

that the location of the thunderstorms 

over time is not relevant to a cause and 

effect analysis. The EER explicitly 

mentions the use of data that show the 

relationship in time between the event, 

transport of emissions, and recorded 

concentrations in exceptional event 

demonstrations.103 Furthermore, in this 

case, ARB’s basic premise is that 

‘‘thunderstorm activity caused strong 

outflow winds over areas in close 

proximity to Imperial County monitors 

* * * [which contributed] to the 

elevated PM10 concentrations that were 

recorded in Imperial County on that 

day.’’ 104 ARB could have attempted to 

provide more support for its case by, for 

example, considering whether historical 

radar data showed thunderstorms were 

at various locations around the time the 

high winds occurred. 

Given the level of uncertainty as to 

the cause of the concentration spike at 

Westmorland during the 19th hour and 

the statutory requirement that EPA’s 

exceptional events regulations be based 

on the principle that protection of 

public health is the highest priority,105

we are again led to the conclusion that 

the data before the Agency does not 

establish a clear causal relationship 

between the exceedance and the event 

that is claimed to have occurred. 

The third part of ICAPCD’s comment 

regarding causal relationship for the 

Westmorland exceedance criticizes 

EPA’s use of wind trajectories from the 

HYSPLIT model since it is expected to 

capture the underlying flow pattern but 

may not be able to capture the direction 

of short-lived high winds that could 

transport dust from the north to 

Westmorland. 

EPA acknowledges that the HYSPLIT 

model uses meteorological data with 

relatively coarse resolution, e.g., a 40 

km grid, and that there may be shortlived or local deviations from the 

overall wind flow. However, it remains 

true that the HYSPLIT back-trajectories 

are inconsistent with transport from 

northern stations since they show winds 

from the south.106 The HYSPLIT data 

simply add to the list of inconsistencies 

in the State’s explanation. In addition, 

ICAPCD’s suggestion that the high 

winds were ‘‘short-lived’’ is inconsistent 

with ARB’s hypothesis of straight line 

transport from the Oasis or Palo Verde 

stations for an hour or more over the 

45–55 mile distance to Westmorland. 

Thus EPA disagrees with this comment. 

EE #17: ICAPCD (Attachment) makes 

an additional two-part comment about 

the causal relationship claim for the 

September 2, 2006 exceedances at both 

the Calexico and Westmorland 

monitoring stations. In order to buttress 

its argument that these exceedances 

were not the result of recurring 

anthropogenic sources within Imperial 

Valley, ICAPCD first states that it is 

extremely unlikely that all monitors in 

the County would simultaneously have 

had unusually high PM10 concentrations 

if the causes were local to the monitors. 

The second part of the additional 

comment states that since there were no 

high winds throughout Imperial Valley 

on September 2, 2006, the cause of the 

exceedances could not have been 

unpaved roads or agricultural or OHV 

land within the Valley. 

Response: With respect to the first 

part of ICAPCD’s comment, EPA 

acknowledged the elevation of PM10 at 

all monitors, but did not take a position 

on whether the causes were local or 

regional.107 Rather, we concluded that a 

clear causal relationship had not been 

demonstrated since the regional sources 

alleged by ARB to be the cause were not 

identified. Related to this lack of 

identification of the contributing 

sources, EPA found that the State did 

not demonstrate that the event was not 

reasonably controllable or preventable 

as there was no attempt to analyze 

controls on the non-local sources. Thus 

this comment does not affect our 

decision to not concur with the State’s 

exceptional event claims. 

With respect to the second part of 

ICAPCD’s comment, as discussed above, 

the State argued that high winds 

associated with thunderstorm activity 

led to the generation of dust north of the 

County, which was then transported to 

the Westmorland monitor. Even though 

agricultural land and other 

anthropogenic sources do exist in areas 

north of the County including Oasis,108

where the State claimed winds were 

high, the State made no attempt to 

analyze controls on contributing sources 

outside the County in order to address 

the EER requirement that the event must 

be ‘‘not reasonably controllable or 

preventable.’’ Thus, this requirement 


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39378 Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 

109pp. 25–27. 

110See, e.g., 2009 EE decision, p. 7 and our 

responses to comments EE #s 1 and 4. See also 72 

FR 49046, 49051 (August 27, 2007) and 72 FR 

13560, 13566, footnote 11, explaining that the 

weight of evidence approach to our analysis may 

consider winds that produce emissions contributed 

to by anthropogenic activities that have been 

controlled to the extent possible through use of all 

reasonably available reasonable and appropriate 

measures. 

111 72 FR 13560, 13573. 

112 2009 EPA decision, pp 17–18. 

113September NED, p. 2. 

was not met even if the commenter’s 

arguments regarding transport were 

correct. With respect to the Calexico 

exceedances, the State speculated that 

high winds occurred east and southeast 

of Calexico based on extrapolation of a 

west to east trend of increasing wind 

speed. The same argument could have 

been used to conclude that there was 

high wind east of Calexico within 

Imperial County, including over 

agricultural and OHV lands. Therefore 

the commenter’s claim that there were 

no high winds throughout the Imperial 

County is not completely supported by 

the State’s own arguments that a high 

wind event occurred. 

5. Concentrations in Excess of Normal 

Historical Fluctuations 

EE #18: Comite cites additional 

support for nonconcurrence beyond 

what was relied upon by EPA. 

Specifically, the commenter states that 

numerous monitored exceedances 

comparable to those that Imperial 

County seeks to exclude from the data 

have been measured in the County from 

2003–2007. Therefore, the commenter 

claims, the concentrations are not ‘‘in 

excess of normal historical fluctuations’’ 

as required by the rule and are not 

exceptional events. 

Response: EPA’s conclusions about 

the requirement that the events be 

associated with measured 

concentrations in excess of normal 

historical fluctuations mainly relied on 

the concentrations’ rarity relative to past 

measurements. For example, the 

September NED states that the 167 μg/ 

m3 measurement at the Westmorland 

station was in the 98th percentile of all 

PM10 recordings at that station in the 

2001–2007 time period. As explained in 

our 2009 EE decision,109 we found 

similar evidence that the exceedances 

measured on the other days in question 

also exceeded normal historical 

fluctuations. However, we do agree with 

the commenter that the monitoring data 

for Imperial County continue to show 

violations of the 24-hour PM10 standard. 

We believe that improvements to the 

ICAPCD’s rules will lead to 

improvements in air quality and we 

note that this commenter does not 

disagree with EPA’s conclusions 

regarding the State’s exceptional events 

requests, or with EPA’s proposal to 

disapprove Regulation VIII. 

6. Level of Documentation Required for 

EER 

EE #19: ICAPCD (Attachment) takes 

issue with EPA’s suggestions that 

additional data and analysis would have 

helped establish causality for the 2006 

Westmorland and the 2007 events. 

Specifically, ICAPCD states: 

Although EPA suggests that higher levels 

of documentation for source attribution, 

thunderstorm activity, or investigation of 

other potential causes would be preferred, 

EPA does not suggest reasonable, technically 

implementable analyses to achieve these 

higher levels of documentation. We would 

question what technical analyses EPA 

suggests should be conducted. We would 

also question whether these analyses and the 

required level of data are achievable or 

realistic now or in the future for similar 

events in Imperial County and in other areas 

(particularly those surrounded by remote, 

non-populated, non-monitored source areas), 

and whether these analyses exceed the 

requirements for SIP planning itself. EPA has 

not (and, we believe, cannot) propose 

reasonable, technically achievable 

investigations and analyses superior to those 

produced by the District and ARB that would 

address EPA’s stated concerns. Thus, we find 

that both EPA’s conclusions on causality and 

EPA’s position on the level of analysis 

required to demonstrate causality are 

incorrect and inconsistent with the purpose 

of the EER * * *. Such a narrow application 

of the EER will preclude states from 

excluding from regulatory consideration 

exceptional PM data that are completely 

inappropriate for inclusion in the normal 

planning process. 

ICAPCD also includes a table on page 

A–8 which cites specific passages of 

EPA’s 2009 EE decision pertaining to 

source apportionment, satellite imagery, 

and consideration of other causes. 

Response: Regarding the need for 

better source apportionment data, it is 

important to identify contributing 

sources when evaluating exceptional 

event claims involving windblown dust 

because it must be demonstrated that 

anthropogenic sources contributing to 

the exceedances at issue were 

reasonably controlled.110 Better source 

identification is especially important in 

situations where we do not have 

confidence that all potential 

anthropogenic sources are reasonably 

controlled and where there are 

exceedances just above the NAAQS 

(such as the April 12, 2007 exceedance 

at Westmorland) which may have been 

preventable with additional controls. In 

addition, the inability to identify the 

source of the PM emissions associated 

with a wind event (i.e., the ‘‘cause’’ of 

the dust that led to the exceedance) 

hinders our ability to make affirmative 

findings that the ‘‘clear causal 

relationship’’ and ‘‘but for’’ provisions of 

the EER have been satisfied. A Countywide monthly average emission 

inventory such as the one used by ARB 

that omits some source types (e.g., 

OHVs) is insufficient for these purposes. 

While perhaps not required for all 

demonstrations, our suggestion for a 

wind field and a more highly resolved 

inventory are not unreasonable given 

ARB’s failure in the present case to 

demonstrate that reasonable controls 

were in place for contributing sources. 

Moreover, a more highly resolved 

inventory would provide better support 

for any future exceptional events claims 

involving Imperial County. Another 

method ARB could have potentially 

considered for identifying the source of 

the emissions and supporting its claim 

of a causal relationship is to collect and 

examine pollutant species-specific 

information. As discussed in the EER 

preamble,111 such information may be 

available through routine speciation, 

monitoring networks, or from selective 

laboratory analysis of archived 

particulate matter filters for the day 

thought to be impacted by an event. In 

this case, such an analysis might have 

helped ascertain how much of the PM10

that impacted certain monitors was from 

agricultural sources versus natural 

desert sources. 

Regarding ICAPCD’s objection to our 

statement that the satellite imagery 

provided was not frequent enough to 

compare the images with the timing of 

the concentration spike at Westmorland 

during the 19th hour,112 we note that 

ARB could have provided additional 

information to supplement the satellite 

imagery. Such information could 

include, but may not be limited to radar 

data and weather observations that note 

the presence of blowing dust in areas 

around the monitors. 

Finally, ICAPCD takes exception to 

our desire for better documentation 

regarding the investigation of other 

potential causes. In this regard, ARB 

made the following statement: 113

(ICAPCD) investigated emission generating 

activities during this episode, and found that 

PM10 emissions for BACM controlled sources 

were approximately constant before, during 

and after the event. The District determined 

that the * * * concentrations of PM10 * * * 

were instead primarily the result of windentrained dust * * * associated with a 

mesoscale convective system * * *. 

Although the preceding passage 

suggests that ICAPCD conducted an 


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114Proposal TSD, pp. 5–7. 

115Proposal TSD, pp. 7–8. 

116 General Preamble Addendum at 42012–42014. 

117 57 FR 18070, 18072. 

118See proposal TSD, pp. 8 and 14–15. 

119Moreover, as stated in the General Preamble 

Addendum at 42013, ‘‘any control measures that a 

commenter indicates during the public comment 

period is available for a given area should be 

reviewed by the planning agency.’’ 

120Proposal TSD, p. 14. 

active investigation of other emission 

generating activities on the day of the 

event, this claim is largely unsupported 

except for an interoffice memo included 

in Attachment H to the September NED. 

The memo states that various records 

were inspected in 2008 but that no 

inspections were conducted on the day 

of the event. We were thus left 

wondering how a file review conducted 

two years after the fact qualifies as an 

investigation of emission generating 

activities ‘‘during [the] episode’’ and 

how ICAPCD came to the somewhat 

substantial conclusion that emissions 

from BACM controlled sources were 

constant before, during, and after the 

event. 

E. OHV Controls 

OHV #1: ICAPCD believes that EPA 

should have concurred with all of the 

exceptional event requests associated 

with high winds as discussed in the 

Exceptional Events comments 

summarized in section II.D above. As a 

result, ICAPCD believes that windblown 

dust from open areas is not a significant 

source category in Imperial County, and 

therefore is not subject to the BACM 

requirement as part of the SIP. 

Response: In our proposed action on 

Regulation VIII, we explained why 

windblown dust from open areas is 

treated as a significant source category 

subject to BACM.114 We have not 

received information in the comments 

or elsewhere that changes this 

conclusion or the related decision to not 

concur with the State’s exceptional 

event requests for Imperial County. See 

also responses to Exceptional Events 

comments in section II.D above. 

OHV #2: CBD comments that BLM 

land is the largest PM10 source in 

Imperial County and should be subject 

to the same controls as adjacent land. 

CBD believes the Dust Control Plan 

(DCP) requirement for BLM land in Rule 

800 section F.5 is unenforceable, in 

conflict with the CAA, while other areas 

are subject to more stringent Regulation 

VIII requirements. 

In contrast, ICAPCD believes that Rule 

800’s DCP implements BACM, and that 

Rule 800’s exemption for BLM does not 

relax other Regulation VIII 

requirements. For example, Rule 800 

section F.5.c requires BLM’s DCP to be 

consistent with Rules 804 and 805 

except where otherwise prohibited, in 

which case section F.5.e requires all 

feasible control measures during offroad events. ICAPCD also notes that 

where there are such prohibitions, 

section F.5.d requires the DCP to 

discuss and implement ‘‘other possible 

control measures’’ and that Rule 800 

section D.3 requires the DCP to be 

submitted to ICAPCD, ARB and EPA for 

review and comment and to be updated 

every two years. 

ICAPCD believes BLM should be 

treated separately in Regulation VIII 

because there are many restrictions 

imposed by a variety of laws other than 

the CAA that apply to actions on 

Federal lands and that the District’s 

involvement in these issues would 

delay implementation of the PM control 

program on BLM lands. ICAPCD also 

believes that BLM should be treated 

separately because some Federal land 

uses preclude traditional dust controls 

and because BLM’s OHV areas are far 

from Imperial County populations. 

ICAPCD argues that even if Rule 800 

section F.5.c corresponds to 

requirements that are less effective than 

those of Rules 804 and 805, such lower 

stringency is both necessary and 

appropriate given the special nature of 

BLM lands. 

BLM agrees that many traditional 

BACM are not possible on Federal land 

because of the large expanses of desert 

ecosystems. BLM continues evaluating 

the DCP, however, which has led to 

closing areas and routes to vehicle use, 

restoring closed surfaces to natural 

conditions, hardening high traffic areas, 

posting and enforcing speed limits, 

educating desert users, and controlling 

dust from non-OHV activities. 

Response: BACM is required but has 

not been demonstrated for OHV activity 

on BLM land in Imperial County.115

EPA guidance explains that this 

demonstration should include 

evaluation and documentation of the 

technological and economic feasibility 

of potential control measures, including 

implementation of measures on a 

limited basis if full implementation is 

not feasible. As stated in our guidance, 

‘‘the documentation should compare the 

control efficiency of technologicallyfeasible measures, their energy and 

environmental impacts and the costs of 

implementation.’’ 116 ICAPCD’s 

demonstration should include careful 

consideration of analogous controls 

implemented on private lands in 

Imperial County and on public lands in 

Maricopa and Clark Counties and 

elsewhere, as well as controls 

recommended in EPA’s RACM 

guidance,117 and suggestions provided 

in our proposal 118 and comments on the 

proposal.119

The evaluation of technological 

feasibility may appropriately consider 

the alleged ‘‘special nature’’ of BLM 

lands. Such an evaluation, if conducted 

appropriately, may be sufficient to 

demonstrate that what constitutes 

BACM for BLM land in Imperial County 

is different from what constitutes BACM 

in other geographical areas and for 

private land in Imperial County. The 

information provided in the comments 

and Regulation VIII submittal, however, 

is not sufficient to support such a 

distinction. For example, ICAPCD and 

other commenters have not 

demonstrated how existing BLM 

controls implement BACM in the Plaster 

City areas, which are open to OHV 

activity at all times, and, if such 

controls do constitute BACM, why they 

cannot be incorporated into Regulation 

VIII and the SIP. 

Furthermore, with regard to CBD’s 

comment concerning the enforceability 

of DCPs, State and local requirements 

that implement BACM are subject to the 

enforceability requirement of CAA 

section 110(a). As we stated in our 

proposal, BACM has not been 

demonstrated for OHV sources because, 

among other things, none of the OHV 

restrictions are in regulatory form and 

submitted for inclusion in the SIP.120

OHV #3: OWD notes that California 

State Parks (CSP) manages OHV 

recreational activity in Imperial County 

at Heber Dunes State Vehicular 

Recreation Area, Ocotillo Wells SVRA, 

and in an interdepartmental joint 

management agreement at the Freeman 

Properties immediately north of Ocotillo 

Wells SVRA and east of Anza Borrego 

Desert State Park. OWD also notes that 

Ocotillo Wells SVRA alone represents 

approximately 85,000 acres of managed 

OHV recreational activity within 

Imperial County. While much of this 

land is designated trail riding only and 

is primarily defined by terrain 

constraints, OWD states that the 

majority of the area is designated open 

riding, where OHVs are not limited to 

defined trails. Rather than implement 

generalized BACM for OHV activity in 

Ocotillo Wells SVRA and other State 

Parks, OWD explains that it has adopted 

State mandated soil standards, a habitat 

monitoring system and other policies 

tailored for the case-by-case conditions 

found in each park unit. OWD believes 


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39380 Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 

121 ICAPCD Rule 804, sections B, C.29, E and F. 

122See also ‘‘Fugitive Dust Control Plan,’’ Bureau 

of Land Management El Centro Field Office, June 

29, 2006; ‘‘Fugitive Dust Control Plan,’’ Bureau of 

Land Management El Centro Field Office, January 

25, 2010 Draft; e-mail from Andrew Trouette (BLM) 

to Andrew Steckel (EPA), May 24, 2010. 

123 General Preamble Addendum at 42010–42014. 

124 Id. at 42014. 

that fencing, and then maintaining, a 

vast amount of land is neither 

economically nor environmentally 

feasible. OWD also believes that 

watering, laying gravel, or applying a 

chemical solution to the miles of trails 

that would be encompassed is neither 

economically nor environmentally 

feasible. In contrast, CBD argues that 

further implementation of Rule 804 and 

additional OHV controls may be needed 

for State lands including the Ocotillo 

Wells SVRA in order to attain air quality 

standards. 

Response: Rule 804 requires all 

persons, including public entities such 

as CSP, with jurisdiction over open 

areas in Imperial County with over 

1,000 square feet of disturbed surface 

area to maintain a stabilized surface, 

limit opacity to 20% and comply with 

at least one of the following: (a) Apply 

and maintain water or dust suppressant 

to all unvegetated areas; (b) establish 

vegetation on all previously disturbed 

areas; or (c) pave, gravel or chemically 

stabilize.121 OWD’s comment 

acknowledges that CSP has jurisdiction 

over open areas with over 1,000 square 

feet of disturbed surface area within 

Imperial County. Because these areas 

are not addressed by exemptions in Rule 

800 section E or Rule 804 section D,122

these areas must comply with the above 

requirements. However, from OWD’s 

comment, CSP is clearly not currently 

complying with these requirements. As 

a result of the inclusion of Rule 804 into 

the SIP, these requirements will become 

federally enforceable upon the effective 

date of this final action, and such 

noncompliance could result in civil 

action under CAA section 113 and/or 

304. 

OHV #4: Various commenters argue 

that controls suggested in our proposal 

as part of the BACM analysis that 

ICAPCD still needs to conduct would 

not reduce PM10 impacts from OHVs in 

Imperial County. 

• Many commenters oppose further 

restrictions during the summer, 

claiming that OHV activity and 

emissions are very low in Imperial 

County due to high temperatures and 

existing red sticker regulations that 

restrict certain vehicles during the 

summer. BLM concurs that OHV use is 

already lowest in the summer, and 

ICAPCD also concurs and argues that 

OHV restrictions during the summer 

would burden public resources without 

reducing emissions. However, one 

commenter (0100) states that OHV use 

during summer nights is a great activity 

which creates minimal dust because 

travel is at low speeds on established 

trails. Another commenter (0204) 

indicates that many promoters run OHV 

races at night that allow for fun 

recreational activity in cooler 

temperatures. This commenter believes 

night races decrease risks to spectators 

which is more important than reducing 

dust emissions. Some commenters also 

observe that wind events can occur in 

the summer and cause severe dust days. 

By contrast, another commenter (0146) 

believes that the desert is mainly dry 

and free of wind in the summer. 

• ICAPCD believes that restrictions 

like those in place in Arizona, during 

pollution advisory days, would be 

unproductive because high-PM forecasts 

in Imperial County only occur on highwind days when OHVs are not used. 

• Many commenters (e.g., 0094) 

observe that OHVs are already restricted 

to certain areas, causing crowding and 

injuries. ICAPCD notes that OHVs are 

restricted to 11% of local BLM land, and 

additional closure would probably shift 

OHV activity and emissions to other 

areas nearby. OWD also believes EPA’s 

action could force OHV users to other 

areas, causing environmental effects 

outside Imperial County. 

• ICAPCD comments that EPA cannot 

demonstrate that OHV restrictions 

would reduce windblown dust 

emissions because there is no basis for 

EPA’s contention that surfaces impacted 

by OHVs would form any appreciable 

crust given Imperial’s low level of rain. 

OWD similarly comments that crust 

repair would be difficult due to the 

limited rain in Imperial County. 

Another commenter (0120) believes that 

restricting OHV areas could increase 

PM10 emissions because more vehicles 

in smaller areas would disturb more soil 

that cannot crust over. See also 

comment EE #8. 

• OWD comments that fencing, 

watering, gravelling or chemically 

stabilizing miles of OHV areas is not 

feasible. For example, water resources 

are scarce and modification of existing 

OHV trails could alter natural drainage 

patterns and increase erosion. 

Response: EPA believes that some of 

the information provided in these 

comments could be relevant 

considerations in the comprehensive 

BACM analysis that ICAPCD needs to 

undertake in order to determine what 

controls constitute BACM for OHV 

activity in Imperial County. However, in 

general, the comments are conclusory 

and not supported by data, detailed 

information, or other evidence that 

would be required for an adequate 

BACM demonstration under our 

guidance.123 As summarized in the 

guidance: 

In summary, the State must document its 

selection of BACM by showing what control 

measures applicable to each source category 

(not shown to be de minimis) were 

considered. The control measures selected 

should preferably be measures that will 

prevent PM–10 emissions rather than 

temporarily reduce them. The documentation 

should compare the control efficiency of 

technologically-feasible measures, their 

energy and environmental impacts and the 

costs of implementation.124

Furthermore, contradictions in the 

comments also serve to illustrate that 

there are fundamental factual questions 

that need to be addressed about the 

amount of OHV activity during different 

seasons and different times of the day, 

and the best ways to mitigate emissions 

from such activities. At this juncture, 

ICAPCD has not conducted an adequate 

analysis. 

OHV #5: Many commenters (e.g., 0108 

and OWD) state that further OHV 

restrictions would hurt the already 

depressed local economy, and cite 

potential effects on local business 

owners, farmers, land owners, OHV 

users, race car owners, construction 

companies, ranchers, the Imperial 

Irrigation District and others. 

Commenters observe that recreational 

activities generate substantial revenue 

(0196), and one (0156.1) claims that 

OHVs have contributed several hundred 

million dollars to the local economy. 

ICAPCD believes that the economic cost 

of OHV activity restrictions is far more 

than appropriate for BACM. For 

example, ICAPCD estimates that closing 

the Imperial Sand Dunes Recreational 

Area would cost $370,000 to $640,000 

per ton of PM10 reductions. ICAPCD 

provides specific references to support 

its cost/benefit analysis. Another 

commenter (0219) similarly believes 

that additional OHV restrictions, such 

as closing land in the summer, would 

provide few benefits given the relatively 

small emissions from OHVs, but would 

have significant economic impacts. 

Response: We appreciate the value of 

OHV tourism to the local economy, and 

agree that ICAPCD must consider 

economic feasibility in BACM analyses 

evaluating potential controls for 

emissions from OHV activities. 

However, the relevant inquiry in the 

economic feasibility analysis required in 

BACM determinations is ‘‘the cost of 

reducing emissions from a particular 

source category and costs incurred by 


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Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 39381 

125 General Preamble Addendum at 42013. 

126See CAA section 116. 

127See, e.g., proposal TSD, pp. 8 and 13–15. 

128Submitted as Exhibit D to Comite comment 

letter. 

129See, e.g., General Preamble Addendum at 

42012–42013. 

130Proposal TSD, p. 16, and General Preamble 

Addendum at 42013. 

similar sources that have implemented 

emission reductions.’’ 125 In this case, 

the cost of OHV restrictions on OHV 

area owners (i.e., the State and Federal 

governments) and users would appear to 

be minimal, and the secondary 

economic impacts on businesses 

supporting OHV tourism are not 

relevant to the required BACM analysis. 

In any event, ICAPCD needs to evaluate 

the economic feasibility of potential 

controls, including those adopted in 

other areas, in determining what 

controls constitute BACM in this area. 

OHV #6: EcoLogic asks EPA to clarify 

whether and where OHV restrictions are 

being contemplated in the Imperial 

Sand Dunes Recreation Area and 

elsewhere and to what extent OHV 

activity on Federal land is subject to the 

proposed rule or ICAPCD jurisdiction. 

EcoLogic and another commenter (0141) 

also request clarification on which of 

the 250 square miles of OHV areas EPA 

is asking ICAPCD to evaluate for closure 

and what the basis is for claiming that 

these areas are likely to impact 

populations. 

Response: State and Federal agencies 

are subject to many local requirements 

including Regulation VIII and other air 

quality related ICAPCD rules.126 Our 

proposal explains why ICAPCD must 

analyze whether additional controls 

(potentially including closure) are 

appropriate for public land in Imperial 

County open to OHVs, which ICAPCD 

estimates at over 250 square miles.127

We did not identify any specific 

geographic areas needing more or less 

analysis or control or having more or 

less impact on populations. Rather, in 

the analysis ICAPCD should consider all 

potential available OHV controls in all 

OHV areas in Imperial County and, 

where feasible, should consider whether 

different areas within the County have 

different impacts on populations or 

areas with exceedances of the NAAQS. 

OHV #7: Several commenters believe 

additional OHV restrictions should be 

analyzed and/or incorporated into 

Regulation VIII. CBD believes that OHV 

requirements in Rule 804 are too vague 

to be enforceable as required by CAA 

section 110(a), particularly regarding 

BLM and State managed land. CBD 

believes Regulation VIII should require 

specific BACM measures, such as 

restrictions on the number of OHV 

vehicles operating each day, to improve 

emission quantification and control. 

CBD believes such carrying capacity 

caps or other restrictions should also 

address weather conditions when they 

exacerbate PM10 emissions, such as 

during windy weather and the summer. 

Comite comments that ICAPCD should 

analyze whether OHV permit 

requirements, such as those that are 

required in San Bernardino County, 

should be required in Imperial County. 

Comite also believes that ICAPCD 

should analyze controls described in the 

California State Parks Off-Highway 

Motor Vehicle Recreation Division’s 

2008 Soil Conservation Standard and 

Guidelines.128 Lastly, instead of 

decreasing the size of OHV areas, one 

commenter (0120) suggested rotating 

OHV areas to help surface crust 

formation. 

Response: The commenters as a group 

make constructive suggestions that 

would be appropriate for consideration 

in a comprehensive evaluation of BACM 

for this source category. We believe 

ICAPCD should analyze all potential 

available OHV controls to meet the 

CAA’s BACM requirement, including 

those mentioned in the comments and 

those adopted in other areas, pursuant 

to EPA guidance.129

F. Definition of Disturbed Surface (DS) 

DS #1: ICAPCD believes the term 

‘‘disturbed surface’’ is self-evident and 

that no questions have been raised about 

it since rule adoption. ICAPCD believes 

Rule 804 is clear that an area is deemed 

disturbed if it shows any sign of manmade disturbance (e.g., vehicle traffic) 

and the owner/operator cannot prove 

that the area meets the characteristics of 

a stabilized surface. ICAPCD is willing 

to define this term more clearly during 

the next revision to Rule 101, but 

strongly objects to EPA disapproving 

Regulation VIII on this basis. In contrast, 

CBD supports EPA’s concerns regarding 

this definition in Regulation VIII, and 

further believes the definition should be 

tailored to Imperial Valley and 

explicitly include open areas on BLM 

land that emit significant PM10

including the Algodones Dunes. In this 

regard, CBD suggests specific edits to 

SJVUAPCD’s analogous rule. 

Response: We believe the explanation 

provided in ICAPCD’s comment is a 

logical interpretation of the undefined 

term in its regulation. However, we also 

believe that alternate definitions are 

possible (such as that recommended by 

CBD in its comment), and it is common 

practice to define all terms used in rules 

that are needed in order to ensure 

clarity and enforceability. We encourage 

ICAPCD to clarify its regulation by 

including an appropriate definition of 

this critical term and to consider CBD’s 

recommendations for the wording of the 

rule. 

G. Unpaved Road (UR) Controls 

UR #1: ICAPCD projects that control 

of unpaved non-farm roads provides 

55% of Regulation VIII’s emission 

reductions. ICAPCD believes this 

demonstrates a good faith effort to 

reduce PM10 emissions from road 

stabilization, and asserts that the County 

is trying to increase funding for such 

projects. ICAPCD states that the $2 

million/year available to the County 

Department of Public Works (PWD) for 

road maintenance and stabilization 

reflects great needs and low availability 

of public funds in the County. 

According to ICAPCD, this budget is for 

maintenance of 1,350 miles of paved 

roads which require resurfacing every 

10–15 years, or 90 miles of extensive 

maintenance each year. Thus, ICAPCD 

argues that allocation of 9% of this 

budget to stabilize 19 miles of unpaved 

road represents, contrary to EPA’s 

assertion, the most expedited schedule 

possible with the present level of 

available funding. 

Response: Where economic feasibility 

of control depends on public funding, 

EPA will consider past funding and the 

future availability of funding sources to 

determine if a good faith effort is being 

made to implement BACM 

expeditiously.130 The fact that unpaved 

road controls provide 55% of Regulation 

VIII’s estimated emission reductions is 

not in itself sufficient to demonstrate 

good faith efforts to control road dust 

expeditiously. Alternatively, for 

example, this high percentage of the 

total amount of reductions could occur 

if other sources are under-controlled or 

are less feasible to control. Nonetheless, 

EPA believes that some of the 

information ICAPCD provides in its 

comment on this point could help to 

demonstrate a good faith effort to 

control road dust expeditiously. Given 

ICAPCD and Imperial County’s limited 

resources, we do not believe this 

analysis needs to be exhaustive, but it 

should be more thorough and 

documented than presented in the 

Regulation VIII submittal and this 

comment. For example, ICAPCD 

indicates in this comment that the 

County is trying to increase funding for 

road stabilization but provides no 

documentation to help establish this 

point. Nor has ICAPCD explained how 

the road stabilization budget was 

derived in light of various Federal, 


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131See proposal TSD, p. 16. 

132See id., p. 9. 

133 Id., p. 11. 

134 2005 BACM analysis, chapter 4, and 2009 

PM10 SIP, table 4.2. 

135 2005 BACM analysis, p. 21. 

136For example, a 40% opacity plume in the 

middle of a large property that disperses to 0% 

opacity by the property fence-line violates 

ICAPCD’s rule but not SCAQMD’s. Conversely, a 

10% opacity plume that disperses to 5% opacity by 

the fence-line violates SCAQMD’s rule but not 

ICAPCD’s. 

State, and local (including local 

Measure D) funding sources for public 

works construction and maintenance, or 

otherwise provided the demonstration 

contemplated by the relevant EPA 

guidance.131

UR #2: ICAPCD disagrees with EPA 

that there could be problems enforcing 

Rule 805 section E.7. As evidence, 

ICAPCD explains that Imperial County 

PWD is meeting its commitment to 

implement its submitted plan, which 

includes stabilizing different unpaved 

roads each year and maintaining all 

stabilized roads as intended by the rule. 

Response: CAA section 110(a) 

requires that control measures be 

enforceable. While Rule 805 section E.7 

requires that a compliance plan be 

submitted to ICAPCD, the rule is not 

clear about the specific requirements of 

the plan (i.e., that the County must 

stabilize different roads each year and 

must maintain all stabilized roads) and 

does not contain a mandate that the 

terms of the plan be carried out. 

Evidence that Imperial County PWD is 

in fact currently implementing the plan 

is not sufficient to ensure enforceability 

as required by the CAA.132 ICAPCD 

should revise the rule to clarify this 

section consistent with enforceability 

requirements of CAA section 110(a). 

UR #3: Comite believes that ICAPCD 

should incorporate additional 

restrictions into Regulation VIII, 

including property line visible 

emissions (VE) limits such as those 

adopted by Maricopa County and 

SCAQMD, dust controls for unpaved 

roads subject to Rule 805 section E.7, 

and other more stringent requirements 

adopted by SCAQMD, SJVUAPCD, 

Maricopa County and Clark County. 

Response: ICAPCD’s analysis of 

BACM did consider controls 

implemented in other areas, including 

those adopted by SCAQMD, SJVUACPD, 

and Maricopa and Clark Counties. Our 

proposal TSD recommends several 

specific controls from these areas for 

further consideration by ICAPCD, 

including imposition of a fence-line 

opacity standard.133

However, with the exception of the 

deficiencies identified in our proposal, 

we believe that ICAPCD sufficiently 

analyzed controls in other areas for 

potential BACM.134 For example, 

ICAPCD explains that SCAQMD has 

only a 0% fence-line opacity standard, 

whereas ICAPCD and other agencies 

with adopted rules approved as BACM 

all have a similar general 20% opacity 

standard applicable everywhere, and 

not just at the fence-line.135 ICAPCD 

claims that SCAQMD’s 0% fence-line 

standard is less stringent than a general 

20% standard. While it is difficult to 

compare the two standards,136 we do 

not have evidence that SCAQMD’s 

standard is more stringent than the 

general standard used by ICAPCD and 

by other air districts. 

UR #4: One commenter (0154) states 

that it is not feasible or cost effective to 

eliminate all dust from dirt roads. 

Response: We agree with this 

comment. Neither Regulation VIII nor 

our proposal or this final action assumes 

that dust emissions can be completely 

eliminated from farm and non-farm dirt 

roads. 

H. Border Patrol (BP) Controls 

BP #1: ICAPCD comments that Rule 

800 section F.6.c does not explicitly 

exempt BP from fugitive dust controls, 

but requires BP to control dust from 

roads it owns/operates consistent with 

Rule 805 except where inconsistent 

with BP’s authority or mission. ICAPCD 

indicates that, while BP does not own 

any roads, it uses public roads to 

accomplish its mission, and some roads 

adjacent to the border are used 

exclusively by BP. ICAPCD states that 

most of these roads are below Rule 805’s 

applicability threshold, are located in 

remote areas that are for the most part 

restricted to BP vehicles, and PM10

controls are not feasible and are 

inconsistent with BP’s mission. ICAPCD 

explains that although BP neither owns 

nor operates these roads, BP is 

committed to implement PM10 controls 

such as vehicle speed restrictions and 

access controls. ICAPCD indicates that 

since adoption of Regulation VIII, BP 

has submitted two productive DCPs. 

Therefore, ICAPCD disagrees with EPA’s 

recommendation to remove or narrow 

the exemption for BP activities, and 

proposes to continue addressing BP 

through a DCP requirement to insure 

that BP continues controlling fugitive 

dust. 

Response: First, we note that nothing 

in our proposal affects Regulation VIII’s 

requirement for BP to develop and 

implement DCPs pursuant to Rule 800 

sections F.6.a and F.6.b. However, 

ICAPCD’s explanation is unclear as to 

whether or not BP operates any roads 

subject to the rule. If ICAPCD can 

support its assertion that BP neither 

owns nor operates such roads, the 

exemption in Rule 800 section F.6.c. is 

simply unnecessary and should be 

removed. If BP does own or operate 

such roads, we continue to believe that 

the exemption is unnecessarily broad 

and should be removed or narrowed and 

demonstrated to be consistent with 

BACM requirements. 

ICAPCD offers no evidence or 

explanation to support its contention 

that Rule 805 requirements are 

potentially inconsistent with BP’s 

authority and/or mission. We also note 

that BP has not raised concerns with our 

proposal, although we informed BP of it 

before publication. EPA appreciates 

BP’s efforts to limit PM10 pollution 

through DCPs. Our concern, however, is 

with ICAPCD’s Regulation VIII 

submittal and the lack of clarity in, and 

analysis to support, the actual 

provisions in Regulation VIII intended 

to govern these activities. 

BP #2: OWD comments that BP 

frequently goes off-road within Ocotillo 

Wells SVRA, beyond OWD’s control. 

Response: Rule 804 section E imposes 

requirements on owners of open areas 

such as Ocotillo Wells SVRA regardless 

of who owns vehicles driving on the 

open areas. Nothing in our proposal 

would affect these existing ICAPCD 

requirements. 

I. Unpaved Farm Roads and Traffic 

Areas (UFRTA) Controls Introduction 

The comments summarized in this 

section and sections II.J and K relate to 

ICAPCD Rule 806, Conservation 

Management Practices. In discussing 

our proposal regarding Rule 806, a 

number of these comments address 

various aspects of analogous rules 

adopted by State and local agencies in 

California and Arizona for controlling 

PM10 from agricultural sources. All of 

these rules are menu-based and as such 

divide the control measures, known as 

conservation management practices 

(CMPs) or best management practices 

(BMP), into three or more menus known 

as ‘‘categories.’’ We provide the 

following information on these rules as 

an introduction to inform our responses 

to the comments in this section and 

sections II.J and K. 

ICAPCD Rule 806, Conservation 

Management Practices, is a menu-based 

rule that has four categories: 

• Land preparation and cultivation. 

• Harvesting. 

• Unpaved roads. 

• Unpaved traffic areas. 

All persons who own or operate an 

agricultural operation site of forty acres 

or more are required to implement one 


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137SJVUAPCD’s jurisdiction includes the entire 

counties of San Joaquin, Stanislaus, Merced, 

Madera, Fresno, Tulare, and Kings and part of Kern 

County. SJVUAPCD does not include the parts of 

East Kern that are not in the San Joaquin Valley Air 

Basin. See 40 CFR 81.305. 

138The Phoenix Planning Area includes Maricopa 

County and a portion of Pinal County. See 40 CFR 

81.303. 

139See section 1 and 2 of GBUAPCD Rule 502. 

Also see 40 CFR 81.305. 

140SCAQMD’s jurisdiction includes the South 

Coast Air Basin and the Coachella Valley Planning 

Area. For a description of the boundaries of the Los 

Angeles-South Coast Air Basin Area and the 

Coachella Valley Planning Area, see 40 CFR 81.305. 

The South Coast Air Basin includes all of Orange 

County and the more populated portions of Los 

Angeles, San Bernardino, and Riverside Counties. 

The Coachella Valley Planning Area includes 

central Riverside County in the Salton Sea Basin. 141Proposal TSD, pp. 8–9. 

CMP from each of these categories. 

Table 3 summarizes the relevant 

categories from Rule 806 and the other 

menu based rules to which we refer: 

TABLE 3 

State or local agency Rule Area Categories for on-field 

agricultural operations 

Categories for unpaved 

Ag. roads and traffic 

areas 

Imperial County APCD (ICAPCD) 806 .................................. Imperial County .............. › Land Preparation and 

Cultivation (including 

tillage).

› Unpaved Roads. 

› Harvesting .................. › Unpaved Traffic Areas. 

San Joaquin Valley Unified 

APCD (SJVUAPCD).

4550 ................................ San Joaquin Valley Planning Area.137› Land Preparation and 

Cultivation (including 

tillage).

› Unpaved Roads. 

› Harvest ....................... › Unpaved Traffic Areas. 

› Cropland—Other.

Arizona Department of Environmental Quality (ADEQ).Arizona Administrative 

Code (A.A.C) R18–2– 

610 and R18–2–611.

Phoenix Planning 

Area.138

› Tillage and Harvest .... › Noncropland. 

› Cropland.

Great Basin Unified APCD 

(GBUAPCD).

502 .................................. Alpine, Inyo, and Mono 

Counties.139

› Land preparation ........ › Unpaved Roads. 

› Harvest ....................... › Unpaved Traffic Areas. 

› Other Cultural Practices.

South Coast AQMD ..................... Rule 403 And Agricultural Handbook.South Coast Air 

Basin.140

› Active Conservation 

Practices.

› Unpaved Roads. 

› Inactive Conservation 

Practices.

South Coast AQMD ..................... Rule 403 And Coachella 

Valley Agricultural 

Handbook.

Coachella Valley Planning Area.› Active Conservation 

Practices.

› Unpaved Roads. 

› Inactive Conservation 

Practices.

We also refer below to SJVUAPCD’s 

Rule 8081, Agricultural Sources, which 

has opacity and stabilization 

requirements for high traffic agricultural 

unpaved roads and traffic areas. 

UFRTA #1: Comite believes that 

California has not demonstrated why 

agricultural paved and unpaved roads 

should be subject to less stringent 

requirements than other roads in 

Imperial County (i.e., those subject to 

Rule 803 regarding track-out/carry-out 

and Rule 805) and cites San Joaquin 

Valley where such roads must meet 

CMPs as well as general requirements. 

In contrast, ICAPCD and the Farm 

Bureau believe Regulation VIII is more 

stringent regarding unpaved farm roads 

and traffic areas than analogous rules in 

other areas even though Imperial 

County farm roads and traffic areas are 

not subject to opacity limits. These 

latter commenters note that Rule 806 

requires CMPs for all unpaved roads 

and traffic areas regardless of vehicle 

trips per day (VTD), unlike SJVUAPCD 

Rule 4550. COLAB also explains that 

ICAPCD Rule 806 was designed to 

address all unpaved roads by applying 

to parcels greater than 40 acres (97% of 

farmland in Imperial County) compared 

to SJVUAPCD’s Rule 4550 which 

addresses roads on parcels larger than 

100 acres (91% of farmland in the San 

Joaquin Valley). Lastly, ICAPCD and the 

Farm Bureau assert that most private 

unpaved farm roads are less used and 

are therefore below Rule 805’s 50 VTD 

threshold. Regardless of VTD, however, 

these latter commenters argue that 

owners of these roads must implement 

Rule 806 CMPs. 

Response: EPA’s proposal noted that 

ICAPCD has not demonstrated BACM 

for unpaved farm roads and traffic areas 

because of the exemption in Rule 805 

section D.2 from opacity and 

stabilization requirements applicable to 

non-agricultural operation sites. EPA 

further noted that SJVUAPCD does not 

provide such an exemption, and 

ICAPCD had not justified such an 

exemption.141

ICAPCD and other commenters do not 

offer evidence that Regulation VIII is as 

stringent as comparable controls in this 

regard, but instead claim that Regulation 

VIII is more stringent in other respects. 

For example, no commenter disputes 

our conclusion that an unpaved farm 

road with 75 VTD would be subject to 

opacity standards in SJVUAPCD’s Rule 

8081 but not in ICAPCD’s Regulation 

VIII. However, ICAPCD and others argue 

that the applicability threshold for 

unpaved farm roads subject to Rule 806, 

for example, is more stringent than 

SJVUAPCD’s analogous requirements. 

Because opacity and surface 

stabilization requirements on heavilyused farm roads and traffic areas are 

being implemented in other areas, we 

believe that, absent an adequate 

explanation, these requirements are at 

least presumptively BACM for this 

source category in Imperial County. 

Accordingly, these controls should be 

evaluated as potential BACM by 

ICAPCD. However, as stated previously, 

ICAPCD may consider conditions 


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142Although ICAPCD refers to requirements 

adopted by Maricopa County in its comments, 

Arizona’s rules, A.A.C. R18–2–610 and R18–2–611, 

for controlling PM–10 from agricultural sources 

apply to some sources beyond the boundaries of 

Maricopa County. 

143As noted in Table 3 above, SCAQMD’s Rule 

403 has requirements for agricultural activities that 

apply to both the South Coast Air Basin and 

Coachella Valley Planning Area. 144EPA approved SJVUAPCD Rule 4550 in 2006, 

not in 2004. See 71 FR 7683. EPA approved a 

commitment for the San Joaquin Valley CMP 

Program in 2004. See 69 FR 30006. 145See 75 FR 8008, 8011–8012. 146See SJVUAPCD Rule 4550 section 6.3 and 6.4 

and GBUAPCD Rule 502 section 6.3 and 6.4. 147See SJVUAPCD Rule 4550 section 6.2 and 

SJVUAPCD ‘‘List of Conservation Management 

Practices.’’ See also GBUAPCD Rule 502 section 6.2 

and, for example, GBUAPCD Supplemental 

Application Form for Alfalfa. See also 

‘‘Conservation Management Practices for Farms in 

Inyo, Mono and Alpine Counties, Program 

Description and Plan Application Forms,’’ 

December 19, 2008, Great Basin Unified Air 

Pollution Control District, at http:// 

www.gbuapcd.org/farm/ 

CMPprogramdescriptionandforms.pdf. 

148 General Preamble Addendum at 42010 and 

42012. 

149 2007 Census of Agriculture, California, State 

and County Data, and 2007 Census of Agriculture, 

Arizona, State and County Data, United States 

Department of Agriculture, National Agricultural 

Statistics Service. See http:// 

www.agcensus.usda.gov/Publications/2007/ 

Full_Report/Volume_1,_Chapter_2_County_Level/ 

California/cav1.pdf and http:// 

www.agcensus.usda.gov/Publications/2007/ 

Full_Report/Volume_1,_Chapter_2_County_Level/ 

Arizona/azv1.pdf. 

150See footnote 141 above. The census data in 

Table 4 are for all of Kern County. 

151Of all the counties included in SCAQMD, 

Riverside County has the largest acreage of 

harvested cropland. According to the 2007 Census 

of Agriculture, Orange County has 7,846 acres of 

harvested cropland, Los Angeles County has 25,829 

acres of harvested cropland, San Bernardino County 

has 27,516 acres of harvested cropland, and 

Riverside County has 163,783 acres of harvested 

cropland. 2007 Census of Agriculture, California, 

State and County Data, United States Department of 

Agriculture, National Agricultural Statistics 

Service. See http://www.agcensus.usda.gov/ 

Publications/2007/Full_Report/ 

Volume_1,_Chapter_2_County_Level/California/ 

cav1.pdf. 

specific to Imperial County in a revised 

BACM evaluation for unpaved roads 

and traffic areas, as appropriate. 

We also agree with Comite that it is 

not clear why Rule 803 section D.1 

exempts farm roads and traffic areas 

from certain carry-out and track-out 

requirements that apply to similar nonfarm roads. We encourage ICAPCD to 

consider removing this exemption, 

although such a rule modification is not 

mandated by the CAA at this time 

because carry-out/track-out has not been 

identified as a significant source 

category subject to the BACM 

requirement. 

UFRTA #2: Comite believes that Rule 

806’s CMPs are not sufficiently specific 

regarding agricultural unpaved roads 

and traffic areas. In contrast, ICAPCD 

comments that Rule 806 section F.6 

requires CMP plans to include other 

relevant information, which gives 

ICAPCD authority to require adequate 

specificity. COLAB also comments that 

the CMP forms provided in the rule are 

examples and if the relevant 

information was provided the form 

could be changed. 

Response: Issues raised regarding 

specificity of CMPs for unpaved roads 

and traffic areas are similar to issues 

raised regarding the specificity of CMPs 

for other agricultural operations. See 

response to comment AL #3 below. 

J. Agricultural Land Controls (AL) 

See Introduction in section II.I above. 

AL #1: ICAPCD comments that Rule 

806’s CMP requirements are similar to 

requirements adopted by SJVUAPCD, 

Maricopa County 142 and SCAQMD,143

and are directly based on SJVUAPCD 

requirements that EPA approved as 

BACM in 2004, citing 69 FR 30035.144

ICAPCD asserts that the individual 

CMPs in Rule 806 are similar to those 

found in SJVUAPCD Rule 4550 and 

GBUAPCD Rule 502 and concludes that 

the only differences in the rules are due 

to differences in local agricultural 

practices. The Farm Bureau also states 

that there is little difference between 

GBUAPCD and ICAPCD control 

measures. 

Response: We agree that many 

individual CMPs and requirements in 

the rules outlined in Table 3 are similar. 

However, this overall similarity does 

not affect the two specific BACM 

deficiencies in ICAPCD Rule 806 for 

tilling and harvesting emissions 

identified in our proposed action.145

One of these deficiencies concerns the 

lack of sufficiently defined requirements 

in contrast to the application submittal 

and review processes in the SJVUAPCD 

and GBUABCD rules that insure more 

effective implementation and 

enforcement of the requirements.146 The 

other deficiency is related to the number 

of CMPs required by Rule 806. Rule 806 

section E requires one CMP from the 

‘‘land preparation and cultivation’’ 

category and one CMP from the 

‘‘harvesting’’ category, while SJVAPCD 

Rule 4550 requires an additional CMP 

from the ‘‘cropland-other’’ category. 

GBUAPCD Rule 502 also requires that 

one CMP each be selected from the 

‘‘land preparation and cultivation,’’ 

‘‘harvest,’’ and the ‘‘other cultural 

practices’’ categories.147

AL #2: ICAPCD believes that EPA 

disregards that Imperial County crops 

are irrigated, and that continued 

irrigation and conditioning of soil 

dramatically reduce its potential for 

both entrained and windblown 

emissions. ICAPCD believes this fact 

must be considered when comparing 

Rule 806 to rules in other areas. 

Response: As stated previously above, 

EPA agrees that it is appropriate to 

consider conditions specific to an area 

when evaluating potential BACM.148

However, most of the harvested 

cropland in other areas subject to 

comparable requirements is also 

irrigated. The following table shows 

data from the 2007 Census of 

Agriculture 149 for the total acres of 

harvested cropland and the acres of 

irrigated harvested cropland in relevant 

counties in California and Arizona. 

Imperial County and the counties in the 

SJVUAPCD 150 are included. Riverside 

County in California 151 and Maricopa 

County in Arizona are also included. 

TABLE 4 

County, State 

Total harvested 

cropland 

(acres) 

Irrigated 

harvested 

cropland 

(acres) 

Imperial, CA ..................................................................................................................................................... 375,904 375,167 

Maricopa, AZ ................................................................................................................................................... 190,182 189,141 

Riverside County, CA ...................................................................................................................................... 163,783 158,437 

San Joaquin County, CA ................................................................................................................................. 444,670 426,670 

Stanislaus, CA ................................................................................................................................................. 307,992 297,053 

Merced, CA ...................................................................................................................................................... 466,304 458,017 

Madera, CA ...................................................................................................................................................... 264,767 260,596 

Fresno, CA ....................................................................................................................................................... 978,948 960,215 


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152For instance, one of the CMPs that is both in 

the ‘‘land preparation and cultivation’’ category in 

Rule 806 section E.1 and the ‘‘harvesting’’ category 

in section E.2 is ‘‘equipment changes/technological 

improvements’’ which is defined in section C.15 as 

‘‘To modify the equipment such as tilling; increase 

equipment size; modify land planning and land 

leveling; match the equipment to row spacing; 

granting to new varieties or other technological 

improvements. It reduces the number of passes 

during an operation, thereby reducing soil 

disturbance.’’ This definition is too broad to ensure 

enforceability. Moreover, because there is no 

mechanism to narrow the definition for a particular 

agricultural operation, a CMP may be implemented 

in a manner less stringent than a BACM level of 

control. In a similarly broad fashion, Rule 806 

section C.34 defines ‘‘speed limits,’’ a CMP in both 

the ‘‘unpaved roads’’ category in section E.3 and the 

‘‘unpaved traffic areas’’ category in section E.4, as 

‘‘enforcement of speeds that reduce visible dust 

emissions. The dust emissions from unpaved roads 

are a function of speed, meaning reducing speed 

reduces dust.’’ However, an appropriate speed limit 

or range of speed limits is not specified or 

otherwise insured. 

153See 75 FR 8008, 8011–8012. 

154Proposal TSD, pp. 5–6. 

155Proposal TSD, p. 10, footnote 25. 

156SJVUAPCD Rule 4451, Valves, Pressure Relief 

Valves, Flanges, Threaded Connections and Process 

Drains at Petroleum Refineries and Chemical Plants, 

amended April 20, 2005. 

157See SJVUAPCD Rule 4550 section 6.2 and 

SJVUAPCD ‘‘List of Conservation Management 

Practices.’’ See also GBUAPCD Rule 502 section 6.2 

and, for example, GBUAPCD Supplemental 

Application Form for Alfalfa. See also 

‘‘Conservation Management Practices for Farms in 

Inyo, Mono and Alpine Counties, Program 

Description and Plan Application Forms,’’ 

December 19, 2008, Great Basin Unified Air 

Pollution Control District, at http:// 

www.gbuapcd.org/farm/ 

CMPprogramdescriptionandforms.pdf. 

TABLE 4—Continued 

County, State 

Total harvested 

cropland 

(acres) 

Irrigated 

harvested 

cropland 

(acres) 

Kings, CA ......................................................................................................................................................... 419,964 419,080 

Tulare, CA ........................................................................................................................................................ 560,320 540,887 

Kern, CA .......................................................................................................................................................... 764,929 756,645 

Thus, the mere fact that crops are 

grown using irrigation in Imperial 

County does not in and of itself justify 

different standards for BACM. 

AL #3: ICAPCD comments that Rule 

806 section F.6 specifies that the CMP 

plan shall include ‘‘other relevant 

information as determined by the 

ICAPCD,’’ which gives ICAPCD 

authority to modify the CMP plans to 

specify frequency of CMP applicability. 

Therefore ICAPCD believes a 

mechanism is in place in the rule for 

modification of CMPs to provide such 

details, and therefore this should not be 

a basis for disapproval of Regulation 

VIII as BACM. ICAPCD notes its 

commitment to modify the CMP plans 

to provide such details. 

Response: As noted by ICAPCD, Rule 

806 section F.6 provides a mechanism 

that could be used by ICAPCD to 

provide greater specificity. However 

there is no required process in the rule 

for sources to provide such information 

to ICAPCD or for ICAPCD to review the 

CMPs and/or to require revision of the 

CMPs that sources have chosen to 

implement. Under section F, sources are 

only required to prepare a plan 

containing minimal information and to 

maintain a copy of the plan. Thus the 

CMPs would continue to be broadly 

defined unless or until ICAPCD 

proactively determines that greater 

specificity is needed. Absent such vital 

details, it would be difficult for 

regulated entities to know precisely 

what is required of them to comply with 

a BACM level of control, and it would 

be difficult for ICAPCD, EPA, or others 

to enforce these requirements.152 In 

contrast, SJVUAPCD Rule 4550 section 

5 requires sources to prepare and submit 

a CMP application to the District for 

approval and section 6 requires the 

District to evaluate and either approve 

or disapprove the application in writing. 

GBUAPCD Rule 502 sections 5 and 6 

contain substantially identical 

requirements. Such requirements 

provide a mandatory process that is far 

more likely to ensure that the CMPs are 

implemented and enforceable at a 

BACM level of control than the 

provision in ICAPCD Rule 806. 

Finally, even if ICAPCD were to 

routinely exercise its discretionary 

authority in Rule 806 to specify the 

frequency of CMP applicability, the 

deficiency noted in our proposed action 

related to lack of CMP specificity 

extends beyond the issue of 

frequency.153

AL #4: ICAPCD claims that BACM 

should not be required for harvest 

activities because the emissions from 

these activities (0.01 tpd) are negligible. 

ICAPCD argues that efforts to increase 

regulation of emissions from harvesting 

would waste resources. In addition, 

ICAPCD claims that the CMPs in Rule 

806 related to harvesting are similar to 

those in SJVUAPCD Rule 4550. 

Response: ICAPCD has identified 

tilling emissions as a significant 

source.154 As stated in our proposal for 

this action, measures in Rule 806 for 

harvesting must also meet BACM 

because the activities occur at the same 

facilities and are integrally related to 

tilling emissions.155 By analogy, where 

enforceable volatile organic compound 

(VOC) reasonably available control 

technology (RACT) level controls are 

required for refineries, SIP rules 

generally impose leak detection and 

repair requirements on valves, flanges, 

threaded connections and other related 

equipment even if emissions from any 

one of these taken individually might be 

much smaller than the major source 

threshold requiring RACT.156

We agree that individual CMPs for 

emissions from harvesting activities in 

Rule 806 are generally similar to CMPs 

for such emissions in the San Joaquin 

Valley. However, both SJVUAPCD and 

GBUAPCD require one more CMP for 

on-field agricultural sources than does 

Rule 806.157 This additional CMP may 

reduce emissions from harvesting 

activities. ICAPCD must establish that 

requiring fewer controls for on-field 

agricultural activities is consistent with 

BACM requirements. Thus far ICAPCD 

has not provided a convincing 

justification. 

AL #5: ICAPCD disagrees with our 

identification of the requirements of 

Rule 806 for tilling as a deficiency in the 

BACM analysis. In support of its 

position, ICAPCD asserts that San 

Joaquin Valley sources may select two 

CMPs that reduce emissions from tilling 

from the list of measures, but they are 

not required to do so. ICAPCD also 

claims that because per-acre emissions 

from land preparation are about four 

times as high in the San Joaquin Valley 

as they are in Imperial County, the costeffectiveness of emission reductions 

from tilling activities through the 

implementation of any CMP should be 

four times as high in Imperial County as 

in the San Joaquin Valley. For these two 

reasons, ICAPCD believes that Rule 806 

requirements for tilling are as stringent 

as analogous SJVUAPCD requirements. 

In contrast, Comite comments that 

Arizona Rules 18–2–610 and 611 

require at least two CMPs from each 


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39386 Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 

158 75 FR 8008, 8012. 

159Proposal TSD, pp. 10–11. 

160 Id., pp. 5–7. 

161 Id., pp. 10–11 and 17. 

category in the rule whereas Rule 806 

requires only one, and that SJVUAPCD 

requires up to three CMPs. 

Response: Although ICAPCD focuses 

here on emissions from tillage, the 

deficiency in our proposed rule is 

related to requirements in Rule 806 for 

sources to implement one fewer CMP 

overall for on-field agricultural sources 

than is required by SJVUAPCD Rule 

4550 and GBUAPCD Rule 502. Thus the 

fact that sources subject to SJVUAPCD 

Rule 4550 are not required to select two 

CMPs for reducing emissions from 

tillage is irrelevant. ICAPCD needs to 

assess whether additional CMPs for onfield agricultural sources are BACM for 

Imperial County. 

ICAPCD has not established that the 

agricultural activities in Imperial 

County are significantly different from 

those in other areas. Accordingly, EPA 

believes that ICAPCD should have 

BACM level controls for both tillage and 

harvest emissions as do other areas with 

programs for emissions from 

agricultural activities, and should 

consider SJVUAPCD and controls from 

other areas with analogous rules when 

assessing whether a requirement for 

additional CMPs would be economically 

and technologically feasible to control 

emissions from these activities. ICAPCD 

claims that implementing tillage CMPs 

may be more cost-effective in the San 

Joaquin Valley, but does not address 

whether it would be economically 

feasible to require additional CMPs in 

Imperial County. 

We agree with Comite that sources 

subject to Arizona Rules 18–2–610 and 

611 are required to implement two 

practices each from the ‘‘tillage and 

harvest’’ and ‘‘cropland’’ categories. 

ICAPCD needs to consider whether 

requiring four practices for on-field 

agricultural sources constitute BACM 

for Imperial County. 

AL #6: Comite claims that Maricopa’s 

inspection regime for agricultural 

sources is more rigorous than ICAPCD’s. 

Response: Comite provides no 

supporting information on either the 

Maricopa County or ICAPCD inspection 

program on which to base a response 

and we are not otherwise aware of 

information that supports this comment. 

AL #7: The Farm Bureau agrees that 

SJVUAPCD requires an additional CMP 

from the ‘‘cropland-other’’ category but 

notes that the same requirement is 

found in ICAPCD’s ‘‘land preparation 

and cultivation’’ and ‘‘harvest activities’’ 

categories. As a result, the Farm Bureau 

believes that including an additional 

category would be redundant and 

onerous for participants. 

Response: The deficiency identified 

in our proposed action is related to the 

requirement in Rule 806 for Imperial 

County sources to implement one fewer 

practice for on-field agricultural sources 

overall without a sufficient 

justification.158 ICAPCD does not 

necessarily need to add a category to 

Rule 806 in order to address this 

deficiency. For example, depending on 

what is most appropriate for conditions 

in Imperial County, ICAPCD may be 

able to require that more than one CMP 

be implemented from the categories that 

currently exist in Rule 806. Moreover, it 

would not be redundant to require 

Imperial County sources to implement 

an additional CMP for on-field 

agricultural sources. Rule 806 has two 

categories for on-field agricultural 

sources, ‘‘land preparation and 

cultivation’’ and ‘‘harvesting,’’ and 

requires sources to implement one 

practice from each category. As noted in 

Table 3 above, SJVUAPCD Rule 4550 

and GBUAPCD Rule 502 have three 

categories for on-field agricultural 

sources, and require that sources 

implement one practice from each of 

these categories. Moreover, as noted in 

our response to comment AL #5 above, 

sources subject to Arizona Rules 18–2– 

610 and 611 are required to implement 

four practices for on-field agricultural 

sources. As part of a BACM analysis, 

ICAPCD should consider the economic 

and technological feasibility of requiring 

additional CMPs for on-field 

agricultural sources, including 

consideration of the requirements in 

rules adopted by SJVUAPCD, GBUAPCD 

and Arizona. 

K. Agricultural Land Windblown Dust 

Controls (ALWD) 

See Introduction in section II.I above. 

ALWD #1: COLAB comments that the 

deficiencies identified by EPA related to 

windblown dust are particularly 

troublesome because they are so 

surprising. COLAB believes that Rule 

806 exceeds CAA needs because 

windblown dust from agriculture is 

insignificant. Comite, on the other hand, 

notes SCAQMD’s requirements for 

reducing windblown dust from active 

and inactive agricultural fields as BACM 

measures that ICAPCD should consider 

along with recommendations in U.S. 

Department of Agriculture’s (USDA) 

National Agronomy Manual for 

reducing such dust. 

Response: EPA has determined that 

windblown dust from agriculture is a 

significant PM10 source category in 

Imperial County for which ICAPCD 

must demonstrate, but has not yet 

demonstrated, implementation of BACM 

level controls.159 ICAPCD should 

include in its BACM analysis 

consideration of whether existing 

SCAQMD controls, among others, and 

USDA recommendations for controlling 

wind erosion, are economically and 

technologically feasible measures to 

reduce windblown dust from active and 

fallow agricultural fields. Also see 

response to comment General #3 above. 

ALWD #2: ICAPCD believes that EPA 

should have concurred with exceptional 

event requests associated with high 

winds as discussed in the exceptional 

event comments above. As a result, 

ICAPCD believes that windblown dust 

from agricultural lands is not a 

significant source category in SIP 

development, and therefore not subject 

to BACM. 

Response: In our proposed action on 

Regulation VIII, we explained how we 

determined that windblown dust from 

agricultural lands is a significant source 

category subject to BACM.160 We have 

not received information in the 

comments or elsewhere that affects this 

conclusion or the related 2009 EE 

decision. See also responses to 

exceptional event comments above and 

comment OHV #1. 

ALWD #3: ICAPCD disagrees that Rule 

806 does not apply to fallow agricultural 

fields. ICAPCD states that there are no 

exemptions in Rule 806 for fallow fields 

and fallowing is an optional CMP to 

control emissions from ‘‘land 

preparation and cultivation’’ under Rule 

806 section E.1. 

Response: Fallowing land is defined 

in Rule 806 section C.16 as ‘‘Temporary 

or permanent removal from production. 

Eliminates entire operation/passes or 

reduces activities.’’ We note that the 

fallowing CMP is an option under both 

the ‘‘land preparation and cultivation’’ 

category in section E.1 and the 

‘‘harvesting’’ category in section E.2. 

While the fallowing CMP in Rule 806 

section E.1 may reduce emissions from 

‘‘land preparation and cultivation’’ and 

from ‘‘harvesting,’’ it does not address 

any windblown dust emissions that may 

occur once a field is removed from 

production. EPA believes that the 

evaluation of BACM level controls for 

windblown dust from fallow fields 

should include consideration of USDAapproved conservation systems and 

activities.161

ALWD #4: ICAPCD comments that 

ICAPCD farms are all irrigated and 

historically well watered, which leads 

to stable clods and/or aggregates that 

lower susceptibility to wind erosion 


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162Proposal TSD, pp. 5–7. 

163 General Preamble Addendum at 42013. 

164See p. 502–17 of the USDA NRCS National 

Agronomy Manual, October 2002. 

165Proposal TSD, pp. 5–7. 

166See General Preamble Addendum at 42010 

and 42012. 

167See, e.g., 73 FR 14687, 14693 (March 19, 

2008). 

168 2009 PM10 SIP, p. 1–1. 169 2009 PM10 SIP, pp. 1–3 and 2–4. 170See, e.g., ‘‘Guidance Document for Correcting 

Common VOC and Other Rule Deficiencies,’’ U.S. 

Continued 

consistent with USDA’s National 

Agronomy Manual. ICAPCD estimates 

that long-term irrigation reduces PM10

emissions by 25–45% from the 

predominant cultivated soil types in 

Imperial County, so local fallow and 

active agricultural land is controlled for 

windblown emissions relative to land 

not previously used for irrigated 

agriculture. In contrast, ICAPCD 

believes that SCAQMD’s farm acreage is 

overwhelmingly devoted to dryland 

grain farming, and EPA has not shown 

that SCAQMD controls are appropriate 

for ICAPCD’s irrigated fields. 

Response: Based on data in Table 4, 

EPA believes that the majority of 

ICAPCD harvested acreage is irrigated. 

However, EPA disagrees that farm 

acreage subject to SCAQMD controls is 

overwhelmingly devoted to dryland 

farming. See total harvested cropland 

acres and irrigated harvested cropland 

acres for Riverside County in Table 4. 

While historic irrigation may provide 

for some level of control, windblown 

dust from agriculture is a significant 

source, and ICAPCD is required to 

implement BACM level controls for 

windblown emissions from active and 

fallow agricultural fields. ICAPCD has 

not provided a convincing justification 

for why controls in the Coachella Valley 

Planning Area are not applicable to 

Imperial sources. ICAPCD’s evaluation 

for BACM level controls for windblown 

dust from agricultural sources should 

include requirements in SCAQMD Rule 

403 and the Coachella Valley 

Agricultural Handbook. 

ALWD #5: ICAPCD notes that winds 

above 25 mph are extremely rare in the 

agricultural portion of Imperial Valley, 

and farmers usually avoid tilling on 

windy days to conserve soil. As a result, 

ICAPCD does not believe that 

SCAQMD’s restriction for soil 

preparation and maintenance during 

days with winds above 25 mph would 

impact windblown dust emissions from 

agricultural fields in Imperial County. In 

contrast, Comite points to SCAQMD’s 

requirements as potential BACM that 

ICAPCD has not properly considered. 

Response: ICAPCD must analyze and 

implement BACM for agricultural 

windblown dust emissions.162 Such 

analysis may consider whether a 

restriction on tilling activities on days 

with winds above 25 mph is appropriate 

in Imperial County pursuant to our 

guidance.163 However, ICAPCD has not 

provided such analysis in the 

Regulation VIII submittal, its comments 

or elsewhere. To the extent that farmers 

avoid tilling on windy days to conserve 

soil anyway, this restriction would not 

seem to be onerous. 

ALWD #6: ICAPCD comments that 

SCAQMD’s only additional requirement 

for active fields besides the restriction 

on tilling on days with winds above 25 

mph is to implement one more CMP 

from a list that includes minimum 

tillage. ICAPCD believes this CMP is not 

directly effective at reducing 

windblown emissions, and hence 

ICAPCD believes that by EPA’s own 

reasoning, this requirement does not 

require windblown control on active 

fields in the South Coast Basin. 

Response: ICAPCD has not explained 

why minimum tillage would not 

directly reduce windblown dust from 

active fields. EPA expects that 

minimum tillage would reduce 

windblown emissions by maintaining 

more plant residue on the field than 

conventional tillage. Establishing and 

maintaining land cover is one of the five 

principles noted in the National 

Agronomy Manual for wind erosion 

control.164

ALWD #7: Comite believes that more 

specificity and information must be 

provided concerning IID’s Fallowing 

Program to ensure that emission 

reductions from it are quantifiable, 

verifiable and enforceable. 

Response: ICAPCD must analyze and 

implement BACM for agricultural 

windblown dust emissions.165 If, as a 

result of this analysis, ICAPCD 

concludes that IID’s Fallowing Program 

is needed to implement BACM, then we 

agree that ICAPCD needs to provide 

more information about IID’s program 

and ensure that controls that are 

provided through the program are 

enforceable. 

ALWD #8: Regarding EPA concerns 

with agricultural windblown dust 

controls, ICAPCD and the Farm Bureau 

note that Rule 806 was modeled after 

EPA-approved SJVUAPCD Rule 4550 at 

EPA’s recommendation. 

Response: EPA’s guidance provides 

that BACM is determined on a case-bycase basis and can consider the specific 

conditions of the nonattainment area.166

When we approved SJVUAPCD Rule 

4550, we did not believe that 

SJVUAPCD had a regular and repeated 

windblown dust problem.167 However, 

ICAPCD asserts in its 2009 PM10 Plan 

that the ‘‘overwhelming majority of 

airborne PM in Imperial County is 

primary PM. The major source of 

primary PM is fugitive windblown dust 

* * *.’’ 168 Moreover, ICAPCD’s 2009 

PM10 Plan discusses how the flat terrain 

of Imperial Valley and strong 

temperature differentials produce 

moderate winds and how Imperial 

County occasionally experiences high 

winds with speeds greater than 30 mph 

in April and May. In addition, the 2009 

PM10 Plan attributes monitored 

exceedances in September and June to 

high winds.169 As a result, EPA believes 

that ICAPCD must consider windblown 

dust controls for agricultural sources. 

Also, see responses to comments 

General #3 and EE #5. 

ALWD #9: The Farm Bureau notes 

that both Rule 806 and the ‘‘Agricultural 

Air Quality Conservation Management 

Practices for Imperial Valley’’ were 

developed consistent with rules adopted 

in other areas and EPA 

recommendations. As a result, the Farm 

Bureau believes that this ensured Rule 

806 was adequate. 

Response: See response to comment 

General #3. 

L. Other Controls (OC) 

OC #1: Comite believes Regulation 

VIII should be further strengthened by 

removing director’s discretion in Rule 

802 section D.1, and removing the 

exemption in Rule 802 section D.4. 

ICAPCD objects to EPA’s concerns 

regarding Rule 802 section D.1 because: 

(1) The APCO’s discretion is limited to 

a determination of whether any of the 

controls in sections F.1 through F.3 can 

be implemented to satisfy the 20% 

opacity and stabilized surface 

requirements; (2) where a SIP-approved 

rule provides APCO discretion, the 

APCO can exercise the discretion 

without further SIP-approval; and (3) 

EPA has final enforcement authority for 

SIP-approved rules. 

Response: EPA believes that the 

director’s discretion provisions in Rule 

802 are generally not acceptable under 

the CAA. Regarding ICAPCD’s first 

argument, Rule 802 section D.1 provides 

the APCO discretion to waive 

completely the opacity and stabilized 

surface requirements without limiting 

discretion either by a procedure that the 

APCO must use (e.g., test method X) or 

by boundaries to the discretion (e.g., up 

to 30% opacity instead of 20% opacity). 

Thus, the discretion is not ‘‘limited.’’ 

Regarding ICAPCD’s second 

argument, we note initially that EPA has 

a long history of rejecting such broad 

APCO discretion in SIP rules.170


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EPA Region IX, August 21, 2001 (the Little 

Bluebook); and ‘‘Issues Relating to VOC Regulation 

Cutpoints, Deficiencies, and Deviations,’’ U.S. EPA, 

OAQPS, May 25, 1998 (The Bluebook). 

171Proposal TSD, p. 3. 

172See 40 CFR 6.101(b). 173 75 FR 8008, 8012–8013. 

Moreover, we limit such discretion 

precisely because the APCO can 

exercise it without further SIP approval 

where a SIP-approved rule provides 

APCO discretion. 

Regarding ICAPCD’s third argument, 

while we can enforce SIP-approved 

rules, as stated, director’s discretion 

provisions undermine their 

enforceability because enforcement of 

the rules are constrained by their terms. 

In this case, EPA or others could be 

restricted in enforcing against activity 

exempted by the APCO if this provision 

were SIP-approved. 

While we share Comite’s concerns 

with Rule 802 section D, our limited 

disapproval with respect to Rule 802 

section D will not trigger sanctions or a 

FIP obligation because Rule 802 does 

not address a source category identified 

as significant and thus requiring BACM 

at this time. Therefore our limited 

disapproval will not trigger sanctions 

under CAA section 179 or a FIP 

obligation under section 110(c) with 

respect to bulk materials regulated by 

Rule 802. However, should regulation of 

bulk materials be subject to the BACM 

requirement in the future or to meet 

other SIP planning requirements under 

CAA title I, part D such as reasonable 

further progress or attainment, the 

APCO discretion in Rule 802 section D.1 

or the exemptions in Rule 802 section 

D.4 could result in such consequences 

and/or affect the emission reduction 

credit for the rule. 

M. Statutory and Executive Order 

Reviews (SEO) 

SEO #1: OWD believes that EPA 

should address Executive Order 12898, 

which requires Federal agencies to 

identify and address disproportionately 

adverse health or environmental 

impacts on minority and low-income 

populations. Specifically, OWD believes 

that EPA’s action may impact Imperial 

County’s Hispanic and low-income 

population by reducing tourist income 

from OHV users. In contrast, Comite 

applauds the commitment of the 

Regional Administrator of EPA Region 9 

to environmental justice principles, and 

notes that relatively large portions of the 

population in this area are not only 

Hispanic and poor, but are also suffering 

from poor health and this is exacerbated 

by air pollution problems in this area. 

Response: EPA agrees it is important 

to consider environmental justice in our 

actions and we briefly addressed 

environmental justice principles in our 

proposal TSD.171 Executive Order 

12898, ‘‘Federal Actions to Address 

Environmental Justice in Minority 

Populations and Low-Income 

Populations’’ (February 16, 1994) 

establishes Federal executive policy on 

environmental justice. Its main 

provision directs Federal agencies, to 

the greatest extent practicable and 

permitted by law, to make 

environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies and activities on minority 

populations and low-income 

populations in the United States. The 

Executive Order has informed the 

development and implementation of 

EPA’s environmental justice program 

and policies. Consistent with the 

Executive Order and the associated 

Presidential Memorandum, the 

Agency’s environmental justice policies 

promote environmental protection by 

focusing attention and Agency efforts on 

addressing the types of environmental 

harms and risks that are prevalent 

among minority, low-income and Tribal 

populations. 

This action will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority, low-income or Tribal 

populations because it increases the 

level of environmental protection for all 

affected populations without having any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority or low-income population. 

Specially, EPA’s limited approval and 

limited disapproval of Regulation VIII 

would have the affect of strengthening 

environmental requirements throughout 

ICAPCD, and would not relax 

environmental requirements in any area. 

Thus it promotes environmental justice 

by increasing the level of human health 

and environmental protection for an 

area where, as the commenters note, 

relatively large portions of the 

population are low income and/or 

minority. 

SEO #2: OWD notes that EPA’s action 

may be subject to NEPA evaluation. 

Response: EPA actions under the CAA 

are exempt from NEPA.172

SEO #3: OWD believes that EPA 

should address increased management 

costs for Imperial County’s OHV 

recreation areas and the effects on OHV 

areas outside Imperial County. As a 

result, OWD does not believe that EPA 

has a basis to claim (regarding the 

Unfunded Mandates Reform Act), that 

no additional costs result from this 

action. 

Response: As explained in our 

proposal, our action would approve and 

disapprove pre-existing requirements 

under State or local law, and impose no 

new requirements. Accordingly, no 

additional costs to State, local, or tribal 

governments, or to the private sector, 

result from this action.173

III. EPA Action 

No comments were submitted that 

change our assessment of Regulation 

VIII as described in our proposed action. 

Therefore, as authorized in sections 

110(k)(3) and 301(a) of the Act, EPA is 

finalizing a limited approval of the 

submitted rules. This action 

incorporates the submitted rules into 

the California SIP, including those 

provisions identified as deficient. As 

authorized under section 110(k)(3), EPA 

is simultaneously finalizing a limited 

disapproval of the rules. As a result, 

sanctions will be imposed in Imperial 

County unless EPA approves 

subsequent SIP revisions that correct the 

rule deficiencies within 18 months of 

the effective date of this action. These 

sanctions will be imposed under section 

179 of the Act according to 40 CFR 

52.31. In addition, EPA must 

promulgate a Federal implementation 

plan (FIP) under section 110(c) unless 

we approve subsequent SIP revisions 

that correct the rule deficiencies within 

24 months. Note that the submitted 

rules have been adopted by ICAPCD, 

and EPA’s final limited disapproval 

does not prevent the local agency from 

enforcing them. 

IV. Statutory and Executive Order 

Reviews 

A. Executive Order 12866, Regulatory 

Planning and Review 

The Office of Management and Budget 

(OMB) has exempted this regulatory 

action from Executive Order 12866, 

entitled ‘‘Regulatory Planning and 

Review.’’ 

B. Paperwork Reduction Act 

This action does not impose an 

information collection burden under the 

provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. Burden is 

defined at 5 CFR 1320.3(b). 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to conduct 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements unless the 


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agency certifies that the rule will not 

have a significant economic impact on 

a substantial number of small entities. 

Small entities include small businesses, 

small not-for-profit enterprises, and 

small governmental jurisdictions. 

This rule will not have a significant 

impact on a substantial number of small 

entities because SIP limited approvals 

and limited disapprovals under section 

110 and subchapter I, part D of the 

Clean Air Act do not create any new 

requirements but simply approve and 

disapprove requirements that the State 

is already imposing. Therefore, because 

this limited approval and limited 

disapproval action does not create any 

new requirements, I certify that this 

action will not have a significant 

economic impact on a substantial 

number of small entities. 

Moreover, due to the nature of the 

Federal-State relationship under the 

Clean Air Act, preparation of flexibility 

analysis would constitute Federal 

inquiry into the economic 

reasonableness of State action. The 

Clean Air Act forbids EPA to base its 

actions concerning SIPs on such 

grounds. Union Electric Co., v. U.S. 

EPA, 427 U.S. 246, 255–66 (1976); 42 

U.S.C. 7410(a)(2). 

D. Unfunded Mandates Reform Act 

Under sections 202 of the Unfunded 

Mandates Reform Act of 1995 

(‘‘Unfunded Mandates Act’’), signed into 

law on March 22, 1995, EPA must 

prepare a budgetary impact statement to 

accompany any proposed or final rule 

that includes a Federal mandate that 

may result in estimated costs to State, 

local, or tribal governments in the 

aggregate; or to the private sector, of 

$100 million or more. Under section 

205, EPA must select the most costeffective and least burdensome 

alternative that achieves the objectives 

of the rule and is consistent with 

statutory requirements. Section 203 

requires EPA to establish a plan for 

informing and advising any small 

governments that may be significantly 

or uniquely impacted by the rule. 

EPA has determined that the limited 

approval and limited disapproval action 

promulgated does not include a Federal 

mandate that may result in estimated 

costs of $100 million or more to either 

State, local, or tribal governments in the 

aggregate, or to the private sector. This 

Federal action approves and 

disapproves pre-existing requirements 

under State or local law, and imposes 

no new requirements. Accordingly, no 

additional costs to State, local, or tribal 

governments, or to the private sector, 

result from this action. 

E. Executive Order 13132, Federalism 

Federalism (64 FR 43255, August 10, 

1999) revokes and replaces Executive 

Orders 12612 (Federalism) and 12875 

(Enhancing the Intergovernmental 

Partnership). Executive Order 13132 

requires EPA to develop an accountable 

process to ensure ‘‘meaningful and 

timely input by State and local officials 

in the development of regulatory 

policies that have federalism 

implications.’’ ‘‘Policies that have 

federalism implications’’ is defined in 

the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’ Under 

Executive Order 13132, EPA may not 

issue a regulation that has federalism 

implications, that imposes substantial 

direct compliance costs, and that is not 

required by statute, unless the Federal 

government provides the funds 

necessary to pay the direct compliance 

costs incurred by State and local 

governments, or EPA consults with 

State and local officials early in the 

process of developing the proposed 

regulation. EPA also may not issue a 

regulation that has federalism 

implications and that preempts State 

law unless the Agency consults with 

State and local officials early in the 

process of developing the proposed 

regulation. 

This rule will not have substantial 

direct effects on the States, on the 

relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132, because it 

merely approves and disapproves State 

rules implementing a Federal standard, 

and does not alter the relationship or 

the distribution of power and 

responsibilities established in the Clean 

Air Act. Thus, the requirements of 

section 6 of the Executive Order do not 

apply to this rule. 

F. Executive Order 13175, Coordination 

With Indian Tribal Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 9, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

tribal officials in the development of 

regulatory policies that have tribal 

implications.’’ This final rule does not 

have tribal implications, as specified in 

Executive Order 13175. It will not have 

substantial direct effects on tribal 

governments, on the relationship 

between the Federal government and 

Indian tribes, or on the distribution of 

power and responsibilities between the 

Federal government and Indian tribes. 

Thus, Executive Order 13175 does not 

apply to this rule. 

G. Executive Order 13045, Protection of 

Children From Environmental Health 

Risks and Safety Risks 

EPA interprets Executive Order 13045 

(62 FR 19885, April 23, 1997) as 

applying only to those regulatory 

actions that concern health or safety 

risks, such that the analysis required 

under section 5–501 of the Executive 

Order has the potential to influence the 

regulation. This rule is not subject to 

Executive Order 13045, because it 

approves State rules implementing a 

Federal standard. 

H. Executive Order 13211, Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This rule is not subject to Executive 

Order 13211, ‘‘Actions Concerning 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use’’ (66 

FR 28355, May 22, 2001) because it is 

not a significant regulatory action under 

Executive Order 12866. 

I. National Technology Transfer and 

Advancement Act 

Section 12 of the National Technology 

Transfer and Advancement Act 

(NTTAA) of 1995 requires Federal 

agencies to evaluate existing technical 

standards when developing a new 

regulation. To comply with NTTAA, 

EPA must consider and use ‘‘voluntary 

consensus standards’’ (VCS) if available 

and applicable when developing 

programs and policies unless doing so 

would be inconsistent with applicable 

law or otherwise impractical. 

The EPA believes that VCS are 

inapplicable to this action. Today’s 

action does not require the public to 

perform activities conducive to the use 

of VCS. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898, ‘‘Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations’’ (February 16, 

1994) establishes Federal executive 

policy on environmental justice. Its 

main provision directs Federal agencies, 

to the greatest extent practicable and 

permitted by law, to make 

environmental justice part of their 


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39390 Federal Register / Vol. 75, No. 130 / Thursday, July 8, 2010 / Rules and Regulations 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies and activities on minority 

populations and low-income 

populations in the United States. The 

Executive Order has informed the 

development and implementation of 

EPA’s environmental justice program 

and policies. Consistent with the 

Executive Order and the associated 

Presidential Memorandum, the 

Agency’s environmental justice policies 

promote environmental protection by 

focusing attention and Agency efforts on 

addressing the types of environmental 

harms and risks that are prevalent 

among minority, low-income and Tribal 

populations. 

This action will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority, low-income or Tribal 

populations because it increases the 

level of environmental protection for all 

affected populations without having any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority or low-income population. 

Specially, EPA’s simultaneous limited 

approval and limited disapproval of 

Regulation VIII would have the effect of 

strengthening environmental 

requirements throughout ICAPCD, and 

would not relax environmental 

requirements in any area. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this rule and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. section 804(2). This 

rule will be effective on August 9, 2010. 

L. Petitions for Judicial Review 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by September 7, 

2010. Filing a petition for 

reconsideration by the Administrator of 

this final rule does not affect the finality 

of this rule for the purposes of judicial 

review nor does it extend the time 

within which a petition for judicial 

review may be filed, and shall not 

postpone the effectiveness of such rule 

or action. This action may not be 

challenged later in proceedings to 

enforce its requirements (see section 

307(b)(2)). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Particulate matter, Reporting and 

recordkeeping requirement. 

Dated: June 15, 2010. 

Jared Blumenfeld, 

Regional Administrator, Region IX. 

■ Part 52, chapter I, title 40 of the Code 

of Federal Regulations is amended as 

follows: 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart F—California 

■ 2. Section 52.220 is amended by 

adding paragraph (c)(345)(i)(E) to read 

as follows: 

§ 52.220 Identification of plan. 

* * * * * 

(c) * * * 

(345) * * * 

(i) * * * 

(E) Imperial County Air Pollution 

Control District. 

(1) Rule 800,‘‘General Requirements 

for Control of Fine Particulate Matter 

(PM–10),’’ adopted on October 10, 1994, 

revised on November 25, 1996 and 

revised on November 8, 2005. 

(2) Rule 801,‘‘Construction & 

Earthmoving Activities,’’ Rule 802, 

‘‘Bulk Materials,’’ Rule 803,‘‘Carry-Out & 

Track-Out,’’ Rule 804,‘‘Open Areas,’’ 

Rule 805,’’Paved & Unpaved Roads,‘‘ 

Rule 806,’’Conservation Management 

Practices,’’ adopted on November 8, 

2005. 

* * * * * 

[FR Doc. 2010–16350 Filed 7–7–10; 8:45 am] 

BILLING CODE 6560–50–P 


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