Reposted with page numbers

IN THE SUPREME COURT OF 

CALIFORNIA

SIERRA CLUB et al.,

Plaintiffs and Appellants,

v.

COUNTY OF FRESNO et al.,

Defendants and Respondents;

FRIANT RANCH, L.P.,

Real Party in Interest and Respondent.

S219783

Fifth Appellate District

F066798

Fresno County Superior Court

11CECG00726, 11CECG00706, 11CECG00709

December 24, 2018

Justice Chin authored the opinion of the court, in which Chief 

Justice Cantil-Sakauye and Justices Corrigan, Liu, Cuéllar, 

Kruger, and Robie*concurred.

 

* Associate Justice of the Court of Appeal, Third Appellate 

District, assigned by the Chief Justice pursuant to article VI, 

section 6 of the California Constitution.
SIERRA CLUB v. COUNTY OF FRESNO

S219783

Opinion of the Court by Chin, J.

We granted review to determine whether an 

Environmental Impact Report (EIR), issued as part of a master 

plan to develop a partial retirement community in Fresno, 

California, violates the California Environmental Quality Act 

(CEQA) for failing to include sufficient information on topics the 

Act requires. (Pub. Resources Code, § 21000 et seq.)1 Our task 

is to review specific challenges to the final EIR2that defendant 

County of Fresno (County) and its Board of Supervisors adopted, 

and the trial court approved. As we explain, we affirm in part 

and reverse in part the Court of Appeal’s judgment. 

FACTUAL AND PROCEDURAL BACKGROUND

The Friant Ranch project (Project) consists of real party in 

interest Friant Ranch, L.P.’s (real party) planned development 

of the Central Valley’s first master-planned “pedestrian 

friendly” community on a 942-acre site (formerly zoned 

agricultural) that sits adjacent to the unincorporated 

community of Friant in north central Fresno County, just south 

 

1 All further statutory references are to CEQA provisions as 

codified in Public Resources Code sections 21000-21177 unless 

otherwise indicated. Where applicable, the CEQA guidelines 

(Cal. Code Regs., tit. 14, §§ 15000-15387) will be noted as 

“Guidelines” throughout the text to distinguish between the 

Public Resources Code and the Code of Regulations.

2 All references to the EIR are to the final EIR unless 

otherwise indicated.
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

2

of the San Joaquin River. The County is the local governmental 

entity that acted as the lead agency for the CEQA review and 

for preparation of the Project’s EIR. 

The Project includes the Friant Ranch Specific Plan

(Specific Plan), which contemplates the construction of 

approximately 2,500 single and multi-family residential units 

that are age restricted to “active adults” age 55 and older, other 

residential units that are not age restricted, a commercial 

village center, a recreation center, trails, open space, a 

neighborhood electric vehicle network, and parks and parkways. 

The Project also includes 250,000 square feet of commercial 

space on 482 acres and the dedication of 460 acres to open space. 

An additional Friant Community Plan Update expands the 

Specific Plan area and adds policies that are consistent with the 

Specific Plan and the County’s General Plan. The Project’s 

construction is divided into five phases with an estimated 10-

year build-out.

Through its Board of Supervisors, the County received 

written comments to the draft EIR, held a public hearing, and 

prepared responses to the comments. After making the findings 

required under section 21081, subdivision (a), for each 

significant effect noted in the draft, the County issued a 

Statement of Overriding Considerations (Statement) that is 

required in CEQA approved projects to show that the Project’s 

significant environmental effects have been identified, and 

avoided or mitigated, or that unmitigated effects will be 

outweighed by the Project’s benefits. (§§ 21002, 21002.1, 21081; 

Guidelines, §§ 15091-15093.) The Statement noted: “The 

Project implements and furthers important plans and public 

policies adopted and endorsed by the County related to urban 

growth.” The Statement also observed that the County “made a 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

3

reasonable and good faith effort to eliminate or substantially 

mitigate the environmental impacts resulting from the Project 

by requiring implementation of the environmentally superior 

alternative—Project Alternative No. 3: Northeast Development 

Configuration and the Beck Property alternative wastewater 

treatment plant location—and various mitigation measures, 

goals and policies identified in the EIR, General Plan, the 

proposed Friant Community Plan Update, and the proposed 

Friant Ranch Specific Plan.” 

On February 1, 2011, the County’s Board of Supervisors 

approved Project Alternative 3, certified the EIR, and approved 

a version of the Specific Plan that prohibited the discharge of 

treated effluent into the river from the wastewater treatment 

plant. The County also adopted a Mitigation Monitoring 

Program (MMP), which noted in part that compliance with the 

mitigation measures would be “enforced through subsequent 

conditions of approval for future discretionary actions,” 

including use permits and tentative subdivision maps for the 

Specific Plan area. By petition for writ of mandamus filed in the 

trial court, plaintiffs Sierra Club, Revive the San Joaquin, and 

League of Women Voters of Fresno (collectively, plaintiffs) 

challenged the County’s certification of the EIR, alleging that it 

violated CEQA in several respects. (Code Civ. Proc., §1094.5 

[challenge to public agency’s determination based on alleged 

CEQA noncompliance requires administrative mandamus 

proceeding].) The trial court rejected plaintiffs’ challenges and 

approved the Project, noting in its judgment that in reviewing 

CEQA decisions, “it may not exercise its independent judgment 

on the evidence, but must determine only whether the act or 

decision is supported by substantial evidence.” In reviewing the 

EIR, the court agreed with County’s findings on traffic impact, 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

4

biological resources, wastewater treatment, and air quality 

impact, among other considerations. It stated that the court 

“does not pass on the correctness of any EIR’s environmental 

conclusions, but instead determines whether the EIR is 

sufficient as an informational document. All conflicts in the 

evidence and reasonable inferences must be resolved and drawn 

in favor of the agency’s decisions and findings. The reviewing 

Court does not reweigh the evidence.”

The court’s judgment also observed that regarding air 

quality impacts, the County explained why the EIR’s mitigation 

measures would reduce the Project’s greenhouse gas emissions. 

The court agreed with the County that plaintiffs did not cite to 

the record in sufficient detail to show any error. 

At the end of its judgment, the court noted that it retained 

jurisdiction to allow the County a reasonable amount of time to 

circulate a Park Impact analysis on the Project’s effect on 

adjoining parks, including Lost Lake Park and Millerton Lake. 

This analysis is not at issue here. Otherwise, the court denied 

all of plaintiffs’ claims and entered judgment in favor of real 

party.

Plaintiffs appealed the judgment before the County could 

implement the mitigation measures. They claimed in relevant 

part that the Project’s EIR failed to comply with CEQA because 

its discussion of air quality impacts was inadequate.

The Court of Appeal agreed with plaintiffs’ contentions

involving the EIR’s consideration of the Project’s air quality 

impacts on the following grounds: “(1) the EIR was inadequate 

because it failed to include an analysis that correlated the 

[P]roject’s emission of air pollutants to its impact on human 

health; (2) the mitigation measures for the [P]roject’s long-term 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

5

air quality impacts violate CEQA because they are vague, 

unenforceable and lack specific performance criteria; and (3) the 

statement that the air quality mitigation provisions will 

substantially reduce air quality impacts is unexplained and 

unsupported. These defects must be cured by the preparation of 

a revised EIR.” The Court of Appeal reversed the trial court’s 

judgment on those grounds only.

3

 

We granted real party’s petition for review on the issues 

concerning the Court of Appeal’s reversal of the trial court 

judgment upholding the air quality impact findings and 

conclusions in the EIR’s chapter 3 (discussing air quality 

impacts). The scope of our review concerns how courts should

determine the adequacy of an EIR’s discussion, including: What 

standard of review a court must apply when adjudicating a 

challenge to the adequacy of an EIR’s discussion of adverse 

environmental impacts and mitigation measures, and whether 

CEQA requires an EIR to connect a project’s air quality impacts 

to specific health consequences. We must also decide whether a 

 

3 Plaintiffs had also argued that the EIR’s discussion of 

treated effluent from the proposed wastewater treatment 

facilities was inadequate and that the EIR was inconsistent with 

land use and traffic policies in the County’s General Plan. The 

Court of Appeal concluded that the amount and location of 

wastewater use and disposal, and the hydrogeology of the site 

chosen for the wastewater treatment plant, were addressed in 

sufficient detail during the environmental review process. The 

Court of Appeal also concluded that the development plan was 

consistent with the land use element (as changed from 

agricultural to residential by amendment), and that the traffic 

policy issues had not been properly exhausted during the 

administrative process. The parties do not dispute the Court of 

Appeal’s judgment on these issues, and we do not address that 

aspect of the court’s opinion here. 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

6

lead agency impermissibly defers mitigation measures when it 

retains the discretion to substitute later adopted measures in 

place of those proposed in the EIR, and whether a lead agency 

may adopt mitigation measures that do not reduce a project’s 

significant and unavoidable impacts to a less-than-significant 

level.

We conclude as follows: When reviewing whether a 

discussion is sufficient to satisfy CEQA, a court must be 

satisfied that the EIR (1) includes sufficient detail to enable 

those who did not participate in its preparation to understand 

and to consider meaningfully the issues the proposed project 

raises (Laurel Heights Improvement Assn. v. Regents of 

University of California (1988) 47 Cal.3d 376, 405 (Laurel 

Heights I)), and (2) makes a reasonable effort to substantively

connect a project’s air quality impacts to likely health 

consequences. As explained below, the EIR in this case failed to 

do so. The EIR should be revised to relate the expected adverse 

air quality impacts to likely health consequences or explain in 

meaningful detail why it is not feasible at the time of drafting to 

provide such an analysis, so that the public may make informed 

decisions regarding the costs and benefits of the Project. 

We further conclude that a lead agency may leave open the 

possibility of employing better mitigation efforts consistent with 

improvements in technology without being deemed to have 

impermissibly deferred mitigation measures. A lead agency

may adopt mitigation measures that do not reduce the project’s 

adverse impacts to less than significant levels, so long as the 

agency can demonstrate in good faith that the measures will at 

least be partially effective at mitigating the Project’s impacts. 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

7

We therefore affirm the Court of Appeal’s judgment 

finding the EIR’s analyses of the Project’s air quality impacts 

inadequate. However, we reverse the Court of Appeal’s 

judgment that the EIR improperly deferred mitigation 

measures by proposing to substitute more effective measures if 

available in the future, and that the mitigation measures 

proposed were impermissibly vague and unlikely to reduce 

adverse health impacts to less than significant levels. 

DISCUSSION

A. Adequacy of the EIR’s discussion of health impacts of 

the Project’s long-term effects on air quality

Plaintiffs claim that the EIR was insufficient as an 

informational document because it failed to adequately explain 

how the air pollutants the Project generated would impact 

public health. To address that claim, we must first decide what 

standard of review applies to a challenge to the adequacy of an 

EIR’s discussion of a required topic. 

1. Standard of review

“The foremost principle under CEQA is that the 

Legislature intended the act ‘to be interpreted in such manner 

as to afford the fullest possible protection to the environment 

within the reasonable scope of the statutory language.’ ” (Laurel 

Heights I, supra, 47 Cal.3d at p. 390, quoting Friends of 

Mammoth v. Board of Supervisors (1972) 8 Cal.3d 247, 259.) 

“With narrow exceptions, CEQA requires an EIR whenever a 

public agency proposes to approve or to carry out a project that 

may have a significant effect on the environment. [Citations.]” 

(Laurel Heights I, supra, 47 Cal.3d at pp. 390-391; see 

Guidelines, § 15002, subd. (f).) The basic purpose of an EIR is 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

8

to “provide public agencies and the public in general with 

detailed information about the effect [that] a proposed project is 

likely to have on the environment; to list ways in which the 

significant effects of such a project might be minimized; and to 

indicate alternatives to such a project.” (§ 21061; see 

Guidelines, § 15003, subds. (b)-(e).)4 “Because the EIR must be 

certified or rejected by public officials, it is a document of 

accountability. If CEQA is scrupulously followed, the public will 

know the basis on which its responsible officials either approve 

or reject environmentally significant action, and the public, 

being duly informed, can respond accordingly to action with 

which it disagrees.” (Laurel Heights I, supra, at p. 392.) The 

EIR “protects not only the environment but also informed selfgovernment.” (Ibid.) 

The standard of review in a CEQA case, as provided in 

sections 21168.5 and 21005, is abuse of discretion. Section 

21168.5 states in part: “In any action or proceeding . . . to attack, 

review, set aside, void or annul a determination, finding, or 

decision of a public agency on the grounds of noncompliance 

with this division, the inquiry shall extend only to whether there 

was a prejudicial abuse of discretion.” (See § 21005, subd. (a)

[noncompliance with information disclosure requirements may 

“constitute a prejudicial abuse of discretion”].) Our decisions 

have thus articulated a procedural issues/factual issues 

dichotomy. “[A]n agency may abuse its discretion under CEQA 

either by failing to proceed in the manner CEQA provides or by 

reaching factual conclusions unsupported by substantial 

 

4 A “significant effect” is defined as “a substantial, or 

potentially substantial, adverse change in the environment.” 

(§ 21068.) 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

9

evidence. (§ 21168.5.) Judicial review of these two types of error 

differs significantly: While we determine de novo whether the 

agency has employed the correct procedures, ‘scrupulously 

enforc[ing] all legislatively mandated CEQA requirements’

(Citizens of Goleta Valley v. Board of Supervisors (1990) 52 

Cal.3d 553, 564 [276 Cal.Rptr. 410, 801 P.2d 1161]), we accord 

greater deference to the agency’s substantive factual 

conclusions. In reviewing for substantial evidence, the 

reviewing court ‘may not set aside an agency’s approval of an 

EIR on the ground that an opposite conclusion would have been 

equally or more reasonable,’ for, on factual questions, our task 

is ‘not to weigh conflicting evidence and determine who has the 

better argument.’ (Laurel Heights I, supra, 47 Cal.3d at p. 393.)” 

(Vineyard Area Citizens for Responsible Growth, Inc. v. City of 

Rancho Cordova (2007) 40 Cal.4th 412, 435 (Vineyard).) 

This distinction between de novo review and substantial 

evidence review has worked well in judicial review of agency 

determinations. In most cases, the question whether an agency 

has followed proper procedures will have a clear answer. Did 

the agency provide sufficient notice and opportunity to comment 

on a draft EIR? (§ 21092; Guidelines, § 15087.) Did the agency 

omit the required discussion of alternatives? (Guidelines, 

§ 15126.6.) As to these legal requirements, the agency has no 

discretion, and courts will invalidate an EIR that fails to meet 

them. In that sense, judicial review is de novo.

But the question whether an agency has followed proper 

procedures is not always so clear. This is especially so when the 

issue is whether an EIR’s discussion of environmental impacts 

is adequate, that is, whether the discussion sufficiently 

performs the function of facilitating “informed agency 

decisionmaking and informed public participation.” (California 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

10

Native Plant Society v. City of Santa Cruz (2009) 177 

Cal.App.4th 957, 988 [relying on Laurel Heights I, supra, 47 

Cal.3d at pp. 404-405].) The review of such claims does not fit 

neatly within the procedural/factual paradigm.

This court’s decision in Laurel Heights I illustrates how a 

court should assess a claim of inadequate discussion. The case 

involved a challenge to an EIR’s discussion of alternatives to the 

proposed construction of the University of California, San 

Francisco’s (UCSF) Laurel Heights campus. This court 

concluded that the discussion was inadequate: “UCSF’s 

treatment of alternatives was cursory at best. The draft EIR 

identified three types of alternatives: no project anywhere, 

alternative sites on the UCSF Parnassus campus, and 

alternative sites off-campus. The three categories received a 

scant one and one-half pages of text in an EIR of more than 250 

pages. The EIR stated the obvious conclusion that the ‘no 

project’ alternative, i.e., no relocation to Laurel Heights, would 

not have the environmental effects identified in the EIR. It then 

stated in a mere two-sentence paragraph that ‘. . . no alternative 

sites on [the Parnassus] campus were evaluated as possible 

candidates for the location of the basic science units of the 

School of Pharmacy.’ This is not a sufficient discussion of oncampus alternatives; it is merely an admission that such 

alternatives were not considered.” (Laurel Heights I, supra, 47 

Cal.3d at p. 403.)

Laurel Heights I continued: “Even if the Regents are 

correct in their conclusion that there are no feasible alternatives 

to the Laurel Heights site, the EIR is nonetheless defective 

under CEQA. As we stated in a context similar to CEQA, there 

must be a disclosure of the ‘analytic route the . . . agency 

traveled from evidence to action.’ (Topanga Assn. for a Scenic 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

11

Community v. County of Los Angeles (1974) 11 Cal.3d 506, 515 

[construing requirements of Gov. Code, § 65906 for zoning 

variances]; [citation].) The EIR prepared by UCSF contains no 

analysis of any alternative locations. An EIR’s discussion of 

alternatives must contain analysis sufficient to allow informed 

decision making. (San Bernardino Valley Audubon Society, Inc.

v. County of San Bernardino (1984) 155 Cal.App.3d 738, 751

[202 Cal.Rptr. 423].)” (Laurel Heights I, supra, 47 Cal.3d at 

p. 404.)

In Laurel Heights I this court was clear that its inquiry 

was not a matter of reviewing the record for substantial 

evidence: “The Regents also contend the [project opponents] 

failed to point to any evidence in the record that demonstrates 

reasonable alternatives to moving the School of Pharmacy 

research units to Laurel Heights. This argument is somewhat 

disingenuous given the Regents’ own failure to provide any 

meaningful information regarding alternatives. It is the project 

proponent’s responsibility to provide an adequate discussion of 

alternatives. (Guidelines, § 15126, subd. (d).) That 

responsibility is not dependent in the first instance on a showing 

by the public that there are feasible alternatives. If the project 

proponent concludes there are no feasible alternatives, it must 

explain in meaningful detail in the EIR the basis for that 

conclusion.” (Laurel Heights I, supra, 47 Cal.3d at p. 405.)

Recently, in Cleveland National Forest Foundation v. San 

Diego Assn. of Governments (2017) 3 Cal.5th 497, 514–515

(Cleveland National Forest), this court made a similar point that 

the adequacy of an EIR’s discussion of environmental impacts is 

an issue distinct from the extent to which the agency is correct 

in its determination whether the impacts are significant. “[A]n 

EIR’s designation of a particular adverse environmental effect 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

12

as ‘significant’ does not excuse the EIR’s failure to reasonably 

describe the nature and magnitude of the adverse effect. (See 

Berkeley Keep Jets Over the Bay Com. v. Board of Port Cmrs.

(2001) 91 Cal.App.4th 1344, 1371 [111 Cal.Rptr.2d 598] [‘The 

EIR’s approach of simply labeling the effect “significant”

without accompanying analysis of the project’s impact on the 

health of the Airport’s employees and nearby residents is 

inadequate to meet the environmental assessment 

requirements of CEQA.’]; Galante Vineyards v. Monterey 

Peninsula Water Management Dist. (1997) 60 Cal.App.4th 1109, 

1123 [71 Cal.Rptr.2d 1].) An adequate description of adverse 

environmental effects is necessary to inform the critical 

discussion of mitigation measures and project alternatives at 

the core of the EIR. (See Guidelines, § 15151 [‘An EIR should 

be prepared with a sufficient degree of analysis to provide 

decisionmakers with information which enables them to make a 

decision which intelligently takes account of environmental 

consequences.’].)” (Ibid.)

However, there are instances where the agency’s 

discussion of significant project impacts may implicate a factual 

question that makes substantial evidence review appropriate. 

For example, a decision to use a particular methodology and 

reject another is amenable to substantial evidence review, as 

Sierra Club concedes. But whether a description of an 

environmental impact is insufficient because it lacks analysis or 

omits the magnitude of the impact is not a substantial evidence 

question. A conclusory discussion of an environmental impact 

that an EIR deems significant can be determined by a court to 

be inadequate as an informational document without reference 

to substantial evidence.
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

13

Our Courts of Appeal have consistently recognized that 

adequacy of discussion claims are not typically amenable to 

substantial evidence review. As the court explained in County 

of Amador v. El Dorado County Water Agency (1999) 76 

Cal.App.4th 931, 945-946, “Substantial evidence challenges are 

resolved much as substantial evidence claims in any other 

setting: a reviewing court will resolve reasonable doubts in 

favor of the administrative decision, and will not set aside an 

agency’s determination on the ground that the opposite 

conclusion would have been equally or more reasonable. 

[Citations.] [¶] A claim that an agency failed to act in a manner 

required by law presents other considerations. Noncompliance 

with substantive requirements of CEQA or noncompliance with 

information disclosure provisions ‘which precludes relevant 

information from being presented to the public agency . . . may 

constitute prejudicial abuse of discretion within the meaning of 

Sections 21168 and 21168.5, regardless of whether a different 

outcome would have resulted if the public agency had complied 

with those provisions.’ (§ 21005, subd. (a).) . . . [W]hen an 

agency fails to proceed [as CEQA requires], harmless error 

analysis is inapplicable. The failure to comply with the law 

subverts the purposes of CEQA if it omits material necessary to 

informed decisionmaking and informed public participation. 

Case law is clear that, in such cases, the error is prejudicial. 

(Sierra Club v. State Bd. of Forestry (1994) 7 Cal.4th 1215, 1236-

1237 [32 Cal.Rptr.2d 19, 876 P.2d 505]; Fall River Wild Trout 

Foundation v. County of Shasta (1999) 70 Cal.App.4th 482, 491-

493 [82 Cal.Rptr.2d 705]; Kings County Farm Bureau v. City of 

Hanford (1990) 221 Cal.App.3d 692, 712 [270 Cal.Rptr. 650]; 

East Peninsula Ed. Council, Inc. v. Palos Verdes Peninsula 

Unified School Dist. (1989) 210 Cal.App.3d 155, 174 [258 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

14

Cal.Rptr. 147] (East Peninsula); Rural Landowners Assn. v. City 

Council (1983) 143 Cal.App.3d 1013, 1021–1023 [192 Cal.Rptr. 

325].)” (Italics added.) The court in that case concluded that 

the EIR was insufficient because among other things it failed to 

adequately describe environmental baseline conditions. 

(County of Amador, at pp. 952–956.)

We also affirm that in reviewing an EIR’s discussion, we 

do not require technical perfection or scientific certainty: 

“ ‘ “[T]he courts have looked not for an exhaustive analysis but 

for adequacy, completeness and a good-faith effort at full 

disclosure.” ’ ” (California Native Plant Society v. City of Santa 

Cruz, supra, 177 Cal.App.4th at p. 979; accord Laurel Heights I,

supra, 47 Cal.3d at p. 406; see Guidelines, § 15151 [“An 

evaluation of the environmental effects of a proposed project 

need not be exhaustive, but the sufficiency of an EIR is to be 

reviewed in the light of what is reasonably feasible.”].) 

Three basic principles emerge from our decisions and 

those of the Court of Appeal: (1) An agency has considerable 

discretion to decide the manner of the discussion of potentially 

significant effects in an EIR. (2) However, a reviewing court 

must determine whether the discussion of a potentially

significant effect is sufficient or insufficient, i.e., whether the 

EIR comports with its intended function of including “ ‘ “detail 

sufficient to enable those who did not participate in its 

preparation to understand and to consider meaningfully the 

issues raised by the proposed project.” ’ ” (Bakersfield Citizens 

for Local Control v. City of Bakersfield (2004) 124 Cal.App.4th 

1184, 1197 (Bakersfield).) (3) The determination whether a 

discussion is sufficient is not solely a matter of discerning 

whether there is substantial evidence to support the agency’s 

factual conclusions.
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Opinion of the Court by Chin, J.

15

The ultimate inquiry, as case law and the CEQA 

guidelines make clear, is whether the EIR includes enough 

detail “to enable those who did not participate in its preparation 

to understand and to consider meaningfully the issues raised by 

the proposed project.” (Laurel Heights I, supra, 47 Cal.3d at 

p. 405; see Berkeley Keep Jets Over the Bay Com. v. Board of Port 

Cmrs., supra, 91 Cal.App.4th at p. 1356 [“Whether an EIR will 

be found in compliance with CEQA involves an evaluation of 

whether the discussion of environmental impacts reasonably 

sets forth sufficient information to foster informed public 

participation and to enable the decision makers to consider the 

environmental factors necessary to make a reasoned decision.”]; 

Guidelines, § 15151 [“An EIR should be prepared with a 

sufficient degree of analysis to provide decisionmakers with 

information which enables them to make a decision which 

intelligently takes account of environmental consequences.”].) 

The inquiry presents a mixed question of law and fact. As such, 

it is generally subject to independent review. However, 

underlying factual determinations—including, for example, an 

agency’s decision as to which methodologies to employ for 

analyzing an environmental effect—may warrant deference. 

(Cf. Mountain Air Enterprises, LLC v. Sundowner Towers, LLC

(2017) 3 Cal.5th 744, 751; Crocker National Bank v. City and 

County of San Francisco (1989) 49 Cal.3d 881, 888.) Thus, to 

the extent a mixed question requires a determination whether 

statutory criteria were satisfied, de novo review is appropriate; 

but to the extent factual questions predominate, a more 

deferential standard is warranted. (Connerly v. State Personnel 

Bd. (2006) 37 Cal.4th 1169,1175.) 

Real party draws a distinction for standard of review 

purposes between claims that a required discussion has been 
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Opinion of the Court by Chin, J.

16

omitted altogether and claims that a required discussion is 

insufficient, with the former subject to de novo review and the 

latter subject to substantial evidence review. But such a 

distinction is neither consistent with our precedent (see Laurel 

Heights I, supra, 47 Cal.3d at pp. 403–405) nor logically 

defensible. Whether or not the alleged inadequacy is the 

complete omission of a required discussion or a patently 

inadequate one-paragraph discussion devoid of analysis, the 

reviewing court must decide whether the EIR serves its purpose 

as an informational document. 

2. The EIR’s air quality discussion

The Court of Appeal’s opinion presents a concise summary 

of the EIR’s discussion regarding the Project’s air quality 

impacts on public health.

“The EIR’s discussion of Impact No.3.3.2, the long-term 

area and operational emissions, estimated that, at build-out, the 

proposed Friant Community Plan would emit approximately 

117.38 tons per year of PM10 [particulate matter 10 microns in 

diameter or smaller], 109.52 tons per year of reactive organic 

gases (ROG), and 102.19 tons per year of nitrogen oxides (NOx). 

Estimates were made for ROG and NOx because they are 

precursors to ozone, which is formed when ROG and NOx 

undergo chemical reactions in the presence of sunlight.

“The Air District’s thresholds of significance are 15, 10 and 

10 tons per year for PM10, ROG and NOx, respectively. Because 

the project’s estimated emission of PM10, ROG and NOx were 

from seven to 10 times larger than that of the thresholds of 

significance, the EIR concluded these air pollutants would have 

a significant adverse effect on air quality. Because Mitigation 

Measure 3.3.2 could not reduce these emissions below the Air 
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Opinion of the Court by Chin, J.

17

District’s thresholds of significance, the EIR concluded that the 

significant impacts were unavoidable.

“The draft EIR included a page of background information 

about ozone and nearly a page of background information about 

PM10. Each included a paragraph about the adverse health 

effects associated with the pollutant. The discussion of the 

adverse health effects, however, was not connected to the levels 

of the pollutant that would be emitted by the completed project. 

Instead, the discussion of adverse health effects was general in 

nature. For example, the description of the health effects of 

ozone noted that the effects were primarily to the respiratory 

system and stated:

‘Exposure to ambient levels of ozone ranging from 0.10 to 

0.40 [parts per million] for 1 to 2 hours has been found to 

significantly alter lung functions by increasing respiratory rates 

and pulmonary resistance, decreasing tidal volumes, and 

impairing respiratory mechanics.’ 

“As to PM10, the EIR stated its adverse health effects 

depended upon ‘the specific composition of the particulate 

matter.’ The EIR, however, provided no information about the 

composition of the particulate matter that was expected to be 

produced by the Project.” 

3. Adequacy of the EIR’s discussion of public health 

impacts from air pollutants that the Project is 

expected to generate

Real party contends that the EIR satisfied all CEQA 

requirements because it analyzed the Project’s air quality 

impacts and disclosed the Project’s likely general health 

impacts. Plaintiffs argue that the EIR failed to satisfy 

Guidelines section 15126.2, subdivision (a), which requires an 
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Opinion of the Court by Chin, J.

18

EIR to “analyze any significant environmental effects the project 

might cause by bringing development and people into the area 

affected.” In other words, they argue, the Project’s health effects 

must be “clearly identified” and the discussion must include 

“relevant specifics” about the environmental changes 

attributable to the Project and their associated health outcomes. 

The Court of Appeal held that the EIR’s analysis of air 

quality impacts was inadequate because it did not connect the 

raw particulate numbers and their effect on air quality with 

specific adverse effects on human health in the built 

environment. (See Bakersfield, supra, 124 Cal.App.4th at p.

1193.) Bakersfield considered EIRs relating to the construction 

and operation of two shopping centers in the City of Bakersfield. 

(Ibid.) The shopping centers featured a Wal-Mart Supercenter 

as their primary tenant and anchor. (Id. at p. 1194.) Both EIRs 

concluded that the projects would have “significant and 

unavoidable adverse impacts on air quality.” (Id. at p. 1219.) 

But neither EIR specifically identified the health impacts that 

would result from the adverse air quality effects. The appellate 

court criticized the EIRs because they lacked an 

“acknowledgement or analysis of the well-known connection 

between reduction in air quality and increases in specific 

respiratory conditions and illnesses. After reading the EIRs, the 

public would have no idea of the health consequences that result 

when more pollutants are added to a nonattainment basin.” (Id.

at p. 1220.) Bakersfield concluded that brief references to 

adverse health impacts on human respiratory health rendered 

the EIRs in that case inadequate as a matter of law because they 

failed to connect the adverse air impact with negative health 

effects. (Ibid.) The court held that “the health impacts resulting 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

19

from the adverse air quality impacts must be identified and 

analyzed in the new EIRs.” (Ibid., italics added.) 

The Court of Appeal acknowledged that the EIR at issue 

here went “much further than” the Bakersfield EIRs, noting that 

the EIR not only listed the type and tons per year of the 

pollutants the Project is expected to produce, but also provided

a general description of each pollutant and how it affects human 

health. The Court of Appeal found, however, that the EIR was 

inadequate under CEQA because its analysis failed to correlate 

the increase in emissions that the Project would generate to the 

adverse impacts on human health.

Real party had argued below that “the reader can infer 

from the provided information that the Project will make air 

quality and human health worse.” But the Court of Appeal 

concluded that “although the better/worse dichotomy is a useful 

starting point for analyzing adverse environmental impacts, 

including those to human health, more information is needed to 

understand that adverse impact.”

The EIR does include some discussion of the health 

impacts of various pollutants and attempts to provide an 

explanation for its lack of specificity. It offers a general 

discussion of adverse health effects associated with certain 

Project-related pollutants. Notably, it also recognized that 

Fresno County suffers from the “most severe” ozone problems in 

the state and acknowledged the relationship between adverse 

ambient air quality and certain health risks to the respiratory 

system that could affect asthmatics, children, and healthy 

adults. These adverse effects, the draft EIR observed, could 

include “breathing and respiratory symptoms, aggravation of 

existing respiratory and cardiovascular diseases, alterations to 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

20

the immune system, carcinogenesis, and premature death.” The 

EIR explained, however, that a more detailed analysis of health 

impacts is not possible at this early planning phase. According 

to the EIR, “Health Risk Assessments are typically prepared for 

inclusion in development specific project EIRs when certain 

types of development commonly known to have the potential to 

result in a human health risk are being proposed (automobile 

fueling stations [for example]). Due to the broad nature of the 

planning approvals analyzed in this EIR, it is impossible to 

conduct a human health risk assessment based on specific 

proposed uses at specific locations within the boundaries of the 

Project Area because such specific information has not been 

determined.”

We agree with the Court of Appeal that the EIR’s 

discussion of health impacts found in Impact No. 3.3.2 is 

inadequate as an informational document, similar to what the 

court found in Bakersfield, supra, 124 Cal.App.4th at p. 1220. 

The EIR’s discussion of health impacts of the named pollutants 

provides only a general description of symptoms that are 

associated with exposure to the ozone, particulate matter (PM), 

carbon monoxide (CO), and nitrogen dioxide (NOx), and the 

discussion of health impacts regarding each type of pollutant is 

at most a few sentences of general information. The disclosures 

of the health effects related to PM, CO, and sulfur dioxide fail to 

indicate the concentrations at which such pollutants would 

trigger the identified symptoms. As in Bakersfield, “[a]fter 

reading the EIRs, the public would have no idea of the health 

consequences that result when more pollutants are added to a 

nonattainment basin.” (Bakersfield, supra, 124 Cal.App.4th at 

p. 1220.) And as mentioned above, a sufficient discussion of 

significant impacts requires not merely a determination of 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

21

whether an impact is significant, but some effort to explain the 

nature and magnitude of the impact. (See Cleveland National 

Forest, supra, 3 Cal.5th at pp. 514–515.) The EIR in this case 

fails to meet the standards articulated in Bakersfield and 

Cleveland National Forest. 

Even in the one area in which the EIR goes into some 

detail about health effects––ozone––the analysis is inadequate. 

The EIR states: “Exposure to ambient levels of ozone ranging 

from 0.10 to 0.40 [parts per million of ozone] has been found to 

significantly alter lung functions by increasing respiratory rates 

and pulmonary resistance, decreasing tidal volumes, and 

impairing respiratory mechanics. Ambient levels of ozone above 

0.12 [parts per million] are linked to symptomatic responses 

that include such symptoms as throat dryness, chest tightness, 

headache, and nausea.” 

At first glance, this information appears to potentially 

illuminate the health impacts of ozone produced by the Project. 

But the EIR presents no evidence of the anticipated parts per 

million (ppm) of ozone as a result of the Project. Rather, the EIR 

provides the estimated tons per year of reactive organic material 

(ROG) and NOx, the two components that react with sunlight to 

form ozone (i.e., ROG + NOx + sunlight → ozone). The raw 

numbers estimating the tons per year of ROG and NOx from the 

Project do not give any information to the reader about how 

much ozone is estimated to be produced as a result. Therefore, 

the disclosure of the health impacts associated with exposure to 

0.10 to 0.40 ppm of ozone is not meaningful within the context 

of the Project because the reader has no idea how much ozone 

will be produced (i.e., whether the amount of ozone resulting 

from the ROG and NOx pollution will bring the ozone ppm 

within the 0.10 to 0.40 range).
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

22

Guidelines section 15126.2, subdivision (a) is instructive. 

It mandates that an EIR “identify and focus on the significant 

environmental effects of the proposed project . . . examin[ing] [] 

changes in the existing physical conditions in the affected area,” 

that it identify and describe “[d]irect and indirect significant 

effects of the project on the environment,” and that the 

discussion should include, among other things, “relevant 

specifics of . . . health and safety problems caused by the 

physical changes.” It also suggests that a connection be drawn 

between the two segments of information presented in the 

EIR—potential project emissions and human health impacts. 

Such a connection would meet CEQA’s requirements. 

Relying on various amici curiae briefs submitted to the 

court, the County and real party attempt to explain why the 

connection between emissions and human health that plaintiffs 

seek cannot be provided given the state of environmental science 

modeling in use at this time. The parties may be correct; we 

express no view on the question, except to note that scientific 

certainty is not the standard. But if it is not scientifically 

possible to do more than has already been done to connect air 

quality effects with potential human health impacts, the EIR 

itself must explain why, in a manner reasonably calculated to 

inform the public of the scope of what is and is not yet known

about the Project’s impacts. Contained in a brief, such 

explanation is directed at the wrong audience. The relevant 

informational document here is the EIR, and the EIR must 

communicate not to the reviewing court, but “the public and the 

government officials deciding on the project.” (Vineyard, supra, 

40 Cal.4th at p. 443.) For purposes of supplementing the EIR 

and bringing it in conformance with CEQA, the information 

contained in the briefs “is irrelevant [] because the public and 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

23

decision makers did not have the briefs available at the time the 

project was reviewed and approved.” (Ibid. [“That a party’s 

briefs to the court may explain or supplement matters that are 

obscure or incomplete in the EIR [] is irrelevant . . . . The 

question is [] not whether the project’s significant 

environmental effects can be clearly explained, but whether 

they were.”].) 

We further reject real party’s argument that the EIR 

sufficiently accounted for its lack of specificity by explaining 

that a “Health Risk Assessment” is typically prepared later in 

the CEQA process, in connection with development-specific 

EIRs. A “Health Risk Assessment” is defined in the Health and 

Safety Code as a type of analysis undertaken in connection with 

the siting of hazardous substances, “a detailed comprehensive 

analysis . . . to evaluate and predict the dispersion of hazardous 

substances in the environment and the potential for exposure of 

human populations and to assess and quantify both the 

individual and population wide health risks associated with 

those levels of exposure.” (Health & Saf. Code, § 44306.)

CEQA does not mandate such an in-depth risk 

assessment. CEQA requires that the EIR have made a 

reasonable effort to discuss relevant specifics regarding the 

connection between two segments of information already 

contained in the EIR, the general health effects associated with 

a particular pollutant and the estimated amount of that 

pollutant the project will likely produce. This discussion will 

allow the public to make an informed decision, as CEQA 

requires. Because the EIR as written makes it impossible for 

the public to translate the bare numbers provided into adverse 

health impacts or to understand why such translation is not 

possible at this time (and what limited translation is, in fact, 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

24

possible), we agree with the Court of Appeal that the EIR’s 

discussion of air quality impacts in this case was inadequate.

The Court of Appeal identified several ways in which the 

EIR could have framed the analysis so as to adequately inform 

the public and decision makers of possible adverse health 

effects. The County could have, for example, identified the 

Project’s impact on the days of nonattainment per year. But the 

Court of Appeal was clear that, ultimately—though the EIR 

must provide an analysis that is adequate to inform (Guidelines, 

§ 15151)—the “County has discretion in choosing what type of 

analysis to provide . . . .” We agree. The task for real party and 

the County is clear: The EIR must provide an adequate analysis 

to inform the public how its bare numbers translate to create 

potential adverse impacts or it must adequately explain what 

the agency does know and why, given existing scientific 

constraints, it cannot translate potential health impacts further. 

To be sure, “ ‘courts have looked not for perfection but for 

adequacy, completeness, and a good faith effort at full 

disclosure.’ ” (In re Bay-Delta etc. (2008) 43 Cal.4th 1143, 1175.) 

But basic CEQA principles dictate there must be a reasonable 

effort to put into a meaningful context the conclusion that the 

air quality impacts will be significant. Although the EIR 

generally outlines some of the unhealthy symptoms associated 

with exposure to various pollutants, it does not give any sense 

of the nature and magnitude of the “health and safety problems 

caused by the physical changes” resulting from the Project as 

required by the CEQA guidelines. (Guidelines, § 15126.2, subd. 

(a).) Perhaps it was not possible to do more. But even in that 

case, we would have found the EIR insufficient because it failed

to explain why it was not feasible to provide an analysis that 

connected the air quality effects to human health consequences.
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

25

B. Mitigation measures

1. “Substantially reduce air quality impacts”

At the outset of the discussion of proposed Mitigation 

Measure 3.3.2 (discussed more fully in part D below), the EIR 

stated that “Implementation of the following mitigation 

measures will substantially reduce air quality impacts related 

to human activity within the entire Project area but not to a 

level that is less than significant.” 

The Court of Appeal concluded that the EIR’s use of the 

term “substantial” to describe the impact the proposed 

mitigation measures would have on reducing the Project’s 

significant health effects, without further explanation or factual 

support, amounted to a “bare conclusion” that did not satisfy 

CEQA’s disclosure requirements. 

We agree with the Court of Appeal on this point. (See 

Laurel Heights I, supra, 47 Cal.3d at pp. 404 - 405 [“ ‘To 

facilitate CEQA’s informational role, the EIR must contain facts 

and analysis, not just the agency’s bare conclusions or opinions.’ 

”].) Here, the EIR included no facts or analysis to support the

inference that the mitigation measures will have a quantifiable 

“substantial” impact on reducing the adverse effects. The EIR 

must accurately reflect the net health effect of proposed air 

quality mitigation measures. (Cleveland National Forest, supra, 

3 Cal.5th at p. 514 [“an EIR’s designation of a particular adverse 

environmental effect as ‘significant’ does not excuse the EIR’s 

failure to reasonably describe the nature and magnitude of the 

adverse effect”].)

2. Deferral of mitigation measures 

We next decide whether, as the Court of Appeal concluded,

the County, as the lead agency, impermissibly deferred
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

26

mitigation measures when it approved real party’s EIR, which 

included mitigation measures to “at least partially reduce” the 

Project’s air quality impacts, as well as a substitution clause for 

future mitigation methods. Plaintiffs contend that the Project’s 

EIR is insufficient, because “the mitigation analysis is devoid of 

criteria for measuring the effectiveness of mitigation measures.” 

(Guidelines, §15126.4, subd. (a)(1)(B); see Sundstrom v. County 

of Mendocino (1988) 202 Cal.App.3d 296, 306-307 [improper to 

defer formulation of mitigation measures until after project 

approved].) Plaintiffs agree with the Court of Appeal’s 

conclusion that the formulation of future substitutions in this 

case was improperly deferred. 

The general rule is that an EIR is required to provide the 

information needed to alert the public and the decision makers 

of the significant problems a project would create and to discuss 

currently feasible mitigation measures. Mitigation measures 

need not include precise quantitative performance standards, 

but they must be at least partially effective, even if they cannot 

mitigate significant impacts to less than significant levels. 

(Laurel Heights I, supra, 47 Cal.3d at p. 404; §§ 21051, 21100; 

Guidelines, § 15370.)5

 

5 Guidelines section 15370 provides that legally adequate 

mitigation measures must be capable of “(a) Avoiding the impact 

altogether by not taking a certain action or parts of an action. 

[¶] (b) Minimizing impacts by limiting the degree or magnitude 

of the action and its implementation. [¶] (c) Rectifying the 

impact by repairing, rehabilitating, or restoring the impacted 

environment. [¶] (d) Reducing or eliminating the impact over 

time by preservation and maintenance operations during the life 

of the action. [¶] (e) Compensating for the impact by replacing 

or providing substitute resources or environments.”
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

27

In the present matter, the Project’s EIR noted that the air 

quality impacts will be significant and unavoidable. But the 

EIR’s 12 mitigation measures in Mitigation Measure 3.3.2 were

designed to reduce the Project’s air quality impacts by providing 

shade trees, utilizing efficient PremAir or similar model

heating, ventilation, and air conditioning [HVAC] systems, 

building bike lockers and racks, creating bicycle storage spaces 

in units, and developing transportation related mitigation that 

will include trail maps and commute alternatives. 

Mitigation Measure 3.3.2 includes a substitution clause 

that allows the lead agency to “substitute different air pollution 

control measures for individual projects, that are equally 

effective or superior to those propose[d] [in the EIR], as new 

technology and/or other feasible measures become available 

[during] build-out within the [Project].” In other words, the 

County retains the discretion to modify or substitute the 

adopted mitigation with equally or more effective measures in 

the future as better technology becomes available, unless the 

changes increase a project’s significant impacts. (See 

Guidelines, § 15162, subd. (a)(3).)

The County concluded that the Project’s air quality 

impacts will be significant, and that the 12 mitigation measures 

set forth in the Specific Plan should be at least partially effective 

in reducing the significant impacts. The substitution clause will 

allow for additional and presumably better mitigation measures 

when they become available and it should be encouraged. (See 

Napa Citizens for Honest Government v. Napa County Bd. of 

Supervisors (2001) 91 Cal.App.4th 342, 357−358 [recognizing 

county must have power to modify land use plans].) Allowing 

future substitutions for equal or more efficient technology to 

mitigate a project’s acknowledged significant effects promotes 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

28

CEQA’s goal of environmental protection and is not an 

impermissible deferral of mitigation or an abuse of discretion. 

It is simply a recognition that substitutions of adopted 

mitigation measures may be implemented to further minimize 

the Project’s environmental impacts. 

3. Failure to reduce impacts to less than significant 

levels

Plaintiffs also ask us to decide whether a lead agency 

violates CEQA when its proposed mitigation measures will not

reduce a significant environmental impact to less than

significant levels. We conclude that as long as the public is able 

to identify any adverse health impacts clearly, and the EIR’s

discussion of those impacts includes relevant specifics about the 

environmental changes attributable to the project, the inclusion 

of mitigation measures that partially reduce significant impacts 

does not violate CEQA.

We have stated that protection of the environment and of 

California’s resources has long been considered of the utmost 

importance. However, in enacting CEQA to protect the 

environment, the Legislature did not seek to prevent all 

development. Section 21081, subdivision (b) allows a project to 

continue even if there are significant environmental effects that 

have not been mitigated, if “the public agency finds that specific 

overriding economic, legal, social, technological, or other 

benefits of the project outweigh the significant effects on the 

environment.”

If, after the feasible mitigation measures have been 

implemented, significant effects still exist, a project may still be 

approved if it is found that the “unmitigated effects are 

outweighed by the project’s benefits.” (Laurel Heights I, supra, 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

29

47 Cal.3d at p. 391.) Even when a project’s benefits outweigh its 

unmitigated effects, agencies are still required to implement all 

mitigation measures unless those measures are truly infeasible. 

(City of San Diego v. Board of Trustees of California State 

University (2015) 61 Cal.4th 945, 967.) We recently held that 

“the lead agency must adopt feasible mitigation measures or 

project alternatives to reduce the effect to insignificance; to the 

extent significant impacts remain after mitigation, the agency 

may still approve the project with a statement of overriding 

considerations. [Citations.]” (Center for Biological Diversity v.

Department of Fish & Wildlife (2015) 62 Cal.4th 204, 231.) The 

inclusion of a mitigation measure that reduces an 

environmental impact is permitted even if the measure will not 

reduce the impact to a level below the threshold of significance.

4. Enforceability of mitigation measures 

Plaintiffs argue that mitigation measures involving the 

installation of HVAC systems and tree planting, and any 

required mitigation efforts that “are fully enforceable through 

permit conditions, agreement, or other measures,” are 

unenforceable. (§ 21081.6, subd. (b).) We note that the 

measures referred to in this section are proposed as “guidelines”

that “shall be used by the County during review of future 

project-specific submittals for non-residential development . . . 

with [the] intent that specified measures be required where 

feasible and appropriate.”

The Court of Appeal found the EIR mitigation “provision 

about equipping HVAC units with a catalyst system does not 

identify who will determine if the system is ‘reasonably 

available and economically feasible’ ” and is unenforceable. In 

its analysis, the court omitted the next sentence, “[c]atalyst 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

30

systems are considered feasible if the additional cost is less than 

10% of the base HVAC cost.” This definition of what constitutes 

“economically feasible” catalyst systems eliminates the need to 

have individuals make such determinations. The Court of 

Appeal also found the phrase “ ‘PremAir or similar catalyst 

system’ ” vague for not defining what performance criteria must 

be met to be a “ ‘similar catalyst system.’ ” The term is not 

vague. PremAir is a brand name for an HVAC catalyst system. 

The individuals proposing new projects, or those tasked with 

evaluating the proposals for approval, would necessarily have 

knowledge of HVAC systems and catalyst systems, including

PremAir. It is also impossible to require specific performance 

criteria, given that the type, size, model, and efficiency levels of 

the HVAC systems being installed in these future projects are 

unknown. Given the uncertainty of these future proposed 

projects, the language “ ‘PremAir or similar catalyst system’ ” is 

sufficient under CEQA to provide an enforceable mitigation 

measure for any HVAC systems associated with those projects. 

The Court of Appeal similarly found that the mitigation 

measure requiring trees be selected to provide shade did not 

specify the person(s) responsible for selecting which trees to 

plant. The measure instructs that “ ‘[t]rees selected to shade 

paved areas should be varieties that will shade 25% of the paved 

area within 20 years.’ ” The instruction provides sufficient 

guidance for selecting appropriate shade trees. Any plan that 

the County approves must be complete, and must contain 

information about the trees selected for this mitigation 

measure. It seems clear that the person(s) selecting the trees 

would be the individuals or entity submitting the plans to the 

County for approval. The measure is not vague.
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

31

In finding the mitigation measures cannot be enforced 

through permit conditions, agreements, or other measures, the 

Court of Appeal also misinterpreted section 21081.6, subdivision 

(b) and its significant effects provision, which provides that a 

public agency may set forth conditions of project approval 

required to avoid significant effects in “referenced documents 

which address [or incorporate the] required mitigation 

measures . . . into the plan.” (§ 21081.6, subd. (b).) The Project’s 

MMP places the burden of enforcement on the County to “ensure 

that all construction plans and project operations conform to the 

conditions of the mitigated project.” The Specific Plan 

additionally states that “The County shall monitor compliance 

with the Specific Plan and mitigation measures,” and it provides 

the stages of planning at which certain mitigation measures 

must be completed. These measures are not vague as to how 

they will be enforced; the County will enforce them during the 

approval process of future nonresidential development.6 Indeed, 

 

6 The Statement and MMP have this language: “The 

following guidelines shall be used by the County during review 

of future project-specific submittals for non-residential 

development within the Specific Plan area and within the 

Community Plan boundary in order to reduce generation of air 

pollutants with intent that specified measures be required 

where feasible and appropriate.” To clarify, this aspect of the 

Statement and MMP deals with the specific air quality issues 

discussed in the EIR, which issues are considered “nonresidential.” The off-site created HVAC catalyst systems (that 

are eventually inserted into each home), tree planting, bicycle 

trails, and any other mitigation that affects air quality and 

comprises this aspect of the MMP are considered “nonresidential development” for architecture and engineering 

planning purposes. Of course, they each are part of the greater 

“residential development” in the project, but for EIR purposes 
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

32

if the County were to approve a project that did not include a 

feasible mitigation measure, such approval would amount to an 

abuse of discretion, which could be corrected in a court 

mandamus proceeding. (See Rominger v. County of Colusa 

(2014) 229 Cal.App.4th 690, 727 [holding dust control mitigation 

measures left to the county’s discretion are enforceable through 

a judicial writ of mandamus]; see also, e.g., California Oak 

Foundation v. Regents of University of California (2010) 188 

Cal.App.4th 227, 247.)

CONCLUSION

In our view, the EIR’s air quality impacts discussion and 

its mitigation measures meet CEQA requirements for specificity 

and enforceability with one exception: The EIR fails to provide 

an adequate discussion of health and safety problems that will 

be caused by the rise in various pollutants resulting from the 

Project’s development. At this point, we cannot know whether 

the required additional analysis will disclose that the Project’s

effects on air quality are less than significant or unavoidable, or

whether that analysis will require reassessment of proposed 

mitigation measures. Absent an analysis that reasonably

informs the public how anticipated air quality effects will 

adversely affect human health, an EIR may still be sufficient if 

it adequately explains why it is not scientifically feasible at the 

time of drafting to provide such an analysis. Otherwise, the EIR 

is generally clear about the potential environmental harm under 

the Specific Plan, and it outlined mitigation measures to address 

those effects with factual support and scientific consensus.

 

are considered “non-residential” since they involve cleaning the 

air, planting trees, and creating bicycle trails.
SIERRA CLUB v. COUNTY OF FRESNO

Opinion of the Court by Chin, J.

33

Based on the foregoing analysis, we affirm in part and 

reverse in part the Court of Appeal’s judgment and remand the 

matter for additional proceedings consistent with this opinion.

CHIN, J.

We Concur:

CANTIL-SAKAUYE, C. J.

CORRIGAN, J.

LIU, J.

CUÉLLAR, J.

KRUGER, J.

ROBIE, J.*

 

* Associate Justice of the Court of Appeal, Third Appellate 

District, assigned by the Chief Justice pursuant to article VI, 

section 6 of the California Constitution.
See last page for addresses and telephone numbers for counsel who argued in Supreme Court.

Name of Opinion Sierra Club v. County of Fresno

__________________________________________________________________________________

Unpublished Opinion

Original Appeal

Original Proceeding

Review Granted XXX 226 Cal.App.4th 704

Rehearing Granted

__________________________________________________________________________________

Opinion No. S219783

Date Filed: December 24, 2018

__________________________________________________________________________________

Court: Superior

County: Fresno

Judge: Rosendo Pena, Jr.

__________________________________________________________________________________

Counsel:

Law Office of Sara Hedgpeth-Harris, Sara Hedgpeth-Harris; Brandt-Hawley Law Group and Susan BrandtHawley for Plaintiffs and Appellants.

Chatten-Brown & Carstens, Jan Chatten-Brown, Douglas P. Carstens and Amy C. Minteer for Association 

of Irritated Residents, Medial Advocates for Healthy Air and Coalition for Clean Air as Amici Curiae on 

behalf of Plaintiffs and Appellants.

Michael W. Graf for Center for Biological Diversity as Amicus Curiae on behalf of Plaintiffs and 

Appellants.

Law Offices of Stephan C. Volker, Stephan C. Volker and Daniel P. Garrett-Steinman for North Coast 

Rivers Alliance as Amicus Curiae on behalf of Plaintiffs and Appellants.

Ashley E. Werner and Phoebe S. Seaton for Leadership Counsel for Justice and Accountability as Amicus 

Curiae on behalf of Plaintiffs and Appellants.

Kevin B. Briggs, County Counsel, and Bruce B. Johnson, Principal Deputy County Counsel, for 

Defendants and Respondents.

Remy Moose Manley, James G. Moose, Tiffany K. Wright and Laura M. Harris for Real Party in Interest.

Catherine T. Redmond and Annette Ballatore-Williamson for San Joaquin Valley Unified Air Pollution 

Control District as Amicus Curiae on behalf of Defendants and Respondents and Real Party in Interest.

The Sohagi Law Group, Margaret M. Sohagi and Philip A. Seymour for League of California Cities, 

California State Association of Counties, California Special Districts Association and Association of 

California Water Agencies as Amici Curiae on behalf of Real Party in Interest.

Brownstein Hyatt Farber Schreck and Lisabeth D. Rothman for California Building Industry Association 

and Building Industry Legal Defense Foundation as Amici Curiae on behalf of Real Party in Interest.
Page 2 – S219783 – counsel continued

Counsel:

Best Best & Krieger, Jason M. Ackerman and Fernando Avila for California Association of Environmental 

Professionals and American Planning Association California Chapter as Amici Curiae on behalf of Real 

Party in Interest.

Kurt R. Wiese and Barbara Baird for South Coast Air Quality Management District as Amicus Curiae.
Counsel who argued in Supreme Court (not intended for publication with opinion):

Sara Hedgpeth-Harris

Law Office of Sara Hedgpeth-Harris

2115 Kern Street, Suite 1

Fresno, CA 93721

(559) 510-1259

Susan Brandt-Hawley

Brandt-Hawley Law Group

P.O. Box 1659

Glen Ellen, CA 95442

(707) 938-3900

James G. Moose

Remy Moose Manley

555 Capitol Mall, Suite 800

Sacramento, CA 95814

(916) 443-2745