Title: Sierra Club v. County of Fresno
Citation: N/A
Docket Number: S219783
State: California
Issuer: California Supreme Court
Date: December 24, 2018

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 EIR2 that 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 self-
government.”  (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 on-
campus 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. 
SIERRA CLUB v. COUNTY OF FRESNO 
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 
SIERRA CLUB v. COUNTY OF FRESNO 
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 
SIERRA CLUB v. COUNTY OF FRESNO 
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 
SIERRA CLUB v. COUNTY OF FRESNO 
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 “non-
residential.”  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 “non-
residential 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 Brandt-
Hawley 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