                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

CITY OF LOS ANGELES; ORANGE            
COUNTY SANITATION DISTRICTS;
RESPONSIBLE BIOSOLIDS
MANAGEMENT, INC.; R & G
FANUCCHI INC.; SIERRA TRANSPORT
INC.; CALIFORNIA ASSOCIATION OF
SANITATION AGENCIES; SHAEN
MAGAN, individually and dba’s
Honey Bucket Farms; Tule
Ranch/Magan Farms; WESTERN
EXPRESS INC.,                                No. 07-56564

                                       
               Plaintiffs-Appellees,           D.C. No.
                and                        CV-06-05094-GAF
KERN COUNTY WATER AGENCY;                     OPINION
ASSOCIATION OF IRRITATED
RESIDENTS; ARVIN-EDISON WATER
STORAGE DISTRICT; KERN WATER
BANK AUTHORITY,
                      Intervenors,
                v.
COUNTY OF KERN; KERN COUNTY
BOARD OF SUPERVISORS,
            Defendants-Appellants.
                                       
        Appeal from the United States District Court
           for the Central District of California
          Gary A. Feess, District Judge, Presiding

           Argued and Submitted March 2, 2009
           Submission vacated March 19, 2009
             Resubmitted September 9, 2009
                   Pasadena, California

                            12859
12860         LOS ANGELES v. COUNTY OF KERN
                Filed September 9, 2009

 Before: Diarmuid F. O’Scannlain, Pamela Ann Rymer, and
          Kim McLane Wardlaw, Circuit Judges.

             Opinion by Judge O’Scannlain
12862          LOS ANGELES v. COUNTY OF KERN
                         COUNSEL

Steven L. Mayer, Howard Rice Nemerovski Canady Falk &
Rabkin, San Francisco, California, argued the cause for
defendants-appellants and filed the briefs. Jerome B. Falk, Jr.
and Adam Polakoff, Howard Rice Nemerovski Canady Falk
& Rabkin, San Francisco, California; Bernard C. Barmann
and Stephen D. Schuett, County of Kern, Bakersfield, Califor-
nia; and Michael M. Hogan, Hogan Guiney Dick LLP, San
Diego, California, were also on the briefs.

Thomas S. Hixon, Bingham McCutchen LLP, Los Angeles,
California, argued the cause for plaintiffs-appellees and was
on the briefs. James J. Dragna and Marc R. Bruner, Bingham
McCutchen LLP, Los Angeles, California; Rockard J. Del-
gadillo, Christopher M. Westhoff, and Keith W. Pritsker, City
of Los Angeles, Los Angeles, California; James B. Slaughter
and Gary J. Smith, Washington, District of Columbia; Daniel
V. Hyde and Paul J. Beck, Lewis Brisbois Bisgaard & Smith
LLP, Los Angeles, California; Bradley R. Hogin, Woodruff
Spradlin & Smart, Orange, California; Michael J. Lampe,
Law Offices of Michael J. Lampe, Visalia, California; and
Roberta L. Larson and Jonathan Schutz, Somach Simmons &
Dunn, Sacramento, California, were also on the briefs.

James Sullivan, Water Environment Federation, Alexandria,
Virginia, filed a brief on behalf of Amicus Curiae Water
Environment Federation.

Keith J. Jones, National Association of Clean Water Agen-
cies, Washington, District of Columbia, filed a brief on behalf
of Amicus Curiae National Association of Clean Water Agen-
cies. Nathan Gardner-Andrews, National Association of Clean
Water Agencies, Washington, District of Columbia, was also
on the brief.
                   LOS ANGELES v. COUNTY OF KERN                     12863
                               OPINION

O’SCANNLAIN, Circuit Judge:

  We must decide whether recyclers challenging a local ordi-
nance that bans a particular method of waste disposal have
prudential standing to raise its constitutionality under the dor-
mant Commerce Clause.

                                     I

                                    A

   The fact that the subject matter of the case before us
involves sewage sludge will be of no surprise to those familiar
with the negative implications of the Commerce Clause. For
our purposes, sludge is the “solid, semi-solid, or liquid residue
generated during the treatment of domestic sewage.” 40
C.F.R. § 503.9(w). Here, we deal with the “land application”
of “biosolids”: essentially, a particular recycling method
which involves the use of treated sludge as fertilizer.1 See 40
C.F.R. § 503.11(h) (“Land application is the spraying or
spreading of sewage sludge onto the land surface; the injec-
tion of sewage sludge below the land surface; or the incorpo-
ration of sewage sludge into the soil so that the sewage sludge
can either condition the soil or fertilize crops or vegetation
grown in the soil.”).

  In 2006, voters in Kern County, California (“Kern”),
adopted a local ordinance (“Measure E” or the “Ordinance”)
  1
    The local ordinance before us defines biosolids as “treated solid, semi-
solid or liquid residues generated during the treatment of sewage in a
wastewater treatment works and includ[ing] material derived from or con-
taining sewage sludge such as compost and pelletized sewage sludge, irre-
spective of where generated, produced or treated.” The measure describes
land application as “the spraying, spreading or other placement of Bio-
solids onto the land surface, the injection of Biosolids below the surface,
or the incorporation of Biosolids into the soil.”
12864            LOS ANGELES v. COUNTY OF KERN
by ballot initiative that makes it “unlawful for any person to
Land Apply Biosolids to property within the unincorporated
area of the County.” Violation of the Ordinance is a misde-
meanor punishable by “a fine of not more than $500 or by
imprisonment of not more than six months.” By its terms, the
Ordinance applies to both in-county and out-of-county waste
generators. In practical effect, however, because Kern does
not currently apply its biosolids to land within the county,
Measure E does not directly impact Kern’s own waste dis-
posal programs.

   Prior to the Ordinance, in-state waste generators frequently
disposed of their biosolids by land application at various
farms throughout the unincorporated area of Kern County.2
For example, the City of Los Angeles, Orange County Sanita-
tion District, and County Sanitation District No. 2 of Los
Angeles County ship large amounts of waste generated by
their residents to Green Acres, Honey Bucket Farms, and Tule
Ranch. If these generators were precluded from land applying
their biosolids in Kern County, they would be required to find
alternative locations to dispose of their sludge. They have
submitted declarations pointing to Arizona as a probable des-
tination, and asserting that this site change would result in
increased transportation costs.

                                  B

   These out-of-county generators, along with waste transport-
ers and in-county farmers (collectively, “the recyclers”), filed
suit in the United States District Court for the Central District
of California. They alleged that Measure E violated the dor-
mant Commerce Clause and the Equal Protection Clause and
was preempted by the Federal Clean Water Act, the California
Integrated Waste Management Act (“CIWMA”), and the Cali-
fornia Water Code. They also asserted that it constituted an
  2
   Consequently, campaign literature supporting the passage of Measure
E claimed that it would “stop L.A. from dumping on Kern.”
                LOS ANGELES v. COUNTY OF KERN             12865
invalid exercise of Kern’s police power. The district court ini-
tially dismissed the Clean Water Act and the California Water
Code claims under Federal Rule of Civil Procedure 12(b)(6),
while granting the recyclers’ request for a preliminary injunc-
tion halting enforcement of Measure E. The parties filed cross
motions for summary judgment.

   The district court granted Kern’s motion for summary judg-
ment on the recyclers’ equal protection claim, and denied
summary judgment on the police power claim, citing the exis-
tence of disputed facts. As for the dormant Commence
Clause, the district court concluded that Measure E discrimi-
nated against interstate commerce in effect. Accordingly, the
court applied strict scrutiny, determined the Ordinance could
not survive, and granted summary judgment in favor of the
recyclers. The district court also exercised supplemental juris-
diction over the recyclers’ CIWMA claim under 28 U.S.C.
§ 1367 and held that Measure E was preempted by state law.

  Kern timely filed this appeal, challenging only the district
court’s rulings on the dormant Commerce Clause and state-
law preemption claims.

                               II

   We first assess whether the recyclers have standing to bring
suit under the dormant Commerce Clause. That inquiry
involves “both constitutional limitations on federal-court
jurisdiction and prudential limitations on its exercise.” Warth
v. Seldin, 422 U.S. 490, 498 (1975). “Constitutional [or “Arti-
cle III”] standing concerns whether the plaintiff’s personal
stake in the lawsuit is sufficient to make out a concrete ‘case’
or ‘controversy’ to which the federal judicial power may
extend under Article III, § 2.” Pershing Park Villas Home-
owners Ass’n v. United Pac. Ins. Co., 219 F.3d 895, 899 (9th
Cir. 2000); see also Lujan v. Defenders of Wildlife, 504 U.S.
555, 559-60 (1992). These limits are jurisdictional: they can-
not be waived by any party, and there is no question that a
12866              LOS ANGELES v. COUNTY OF KERN
court can, and indeed must, resolve any doubts about this con-
stitutional issue sua sponte. See, e.g., Indep. Living Ctr. of S.
Cal., Inc. v. Shewry, 543 F.3d 1050, 1064-65 (9th Cir. 2008).
Here, no party contends the recyclers lack Article III standing,
and we are independently satisfied that they have met the
requirements of Lujan.

   Over and above the limits of Article III, however, there
exists a body of “judicially self-imposed limits on the exercise
of federal jurisdiction,” Allen v. Wright, 468 U.S. 737, 751
(1984), “founded in concern about the proper—and properly
limited—role of the courts in a democratic society,” Warth,
422 U.S. at 498. Citing their nonconstitutional nature, we
have previously held that these requirements, commonly
referred to as “prudential” standing, “can be deemed waived
if not raised in the district court.” Bd. of Natural Res. v.
Brown, 992 F.2d 937, 946 (9th Cir. 1993).3

                                     A

  Because Kern admittedly failed to raise prudential standing
before the district court,4 we must satisfy ourselves that we
should address the matter in the first instance. At times, we
have exercised our prerogative to “deem” this issue waived in
such circumstances. See, e.g., Laub v. U.S. Dep’t of Interior,
342 F.3d 1080, 1087 n.6 (9th Cir. 2003); Pershing Park, 219
F.3d at 899-900. Past practice, however, does not preclude
  3
     Other circuits have taken a different tack. See Am. Immigration Law-
yers Ass’n v. Reno, 199 F.3d 1352, 1357-58 (D.C. Cir. 2000) (prudential
standing is non-waivable); Cmty. First Bank v. Nat’l Credit Union Admin.,
41 F.3d 1050, 1053 (6th Cir. 1994) (same); Thompson v. County of Frank-
lin, 15 F.3d 245, 248 (2d Cir. 1994) (same).
   4
     Kern’s appeal was confined to the district court’s rulings on the federal
constitutional question and state law preemption. We had concerns, how-
ever, as to whether the recyclers had prudential standing to bring this
claim under the dormant Commerce Clause. Accordingly, we directed the
parties to discuss the issue at oral argument and requested that they file
supplemental briefs.
                LOS ANGELES v. COUNTY OF KERN              12867
our consideration of the subject in the case at hand. Rather,
the permissive language in our caselaw—“can be deemed”—
indicates that the choice to reach the question lies within our
discretion. We are also mindful of the Supreme Court’s
description of constitutional and prudential standing as
“threshold determinants of the propriety of judicial interven-
tion.” Warth, 422 U.S. at 518.

   The Seventh Circuit’s opinion in Mainstreet Organization
of Realtors v. Calumet City, 505 F.3d 742 (7th Cir. 2007), is
instructive. In that case, the court reached the issue of pruden-
tial standing, despite the “wrinkle” that “the City did not
argue [prudential standing] until [the panel] raised the issue at
oral argument.” Id. at 747. “[N]onconstitutional lack of stand-
ing,” according to the Seventh Circuit, “belongs to an inter-
mediate class of cases in which a court can notice an error and
reverse on the basis of it even though no party has noticed it
and the error is not jurisdictional, at least in the conventional
sense.” Id.; see also id. at 747-48 (citing failure to exhaust
state remedies in habeas cases and abstention as examples);
cf. Tenet v. Doe, 544 U.S. 1, 6 n.4 (2005) (“[A]pplication of
the Totten rule of dismissal, like the abstention doctrine . . .
or the prudential standing doctrine, represents the sort of
‘threshold question’ we have recognized may be resolved
before addressing jurisdiction.” (emphasis added) (citation
omitted)).

   Thus, we may cite a party’s “failure to invoke [prudential
standing]” as “a ground for refusing to invoke it” on our own
initiative: such failure, however, does not bar our examination
of the matter. Mainstreet, 505 F.3d at 749. “In other words,
[we] may raise an unpreserved prudential-standing question
on [our] own, but unlike questions of constitutional standing,
[we are] not obliged to do so.” Rawoof v. Texor Petroleum
Co., 521 F.3d 750, 757 (7th Cir. 2008).

  We recognize that at times, the “prudential objectives[ ]
thought to be enhanced” by standing restrictions “cannot be
12868           LOS ANGELES v. COUNTY OF KERN
furthered” by consideration of an unpreserved argument. See
Craig v. Boren, 429 U.S. 190, 193-94 (1976). Here, we have
provided the parties with an opportunity fully to brief the
issue, and further development of the record would not aid
our decisionmaking process. Those briefs indicate that at least
one of the parties (Kern) “resist[s]” an “authoritative . . .
determination” by this court. Id. at 193. Our disposition of the
prudential standing question might also affect the district
court’s decision under 28 U.S.C. § 1367 to exercise jurisdic-
tion over the state-law claims.

   Perhaps most importantly, a ruling on prudential standing
could obviate the need to rule on the merits of the dormant
Commerce Clause challenge. In such circumstances, “we are
guided by the traditional principle that a federal court should
not decide federal constitutional questions where a dispositive
nonconstitutional ground is available. This rule against unnec-
essary constitutional adjudication applies even when neither
the trial court nor the parties have considered the nonconstitu-
tional basis for decision.” Correa v. Clayton, 563 F.2d 396,
400 (9th Cir. 1977) (internal quotation marks and citations
omitted).

   [1] Accordingly, we choose to exercise our discretion to
rule on the recyclers’ prudential standing to bring this suit.

                                B

   [2] Several doctrines fall under the rubric of “prudential
standing.” Here, we consider only “the zone of interests test[,
which] governs claims under the Constitution in general, and
under the negative [dormant] Commerce Clause in particu-
lar.” Individuals for Responsible Gov’t, Inc. v. Washoe
County, 110 F.3d 699, 703 (9th Cir. 1997) (second alteration
in original) (internal quotation marks and citation omitted);
see also Clarke v. Sec. Indus. Ass’n, 479 U.S. 388, 396 (1987)
(noting that interests must be “arguably within the zone of
interests to be protected or regulated by the statute or constitu-
                  LOS ANGELES v. COUNTY OF KERN                   12869
tional guarantee in question” (internal quotation marks and
citation omitted)). While the test “is not meant to be espe-
cially demanding,” Clarke, 479 U.S. at 399, a party’s “com-
plaint must ‘fall within the zone of interests to be protected
or regulated by the statute or constitutional guarantee in ques-
tion.’ ” Washoe County, 110 F.3d at 703 (quoting Valley
Forge Christian Coll. v. Ams. United for Separation of
Church & State, Inc., 454 U.S. 464, 475 (1982)). Thus, this
prudential standing requirement “denies a right of review if
the plaintiff’s interests are . . . marginally related to or incon-
sistent with the purposes implicit in the [relevant constitu-
tional provision].” Id. (alterations in original) (internal
quotation marks and citation omitted).

   [3] Accordingly, to “ascertain whether [the recyclers] have
standing to raise the dormant Commerce Clause challenge in
the present case, [we] must . . . determine[ ] whether their
interests bear more than a marginal relationship to the pur-
poses underlying the dormant Commerce Clause.” Id. We
have previously concluded that the “chief purpose underlying
[the] Clause is to limit the power of States to erect barriers
against interstate trade.” Id. (internal quotation marks and
citation omitted); see also Fort Gratiot Sanitary Landfill, Inc.
v. Mich. Dep’t of Natural Res., 504 U.S. 353, 359 (1992)
(“[T]he ‘negative’ or ‘dormant’ aspect of the Commerce
Clause prohibits States from ‘advanc[ing] their own commer-
cial interests by curtailing the movement of articles of com-
merce, either into or out of the state.’ ” (alternation in
original) (quoting H.P. Hood & Sons, Inc. v. Du Mond, 336
U.S. 525, 535 (1949))).5 The question, therefore, is whether
the recyclers’ claims “bear more than a marginal relationship”
to claims addressing a state or county’s effort to erect barriers
to interstate commerce.
  5
    A state’s political subdivisions are likewise precluded from impeding
interstate commerce. See, e.g., Carbone, 511 U.S. at 390.
12870           LOS ANGELES v. COUNTY OF KERN
   Our decision in Washoe County provides the answer to this
question. In that case, we addressed Nevada county ordi-
nances which required residents to employ garbage collection
services run by “the County and its authorized agents or con-
tractees.” Washoe County, 110 F.3d at 701. “[P]rior to enact-
ment of the ordinances, [some residents had] transported their
garbage across state lines for disposal at the dump sites in . . .
California.” Id. at 703. Displeased with paying for a service
they did not desire, these residents brought suit, alleging that
the ordinance violated the dormant Commerce Clause insofar
as it “prevent[ed] them from utilizing dump sites outside the
State of Nevada.” Id. at 702. We held that though the resi-
dents met the constitutional requirements for standing, they
failed to satisfy the prudential limitations. Id. at 702, 704.
Paying for unwanted garbage collection services—even if one
had previously dumped out of state—was “an injury not even
marginally related to the purposes underlying” the Clause. Id.
at 703. We posited that even if all residents forced to pay for
garbage collection services had previously transported their
waste across state lines, the litigants’ claim could not meet the
zone of interests test. “Their injury (being forced to pay for
services they did not want) would exist even if the [garbage
collection service] were to dump all the garbage it collects
from Nevada across the state line in California. Under those
circumstances, the Washoe County ordinance would impose
no barrier to interstate commerce.” Id. at 703-04; see also On
the Green Apartments L.L.C. v. City of Tacoma, 241 F.3d
1235, 1239-40 (9th Cir. 2001) (reaching the same conclusion
with respect to a similar waste disposal ordinance).

   [4] Such analysis controls the case at hand. The interest the
recyclers seek to secure is their ability to exploit a portion of
the intrastate waste market—they want to be able to ship their
waste from one portion of California to another. But as we
have said, the “chief purpose underlying [the dormant Com-
merce] Clause is to limit the power of States to erect barriers
against interstate trade.” Washoe County, 110 F.3d at 703
(emphasis added) (internal quotation marks and citation omit-
                   LOS ANGELES v. COUNTY OF KERN                     12871
ted). Nothing in Measure E hampers the recyclers’ ability to
ship waste out of state. Likewise, no recycler claims to apply
out-of-state waste to land in Kern County. In short, Measure
E in no way burdens the recyclers’ protected interest in the
interstate waste market. We decline to expand the zone of
interests protected by the Clause to purely intrastate disputes.

   [5] The recyclers miss the point when they contend that if
Measure E stands, some of them will be forced to pay higher
fees to ship their waste to different sites, likely in Arizona.
While this injury-in-fact suffices for Article III purposes, see
Washoe County, 110 F.3d at 702, it is insufficient to establish
prudential standing. As the name implies, the zone of interests
test turns on the interest sought to be protected, not the harm
suffered by the plaintiff. See Ass’n of Data Processing Serv.
Orgs., Inc. v. Camp, 397 U.S. 150, 153 (1970) (“[The zone of
interests test] concerns . . . the question whether the interest
sought to be protected by the complainant is arguably . . . pro-
tected or regulated by the statute or constitutional guarantee
in question.” (emphasis added)). Financial injury, standing
alone, does not implicate the zone of interests protected by the
dormant Commerce Clause. That financial injury must some-
how be tied to a barrier imposed on interstate commerce. The
recyclers here have not established that requisite link.6 Like
the residents in Washoe County, they would suffer the same
injury (being forced to pay higher prices for biosolid disposal)
if Measure E permitted land application from out-of-state
entities, but prohibited land application from in-state entities.
“Under those circumstances,” Measure E would “impose no
barrier to interstate commerce,” Washoe County, 110 F.3d at
704, yet the harm to the recyclers would be the same.7 There-
  6
     The recyclers contend that they generally engage in interstate com-
merce and that the Supreme Court has described waste as an article of
interstate commerce. See Fort Gratiot, 504 U.S. at 359. Neither fact, how-
ever, links the financial injury they allege in this case with an impediment
to interstate commerce.
   7
     For this reason, the recyclers’ claims are more analogous to the claims
of the residents in Washoe County, see 110 F.3d at 703; On the Green, 241
12872              LOS ANGELES v. COUNTY OF KERN
fore, we cannot conclude that the recyclers alleged injury is
tied to the purposes animating the dormant Commerce Clause.

   In their supplemental brief, the recyclers discuss a number
of cases where courts have determined that in-state plaintiffs
have prudential standing to bring suit under the dormant
Commerce Clause. See, e.g., Carbone, 511 U.S. at 387-88;
Gen. Motors Corp. v. Tracy, 519 U.S. 278, 286-87 (1997);
Or. Waste Sys., Inc. v. Dep’t of Envtl. Quality, 511 U.S. 93,
97-98 (1994); Huish Detergents, 214 F.3d at 711-12. All of
those cases, however, involve impediments to in-state plain-
tiffs’ access to out-of-state markets, restrictions on the ability
of out-of-state entities to make use of in-state plaintiffs’ ser-
vices, or burdens on out-of-state entities which were passed
on to in-state plaintiffs. See Carbone, 511 U.S. at 388; Tracy,
519 U.S. at 286-87; Or. Waste Sys., 511 U.S. at 96-97; Huish
Detergents, 214 F.3d at 711.8 No such allegations are present
in this case. Rather, the recyclers either contend that Measure
E prevents them from shipping their waste intrastate, or that
they are denied the benefits of such shipments. As we have
discussed above, such circumstances do not implicate the
interests protected by the dormant Commerce Clause.

  [6] Accordingly, because the recyclers’ injury is not even
“marginally related” to the interests the Clause seeks to safe-

F.3d at 1239-40, than the apartment complex in On the Green, see 241
F.3d at 1241. Moreover, the ordinance in On the Green barred the plaintiff
from engaging in interstate commerce. Measure E creates no such prohibi-
tion. Cf. Huish Detergents, Inc. v. Warren County, 214 F.3d 707, 711 (6th
Cir. 2000) (concluding that prudential standing was established when
plaintiffs’ financial injury would disappear “if it could hire a waste hauler
to transport its waste out-of-state“ (emphasis added)).
   8
     In Ben Oehrleins & Sons & Daughter, Inc. v. Hennepin County, 115
F.3d 1372 (8th Cir. 1997), the Eighth Circuit found that in-state haulers
and processors had standing to challenge a local ordinance that required
waste designated for in-state disposal to pass through designated facilities.
Id. at 1377-79. That decision was made in a single, conclusory sentence,
which we decline to follow. Id. at 1379.
                LOS ANGELES v. COUNTY OF KERN                 12873
guard, they lack prudential standing to bring their federal con-
stitutional claim.

                                 III

   [7] Based on the foregoing, we dismiss the recyclers’
claims under the dormant Commerce Clause. With that, we
are left with a complex question of state-law preemption.
Because our dismissal of the federal constitutional claim may
materially alter the district court’s decision to exercise supple-
mental jurisdiction over the preemption claim, see, e.g., Gol-
den v. CH2M Hill Hanford Group, Inc., 528 F.3d 681, 684
(9th Cir. 2008), we vacate its judgment and remand the state-
law claim for reconsideration of the factors listed in 28 U.S.C.
§ 1367.

  DISMISSED        in    part,    VACATED       in    part,    and
REMANDED.
