We must decide whether recyclers challenging a local ordinance that bans a particular method of waste disposal have prudential standing to raise its constitutionality under the dormant 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 injection of sewage sludge below the land surface; or the incorporation of sewage sludge into the soil so that the sewage sludge can either *844 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”) 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 misdemeanor 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 disposal 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 Sanitation 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 destination, and asserting that this site change would result in increased transportation costs.
B
These out-of-county generators, along with waste transporters 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 dormant 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 California Water Code. They also asserted that it constituted an invalid exercise of Kern’s police power. The district court initially 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 injunction halting enforcement of Measure E. The parties filed cross motions for summary judgment.
The district court granted Kern’s motion for summary judgment on the recyclers’ equal protection claim, and denied summary judgment on the police power claim, citing the existence of disputed facts. As for the dormant Commence Clause, the district court concluded that Measure E discriminated 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 jurisdiction 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
*845
dormant Commerce Clause. That inquiry involves “both constitutional limitations on federal-court jurisdiction and prudential limitations on its exercise.”
Warth v. Seldin,
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,
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,
The Seventh Circuit’s opinion in
Main-Street Organization of Realtors v. Calumet City,
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,
We recognize that at times, the “prudential objectives[] thought to be enhanced” by standing restrictions “cannot be furthered” by consideration of an unpreserved argument. See
Craig v. Boren,
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 unnecessary constitutional adjudication applies even when neither the trial court nor the parties have considered the nonconstitutional basis for decision.”
Correa v. Clayton,
Accordingly, we choose to exercise our discretion to rule on the recyclers’ prudential standing to bring this suit.
B
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 particular.”
Individuals for Responsible Gov’t, Inc. v. Washoe County,
Accordingly, to “ascertain whether [the recyclers] have standing to raise the dormant Commerce Clause challenge in the present case, [we] must ... determiner ] whether their interests bear more than a marginal relationship to the purposes 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.,
Our decision in
Washoe County
provides the answer to this question. In that case, we addressed Nevada county ordinances which required residents to employ garbage collection services run by “the County and its authorized agents or contractees.”
Washoe County,
Such analysis controls the case at hand. The interest the recyclers seek to secure is their ability to exploit a portion of the
intra
state 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 under
*848
lying [the dormant Commerce] Clause is to limit the power of States to erect barriers against
interstate
trade.”
Washoe County,
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,
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,
Accordingly, because the recyclers’ injury is not even “marginally related” to the interests the Clause seeks to safeguard, they lack prudential standing to bring their federal constitutional claim.
Ill
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 supplemental jurisdiction over the preemption claim,
see, e.g., Golden v. CH2M Hill Hanford Group, Inc.,
DISMISSED in part, VACATED in part, and REMANDED.
Notes
. 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 including] material derived from or containing sewage sludge such as compost and pelletized sewage sludge, irrespective of where generated, produced or treated.” The measure describes land application as "the spraying, spreading or other placement of Biosolids onto the land surface, the injection of Biosolids below the surface, or the incorporation of Biosolids into the soil.”
. Consequently, campaign literature supporting the passage of Measure E claimed that it would "stop L.A. from dumping on Kern."
. Other circuits have taken a different tack.
See Am. Immigration Lawyers Ass’n v. Reno,
. Kern’s appeal was confined to the district court's rulings on the federal constitutional question and state law preemption. We had concerns, however, 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.
. A state's political subdivisions are likewise precluded from impeding interstate commerce.
See, e.g., Carbone, 511 U.S.
at 390,
. The recyclers contend that they generally engage in interstate commerce and that the Supreme Court has described waste as an article of interstate commerce.
See Fort Gratiot,
. For this reason, the recyclers’ claims are more analogous to the claims of the residents in
Washoe County, see
. In
Ben Oehrleins & Sons & Daughter, Inc. v. Hennepin County,
