Opinion
CORRIGAN, J.
Under our state Constitution, if the Legislature or a state agency requires a local government to provide a new program or higher level of service, the local government is entitled to reimbursement from the state for the associated costs. (Cal. Const., art. XIII B, § 6, subd. (a).) There are exceptions, however. Under one of them, if the new program or increased service is mandated by a federal law or regulation, reimbursement is not required. (Gov. Code, § 17556, subd. (c).)
The services in question here are provided by local agencies that operate storm drain systems pursuant to a state-issued permit. Conditions in that permit are designed to maintain the quality of California’s water, and to comply with the federal Clean Water Act (33 U.S.C. § 1251 et seq.). The Court of Appeal held that certain permit conditions were federally mandated, and thus not reimbursable. We reverse, concluding that no federal law or regulation imposed the conditions nor did the federal regulatory system require the state to impose them. Instead, the permit conditions were imposed as a result of the state’s discretionary action.
I. Background
The Regional Water Quality Control Board, Los Angeles Region (the Regional Board or the Board) is a state agency. It issued a permit authorizing Los Angeles County, the Los Angeles County Flood Control District, and 84 cities (collectively, the Operators) to operate storm drainage systems.1 Permit [755]*755conditions required that the Operators take various steps to reduce the discharge of waste and pollutants into state waters. The conditions included installing and maintaining trash receptacles at transit stops, as well as inspecting certain commercial and industrial facilities and construction sites.
Some Operators sought reimbursement for the cost of satisfying the conditions. The Commission on State Mandates (the Commission) concluded each required condition was a new program or higher level of service, mandated by the state rather than by federal law. However, it found the Operators were only entitled to state reimbursement for the costs of the trash receptacle condition, because they could levy fees to cover the costs of the required inspections. (See discussion, post, at p. 761.) The trial court and the Court of Appeal disagreed, finding that all of the requirements were federally mandated.
We granted review. To resolve this issue, it is necessary to consider both the permitting system and the reimbursement obligation in some detail.
A. The Permitting System
The Operators’ municipal storm sewer systems discharge both waste and pollutants.2 State law controls “waste” discharges. (Wat. Code, § 13265.) Federal law regulates discharges of “pollutant[s].” (33 U.S.C. § 1311(a).) Both state and later-enacted federal law require a permit to operate such systems.
California’s Porter-Cologne Water Quality Control Act (Porter-Cologne Act or the Act; Wat. Code, § 13000 et seq.) was enacted in 1969. It established the State Water Resources Control Board (State Board), along with nine regional water quality control boards, and gave those agencies “primary responsibility for the coordination and control of water quality.” (Wat. Code, § 13001; see City of Burbank v. State Water Resources Control Bd. (2005) 35 Cal.4th 613, 619 [26 Cal.Rptr.3d 304, 108 P.3d 862] (City of Burbank).) The State Board establishes statewide policy. The regional boards formulate and [756]*756adopt water quality control plans and issue permits governing the discharge of waste. (Building Industry Assn. of San Diego County v. State Water Resources Control Bd. (2004) 124 Cal.App.4th 866, 875 [22 Cal.Rptr.3d 128] (Building Industry).)
The Porter-Cologne Act requires any person discharging, or proposing to discharge, waste that could affect the quality of state waters to file a report with the appropriate regional board. (Wat. Code, § 13260, subd. (a)(1).) The regional board then “shall prescribe requirements as to the nature” of the discharge, implementing any applicable water quality control plans. (Wat. Code, § 13263, subd. (a).) The Operators must follow all requirements set by the regional board. (Wat. Code, §§ 13264, 13265.)
The federal Clean Water Act (the CWA; 33 U.S.C. § 1251 et seq.) was enacted in 1972, and also established a permitting system. The CWA is a comprehensive water quality statute designed to restore and maintain the chemical, physical, and biological integrity of the nation’s waters. (City of Burbank, supra, 35 Cal.4th at p. 620.) The CWA prohibits pollutant discharges unless they comply with: (1) a permit (see 33 U.S.C. §§ 1328, 1342, 1344); (2) established effluent limitations or standards (see 33 U.S.C. §§ 1312, 1317); or (3) established national standards of performance (see 33 U.S.C. § 1316). (See 33 U.S.C. § 1311(a).) The CWA allows any state to adopt and enforce its own water quality standards and limitations, so long as those standards and limitations are not “less stringent” than those in effect under the CWA. (33 U.S.C. § 1370.)
The CWA created the National Pollutant Discharge Elimination System (NPDES), authorizing the Environmental Protection Agency (EPA) to issue a permit for any pollutant discharge that will satisfy all requirements established by the CWA or the EPA Administrator. (33 U.S.C. § 1342(a)(1), (2).) The federal system notwithstanding, a state may administer its own permitting system if authorized by the EPA.3 If the EPA concludes a state has adequate authority to administer its proposed program, it must grant approval (33 U.S.C. § 1342(b)) and suspend its own issuance of permits (33 U.S.C. § 1342(c)(1)).4
[757]*757California was the first state authorized to issue its own pollutant discharge permits. (California ex rel. State Water Resources Control Bd. v. Environmental Protection Agency (9th Cir. 1975) 511 F.2d 963, 970, fn. 11, revd. on other grounds in EPA v. State Water Resources Control Board (1976) 426 U.S. 200 [48 L.Ed.2d 578, 96 S.Ct. 2022].) Shortly after the CWA’s enactment, the Legislature amended the Porter-Cologne Act, adding chapter 5.5 (Wat. Code, § 13370 et seq.) to authorize state issuance of permits (Wat. Code, § 13370, subd. (c)). The Legislature explained the amendment was “in the interest of the people of the state, in order to avoid direct regulation by the federal government of persons already subject to regulation under state law pursuant to [the Porter-Cologne Act].” (Ibid.) The Legislature provided that chapter 5.5 be “construed to ensure consistency” with the CWA. (Wat. Code, § 13372, subd. (a).) It directed that state and regional boards issue waste discharge requirements “ensuring] compliance with all applicable provisions of the [CWA] . . . together with any more stringent effluent standards or limitations necessary to implement water quality control plans, or for the protection of beneficial uses, or to prevent nuisance.” (Wat. Code, § 13377, italics added.) To align the state and federal permitting systems, the legislation provided that the term “ ‘waste discharge requirements’ ” under the Act was equivalent to the term “ ‘permits’ ” under the CWA. (Wat. Code, § 13374.) Accordingly, California’s permitting system now regulates discharges under both state and federal law. (WaterKeepers Northern California v. State Water Resources Control Bd. (2002) 102 Cal.App.4th 1448, 1452 [126 Cal.Rptr.2d 389]; accord, Building Industry, supra, 124 Cal.App.4th at p. 875.)
In 1987, Congress amended the CWA to clarify that a permit is required for any discharge from a municipal storm sewer system serving a population of 100,000 or more. (33 U.S.C. § 1342(p)(2)(C), (D).) Under those amendments, a permit may be issued either on a system- or jurisdiction-wide basis, must effectively prohibit non-stormwater discharges into the storm sewers, and must “require controls to reduce the discharge of pollutants to the maximum extent practicable(33 U.S.C. § 1342(p)(3)(B), italics added.) The phrase “maximum extent practicable” is not further defined. How that phrase is applied, and by whom, are important aspects of this case.
EPA regulations specify the information to be included in a permit application. (See 40 C.F.R. § 122.26(d)(l)(i)-(vi), (2)(i)—(viii).) Among other things, an applicant must set out a proposed management program that includes management practices; control techniques; and system, design, and engineering methods to reduce the discharge of pollutants to the maximum extent practicable. (40 C.F.R. § 122.26(d)(2)(iv).) The permit-issuing agency has discretion to determine which practices, whether or not proposed by the applicant, will be imposed as conditions. {Ibid.)
[758]*758B. The Permit in Question
In 2001, Los Angeles County (the County), acting for all Operators, applied for a permit from the Regional Board. The Board issued a permit (the Permit), with conditions intended to “reduce the discharge of pollutants in storm water to the Maximum Extent Practicable” in the Operators’ jurisdiction. The Permit stated that its conditions implemented both the Porter-Cologne Act and the CWA.
Part 4 of the Permit contains the four requirements at issue. Part 4.C addresses commercial and industrial facilities, and required the Operators to inspect certain facilities twice during the five-year term of the Permit. Inspection requirements were set out in substantial detail.5 Part 4.E of the Permit addresses construction sites. It required each Operator to “implement a program to control runoff from construction activity at all construction sites within its jurisdiction,” and to inspect each construction site of one acre or greater at least “once during the wet season.”6 Finally, Part 4.F of the Permit addresses pollution from public agency activities. Among other things, it directed each Operator not otherwise regulated to “[pjlace trash receptacles at all transit stops within its jurisdiction,” and to maintain them as necessary.
C. Local Agency Claims
1. Applicable procedures for seeking reimbursement
As mentioned, when the Legislature or a state agency requires a local government to provide a new program or higher level of service, the state must “reimburse that local government for the costs of the program or increased level of service.” (Cal. Const., art. XIII B, § 6, subd. (a) (hereafter, [759]*759section 6).)7 However, reimbursement is not required if ‘“[t]he statute or executive order imposes a requirement that is mandated by a federal law or regulation and results in costs mandated by the federal government, unless the statute or executive order mandates costs that exceed the mandate in that federal law or regulation.” (Gov. Code, § 17556, subd. (c).)
The Legislature has enacted comprehensive procedures for the resolution of reimbursement claims (Gov. Code, § 17500 et seq.) and created the Commission to adjudicate them (Gov. Code, §§ 17525, 17551). It also established ‘“a test-claim procedure to expeditiously resolve disputes affecting multiple agencies.” (Kinlaw v. State of California (1991) 54 Cal.3d 326, 331 [285 Cal.Rptr. 66, 814 P.2d 1308] (Kinlaw).)
The first reimbursement claim filed with the Commission is called a test claim. (Gov. Code, § 17521.) The Commission must hold a public hearing, at which the Department of Finance (the Department), the claimant, and any other affected department or agency may present evidence. (Gov. Code, §§ 17551, 17553.) The Commission then determines ‘“whether a state mandate exists and, if so, the amount to be reimbursed.” (Kinlaw, supra, 54 Cal.3d at p. 332.) The Commission’s decision is reviewable by writ of mandate. (Gov. Code, § 17559.)
2. The test claims
The County and other Operators filed test claims with the Commission, seeking reimbursement for the Permit’s inspection and trash receptacle requirements. The Department, State Board, and Regional Board (collectively, the State) responded that the Operators were not entitled to reimbursement because each requirement was federally mandated.
The Department argued that the EPA had delegated its federal permitting authority to the Regional Board, which acted as an administrator for the EPA, ensuring the state’s program complied with the CWA. The Department acknowledged the Regional Board had discretion to set detailed permit conditions, but urged that the challenged conditions were required for the Permit to comply with federal law.
The State and Regional Boards argued somewhat differently. They contended the CWA required the Regional Board to impose specific permit [760]*760controls to reduce the discharge of pollutants to the “maximum extent practicable.” Thus, when the Regional Board determined the Permit’s conditions, those conditions were part of the federal mandate. The State and Regional Boards also argued that the challenged conditions were “animated” by EPA regulations. In support of the trash receptacle requirement, they relied on 40 Code of Federal Regulations part 122.26(d)(2)(iv)(A)(3).8 In support of the inspection requirements, they relied on 40 Code of Federal Regulations part 122.26(d)(2)(iv)(B)(l),9 (C)(1),10 and (D)(3).11
The Operators argued the conditions were not mandated by federal law, because nothing in the CWA or in the cited federal regulations required them to install trash receptacles or perform the required site inspections. They also submitted evidence showing that none of the challenged requirements were [761]*761contained in their previous permits issued by the Regional Board, nor were they imposed on other municipal storm sewer systems by the EPA.
As to the inspection requirements, the Operators argued that state law required the state and regional boards to regulate discharges of waste. This regulatory authority included the power to inspect facilities and sites. The Regional Board had used the Permit conditions to shift those inspection responsibilities to them. They also presented evidence that the Regional Board was required to inspect industrial facilities and construction sites for compliance with statewide permits issued by the State Board (see ante, p. 758, fns. 5, 6). They urged that the Regional Board had shifted that obligation to the Operators as well. Finally, the Operators submitted a declaration from a county employee indicating the Regional Board had offered to pay the County to inspect industrial facilities on behalf of the Regional Board, but revoked that offer after including the inspection requirement in the Permit.
The EPA submitted comments to the Commission indicating that the challenged Permit requirements were designed to reduce the discharge of pollutants to the “maximum extent practicable.” Thus, the EPA urged the requirements fell “within the scope” of federal regulations and other EPA guidance regarding stormwater management programs. The Bay Area Stormwater Management Agencies Association, the League of California Cities, and the California State Association of Counties submitted comments urging that the challenged requirements were state, rather than federal, mandates.
3. The commission’s decision
By a four-to-two vote, the Commission partially approved the test claims, concluding none of the challenged requirements were mandated by federal law. However, the Commission determined the Operators were not entitled to reimbursement for the inspection requirements because they had authority to levy fees to pay for the required inspections. Under Government Code section 17556, subdivision (d), the constitutional reimbursement requirement does not apply if the local government has the authority to levy fees or assessments sufficient to pay for the mandated program or service.
4. Petitions for writ of mandate
The State challenged the Commission’s determination that the requirements were state mandates. By cross-petition, the County and certain cities challenged the Commission’s finding that they could impose fees to pay for the inspections.
The trial court concluded that, because each requirement fell “within the maximum extent practicable standard,” they were federal mandates not [762]*762subject to reimbursement. It granted the State’s petition and ordered the Commission to issue a new statement of decision. The court did not reach the cross-claims relating to fee authority. Certain Operators appealed.12 The Court of Appeal affirmed, concluding as a matter of law that the trash receptacle and inspection requirements were federal mandates.
II. Discussion
A. Standard of Review
Courts review a decision of the Commission to determine whether it is supported by substantial evidence. (Gov. Code, § 17559.) Ordinarily, when the scope of review in the trial court is whether the administrative decision is supported by substantial evidence, the scope of review on appeal is the same. (County of Los Angeles v. Commission on State Mandates (1995) 32 Cal.App.4th 805, 814 [38 Cal.Rptr.2d 304] (County of Los Angeles)) However, the appellate court independently reviews conclusions as to the meaning and effect of constitutional and statutory provisions. (City of San Jose v. State of California (1996) 45 Cal.App.4th 1802, 1810 [53 Cal.Rptr.2d 521].) The question whether a statute or executive order imposes a mandate is a question of law. {Ibid.) Thus, we review the entire record before the Commission, which includes references to federal and state statutes and regulations, as well as evidence of other permits and the parties’ obligations under those permits, and independently determine whether it supports the Commission’s conclusion that the conditions here were not federal mandates. (Ibid.)
B. Analysis
The parties do not dispute here that each challenged requirement is a new program or higher level of service. The question here is whether the requirements were mandated by a federal law or regulation.
1. The federal mandate exception
Voters added article XIII B to the California Constitution in 1979. Also known as the “ ‘Gann limit,’ ” it “restricts the amounts state and local governments may appropriate and spend each year from the ‘proceeds of taxes.’ ” (City of Sacramento v. State of California (1990) 50 Cal.3d 51, 58-59 [266 Cal.Rptr. 139, 785 P.2d 522] (City of Sacramento).) “Article XIII B is to be distinguished from article XIII A, which was adopted as Proposition 13 at [763]*763the June 1978 election. Article XIIIA imposes a direct constitutional limit on state and local power to adopt and levy taxes. Articles XIII A and XIII B work in tandem, together restricting California governments’ power both to levy and to spend for public purposes.” {Id. at p. 59, fn. 1.)
The “concern which prompted the inclusion of section 6 in article XIII B was the perceived attempt by the state to enact legislation or adopt administrative orders creating programs to be administered by local agencies, thereby transferring to those agencies the fiscal responsibility for providing services which the state believed should be extended to the public.” (County of Los Angeles v. State of California (1987) 43 Cal.3d 46, 56 [233 Cal.Rptr. 38, 729 P.2d 202].) The reimbursement provision in section 6 was included in recognition of the fact “that articles XIII A and XIII B severely restrict the taxing and spending powers of local governments.” (County of San Diego v. State of California (1997) 15 Cal.4th 68, 81 [61 Cal.Rptr.2d 134, 931 R2d 312] (County of San Diego).) The purpose of section 6 is to prevent “the state from shifting financial responsibility for carrying out governmental functions to local agencies, which are ‘ill equipped’ to assume increased financial responsibilities because of the taxing and spending limitations that articles XIII A and XIII B impose.” (County of San Diego, at p. 81.) Thus, with certain exceptions, section 6 “requires the state ‘to pay for any new governmental programs, or for higher levels of service under existing programs, that it imposes upon local governmental agencies.’ ” (County of San Diego, at p. 81.)
As noted, reimbursement is not required if the statute or executive order imposes “a requirement that is mandated by a federal law or regulation,” unless the state mandate imposes costs that exceed the federal mandate. (Gov. Code, § 17556, subd. (c).) The question here is how to apply that exception when federal law requires a local agency to obtain a permit, authorizes the state to issue the permit, and provides the state discretion in determining which conditions are necessary to achieve a general standard established by federal law, and when state law allows the imposition of conditions that exceed the federal standard. Previous decisions of this court and the Courts of Appeal provide guidance.
In City of Sacramento, supra, 50 Cal.3d 51, this court addressed local governments’ reimbursement claims for the costs of extending unemployment insurance protection to their employees. (Id. at p. 59.) Since 1935, the applicable federal law had provided powerful incentives for states to implement their own unemployment insurance programs. Those incentives included federal subsidies and a substantial federal tax credit for all corporations in states with certified federal programs. (Id. at p. 58.) California had implemented such a program. (Ibid.) In 1976, Congressional legislation required [764]*764that unemployment insurance protection be extended to local government employees. {Ibid.) If a state failed to comply with that directive, it “faced [the] loss of the federal tax credit and administrative subsidy.” {Ibid.) The Legislature passed a law requiring local governments to participate in the state’s unemployment insurance program. {Ibid.)
Two local governments sought reimbursement for the costs of complying with that requirement. Opposing the claims, the state argued its action was compelled by federal law. This court agreed, reasoning that, if the state had “failed to conform its plan to new federal requirements as they arose, its businesses [would have] faced a new and serious penalty” of double taxation, which would have placed those businesses at a competitive disadvantage against businesses in states complying with federal law. (City of Sacramento, supra, 50 Cal.3d at p. 74.) Under those circumstances, we concluded that the “state simply did what was necessary to avoid certain and severe federal penalties upon its resident businesses.” (Ibid.) Because “[t]he alternatives were so far beyond the realm of practical reality that they left the state ‘without discretion’ to depart from federal standards,” we concluded “the state acted in response to a federal ‘mandate.’ ” (Ibid., italics added.)
County of Los Angeles, supra, 32 Cal.App.4th 805, involved a different kind of federal compulsion. In Gideon v. Wainwright (1963) 372 U.S. 335 [9 L.Ed.2d 799, 83 S.Ct. 792], the United States Supreme Court held that states were required by the federal Constitution to provide counsel to indigent criminal defendants. That requirement had been construed to include “the right to the use of any experts that will assist counsel in preparing a defense.” (County of Los Angeles, at p. 814.) The Legislature enacted Penal Code section 987.9, requiring local governments to provide indigent criminal defendants with experts for the preparation of their defense. (County of Los Angeles, at p. 811, fn. 3.) Los Angeles County sought reimbursement for the costs of complying with the statute. The state argued the statute’s requirements were mandated by federal law.
The state prevailed. The Court of Appeal reasoned that, even without Penal Code section 987.9, the county would have been “responsible for providing ancillary services” under binding Supreme Court precedent. (County of Los Angeles, supra, 32 Cal.App.4th at p. 815.) Penal Code section 987.9 merely codified an existing federal mandate. (County of Los Angeles, at p. 815.)
Hayes v. Commission on State Mandates (1992) 11 Cal.App.4th 1564 [15 Cal.Rptr.2d 547] (Hayes) provides a contrary example. Hayes involved the former federal Education of the Handicapped Act (EHA; 20 U.S.C. § 1401 et seq.). EHA was a “comprehensive measure designed to provide all handicapped children with basic educational opportunities.” (Hayes, at [765]*765p. 1594.) EHA required each state to adopt an implementation plan, and mandated “certain substantive and procedural requirements,” but left “primary responsibility for implementation to the state.” (Hayes, at p. 1594.)
Two local governments sought reimbursement for the costs of special education assessment hearings which were required under the state’s adopted plan. The state argued the requirements imposed under its plan were federally mandated. The Hayes court rejected that argument. Reviewing the historical development of special education law (Hayes, supra, 11 Cal.App.4th at pp. 1582-1592), the court concluded that, so far as the state was concerned, the requirements established by the EHA were federally mandated (Hayes, at p. 1592). However, that conclusion “mark[ed] the starting point rather than the end of [its] consideration.” (Ibid.) The court explained that, in determining whether federal law requires a specified function, like the assessment hearings, the focus of the inquiry is whether the “manner of implementation of the federal program was left to the true discretion of the state.” (Id. at p. 1593, italics added.) If the state “has adopted an implementing statute or regulation pursuant to the federal mandate,” and had “no ‘true choice’ ” as to the manner of implementation, the local government is not entitled to reimbursement. (Ibid.) If, on the other hand, “the manner of implementation of the federal program was left to the true discretion of the state,” the local government might be entitled to reimbursement. (Ibid.)
According to the Hayes court, the essential question is how the costs came to be imposed upon the agency required to bear them. “If the state freely chose to impose the costs upon the local agency as a means of implementing a federal program then the costs are the result of a reimbursable state mandate regardless whether the costs were imposed upon the state by the federal government.” (Hayes, supra, 11 Cal.App.4th at p. 1594.) Applying those principles, the court concluded that, to the extent “the state implemented the [EHA] by freely choosing to impose new programs or higher levels of service upon local school districts, the costs of such programs or higher levels of service are state mandated and subject to” reimbursement. (Ibid.)
From City of Sacramento, County of Los Angeles, and Hayes, we distill the following principle: If federal law compels the state to impose, or itself imposes, a requirement, that requirement is a federal mandate. On the other hand, if federal law gives the state discretion whether to impose a particular implementing requirement, and the state exercises its discretion to impose the requirement by virtue of a “true choice,” the requirement is not federally mandated.
Division of Occupational Safety & Health v. State Bd. of Control (1987) 189 Cal.App.3d 794 [234 Cal.Rptr. 661] (Division of Occupational Safety) is [766]*766instructive. The federal Occupational Safety and Health Act of 1970 (Fed. OSHA; 29 U.S.C. § 651 et seq.) preempted states from regulating matters covered by Fed. OSHA unless a state had adopted its own plan and gained federal approval. (Division of Occupational Safety, at p. 803.) No state was obligated to adopt its own plan. But, if a state did so, the plan had to include standards at least as effective as Fed. OSHA’s and extend those standards to state and local employees. California adopted its own plan, which was federally approved. The state then issued a regulation that, according to local fire districts, required them to maintain three-person firefighting teams. Previously, they had been permitted to maintain two-person teams. (Division of Occupational Safety, at pp. 798-799.) The local fire districts sought reimbursement for the increased level of service. The state opposed, arguing the requirement was mandated by federal law.
The court agreed with the fire districts. As the court explained, a Fed. OSHA regulation arguably required the maintenance of three-person firefighting teams. (Division of Occupational Safety, supra, 189 Cal.App.3d at p. 802.) However, that federal regulation specifically excluded local fire districts. (Id. at p. 803.) Had the state elected to be governed by Fed. OSHA standards, that exclusion would have allowed those fire districts to maintain two-person teams. (Division of Occupational Safely, at p. 803.) The conditions for approval of the state’s plan required effective enforcement and coverage of public employees. But those conditions did not make the costs of complying with the state regulation federally mandated. ‘“[T]he initial decision to establish ... a federally approved [local] plan is an option which the state exercises freely.” (Ibid.) In other words, the state was not “compelled to . . . extend jurisdiction over occupational safety to local governmental employers,” which would have otherwise fallen under a federal exclusion. (Ibid.) Because the state ‘“was not required to promulgate [the state regulation] to comply with federal law, the exemption for federally mandated costs does not apply.” (Id. at p. 804.)13
San Diego Unified School Dist. v. Commission on State Mandates (2004) 33 Cal.4th 859 [16 Cal.Rptr.3d 466, 94 P.3d 589] (San Diego Unified) provides another example. In Goss v. Lopez (1975) 419 U.S. 565 [42 L.Ed.2d 725, 95 S.Ct. 729], the United States Supreme Court held that if a school principal chose to recommend a student for expulsion, federal due process principles required the school district to give that student a hearing. Education Code section 48918 provided for expulsion hearings. (San Diego Unified, at p. 868.) Under Education Code section 48915, a school principal had [767]*767discretion to recommend expulsion under certain circumstances, but was compelled to recommend expulsion for a student who possessed a firearm. (San Diego Unified, at p. 869.) Federal law at the time did not require expulsion for a student who brought a gun to school. (Id. at p. 883.)
The school district argued it was entitled to reimbursement of all expulsion hearing costs. This court drew a distinction between discretionary and mandatory expulsions. We concluded the costs of hearings for discretionary expulsions flowed from a federal mandate. (San Diego Unified, supra, 33 Cal.4th at pp. 884-890.)14 We declined, however, to extend that rule to the costs related to mandatory expulsions. Because it was state law that required an expulsion recommendation for firearm possession, all hearing costs triggered by the mandatory expulsion provision were reimbursable state-mandated expenses. (San Diego Unified, at pp. 881-883.) As was the case in Hayes, the key factor was how the costs came to be imposed on the enhty that was required to bear them. The school principal could avoid the cost of a federally mandated hearing by choosing not to recommend an expulsion. But, when a state statute required an expulsion recommendation, the attendant hearing costs did not flow from a federal mandate. (San Diego Unified, supra, 33 Cal.4th at p. 881.)
2. Application
Review of the Commission’s decision requires a determination as to whether federal statutory, administrative, or case law imposed, or compelled the Regional Board to impose, the challenged requirements on the Operators.
It is clear federal law did not compel the Regional Board to impose these particular requirements. There was no evidence the state was compelled to administer its own permitting system rather than allowing the EPA do so under the CWA. (33 U.S.C. § 1342(a).) In this respect, the case is similar to Division of Occupational Safety, supra, 189 Cal.App.3d 794. Here, as in that case, the State chose to administer its own program, finding it was “in the interest of the people of the state, in order to avoid direct regulation by the federal government of persons already subject to regulation” under state law. (Wat. Code, § 13370, subd. (c), italics added.) Moreover, the Regional Board was not required by federal law to impose any specific permit conditions. The federal CWA broadly directed the Board to issue permits with conditions designed to reduce pollutant discharges to the maximum extent practicable. But the EPA’s regulahons gave the Board discretion to determine which [768]*768specific controls were necessary to meet that standard. (40 C.F.R. § 122.26(d)(2)(iv).) This case is distinguishable from City of Sacramento, supra, 50 Cal.3d 51, where the state risked the loss of subsidies and tax credits for all its resident businesses if it failed to comply with federal legislation. Here, the State was not compelled by federal law to impose any particular requirement. Instead, as in Hayes, supra, 11 Cal.App.4th 1564, the Regional Board had discretion to fashion requirements which it determined would meet the CWA’s maximum extent prachcable standard.
The State argues the Commission failed to account for the flexibility in the CWA’s regulatory scheme, which conferred discretion on the State and regional boards in deciding what conditions were necessary to comply with the CWA. In exercising that discretion, those agencies were required to rely on their scientific, technical, and experiential knowledge. Thus, the State contends the Permit itself is the best indication of what requirements would have been imposed by the EPA if the Regional Board had not done so, and the Commission should have deferred to the Board’s determination of what conditions federal law required.
We disagree that the Permit itself demonstrates what conditions would have been imposed had the EPA granted the Permit. In issuing the Permit, the Regional Board was implementing both state and federal law and was authorized to include conditions more exacting than federal law required. (City of Burbank, supra, 35 Cal.4th at pp. 627-628.) It is simply not the case that, because a condition was in the Permit, it was, ipso facto, required by federal law.
We also disagree that the Commission should have deferred to the Regional Board’s conclusion that the challenged requirements were federally mandated. That determination is largely a question of law. Had the Regional Board found, when imposing the disputed Permit conditions, that those conditions were the only means by which the maximum extent prachcable standard could be implemented, deference to the Board’s experhse in reaching that finding would be appropriate. The Board’s legal authority to administer the CWA and its technical experience in water quality control would call on sister agencies as well as courts to defer to that finding.15 The State, however, provides no authority for the proposition that, absent such a finding, the Commission should defer to a state agency as to whether requirements were state or federally mandated. Certainly, in a trial court action challenging a regional Board’s authority to impose specific permit conditions, the Board’s findings regarding what conditions satisfied the federal standard would be entitled to deference. (See, e.g., City of Rancho Cucamonga v. Regional Water Quality Control Bd. (2006) 135 Cal.App.4th 1377, 1384 [38 Cal.Rptr.3d 450], [769]*769citing Fukuda v. City of Angels (1999) 20 Cal.4th 805, 817-818 [85 Cal.Rptr.2d 696, 977 P.2d 693].) Resolution of those questions would bring into play the particular technical expertise possessed by members of the regional board. In those circumstances, the party challenging the board’s decision would have the burden of demonstrating its findings were not supported by substantial evidence or that the board otherwise abused its discretion. (Rancho Cucamonga, at p. 1387; Building Industry, supra, 124 Cal.App.4th at pp. 888-889.)
Reimbursement proceedings before the Commission are different. The question here was not whether the Regional Board had authority to impose the challenged requirements. It did. The narrow question here was who will pay for them. In answering that legal question, the Commission applied California’s constitutional, statutory, and common law to the single issue of reimbursement. In the context of these proceedings, the State has the burden to show the challenged conditions were mandated by federal law.
Section 6 establishes a general rule requiring reimbursement of all state-mandated costs. Government Code section 17556, subdivision (c), codifies an exception to that rule. Typically, the party claiming the applicability of an exception bears the burden of demonstrating that it applies. (See Simpson Strong-Tie Co., Inc. v. Gore (2010) 49 Cal.4th 12, 23 [109 Cal.Rptr.3d 329, 230 P.3d 1117]; see also Long Beach Police Officers Assn. v. City of Long Beach (2014) 59 Cal.4th 59, 67 [172 Cal.Rptr.3d 56, 325 P.3d 460].) Here, the State must explain why federal law mandated these requirements, rather than forcing the Operators to prove the opposite. The State’s proposed rule, requiring the Commission to defer to the Regional Board, would leave the Commission with no role to play on the narrow question of who must pay. Such a result would fail to honor the Legislature’s intent in creating the Commission.
Moreover, the policies supporting article XIII B of the California Constitution and section 6 would be undermined if the Commission were required to defer to the Regional Board on the federal mandate question. The central purpose of article XIII B is to rein in local government spending. (City of Sacramento, supra, 50 Cal.3d at pp. 58-59.) The purpose of section 6 is to protect local governments from state attempts to impose or shift the costs of new programs or increased levels of service by entitling local governments to reimbursement. (County of San Diego, supra, 15 Cal.4th at p. 81.) Placing the burden on the State to demonstrate that a requirement is federally mandated, and thus excepted from reimbursement, serves those purposes.
Applying the standard of review described above, we evaluate the entire record and independently review the Commission’s determination the challenged conditions were not federal mandates. We conclude the Commission was correct. These Permit conditions were not federally mandated.
[770]*770(a) The inspection requirements
Neither the CWA’s “maximum extent practicable” provision nor the EPA regulations on which the State relies expressly required the Operators to inspect these particular facilities or construction sites. The CWA makes no mention of inspections. (33 U.S.C. § 1342(p)(3)(B)(iii).) The regulations required the Operators to include in their permit application a description of priorities and procedures for inspecting certain industrial facilities and construction sites, but suggested that the Operators would have discretion in selecting which facilities to inspect. (See 40 C.F.R. § 122.26(d)(2)(iv)(C)(l).) The regulations do not mention commercial facility inspections at all.
Further, as the Operators explained, state law made the Regional Board responsible for regulating discharges of waste within its jurisdiction. (Wat. Code, §§ 13260, 13263.) This regulatory authority included the power to “inspect the facilities of any person to ascertain whether . . . waste discharge requirements are being complied with.” (Wat. Code, § 13267, subd. (c).) Thus, state law imposed an overarching mandate that the Regional Board inspect the facilities and sites.
In addition, federal law and practice required the Regional Board to inspect all industrial facilities and construction sites. Under the CWA, the State Board, as an issuer of NPDES permits, was required to issue permits for stormwater discharges “associated with industrial activity.” (33 U.S.C. § 1342(p)(3)(A).) The term “industrial activity” includes “construction activity.” (40 C.F.R. § 122.26(b)(14)(x).) The Operators submitted evidence that the State Board had satisfied its obligation by issuing a general industrial activity stormwater permit and a general construction activity stormwater permit. Those statewide permits imposed controls designed to reduce pollutant discharges from industrial facilities and construction sites. Under the CWA, those facilities and sites could operate under the statewide permits rather than obtaining site-specific pollutant discharge permits.
The Operators showed that, in those statewide permits, the State Board had placed responsibility for inspecting facilities and sites on the Regional Board. The Operators submitted letters from the EPA indicating the State and regional boards were responsible for enforcing the terms of the statewide permits. The Operators also noted the State Board was authorized to charge a fee to facilities and sites that subscribed to the statewide permits (Wat. Code, § 13260, subd. (d)), and that a portion of that fee was earmarked to pay the Regional Board for “inspection and regulatory compliance issues” (Wat. Code, § 13260, subd. (d)(2)(B)(iii)). Finally, there was evidence the Regional Board offered to pay the County to inspect industrial facilities. There would have been little reason to make that offer if federal law required the County to inspect those facilities.
[771]*771This record demonstrates that the Regional Board had primary responsibility for inspecting these facilities and sites. It shifted that responsibility to the Operators by imposing these Permit conditions. The reasoning of Hayes, supra, 11 Cal.App.4th 1564, provides guidance. There, the EHA required the state to provide certain services to special education students, but gave the state discretion in implementing the federal law. (Hayes, at p. 1594.) The state exercised its “true discretion” by selecting the specific requirements it imposed on local governments. As a result, the Hayes court held the costs incurred by the local governments were state-mandated costs. (Ibid.) Here, state and federal law required the Regional Board to conduct inspections. The Regional Board exercised its discretion under the CWA, and shifted that obligation to the Operators. That the Regional Board did so while exercising its permitting authority under the CWA does not change the nature of the Regional Board’s action under section 6. Under the reasoning of Hayes, the inspection requirements were not federal mandates.
The State argues the inspection requirements were federally mandated because the CWA required the Regional Board to impose permit controls, and the EPA regulations contemplated that some kind of operator inspections would be required. That the EPA regulations contemplated some form of inspections, however, does not mean that federal law required the scope and detail of inspections required by the Permit conditions.16 As explained, the evidence before the Commission showed the opposite to be true.
(b) The trash receptacle requirement
The Commission concluded the trash receptacle requirement was not a federal mandate because neither the CWA nor the regulation cited by the State explicitly required the installation and maintenance of trash receptacles. The State contends the requirement was mandated by the CWA and by the EPA regulation that directed the Operators to include in their application a “description of practices for operating and maintaining public streets, roads and highways and procedures for reducing the impact on receiving waters of discharges from municipal storm sewer systems.” (40 C.ER. § 122.26(d)(2)(iv)(A)(3).)
The Commission’s determination was supported by the record. While the Operators were required to include a description of practices and procedures in their permit application, the issuing agency has discretion whether to make [772]*772those practices conditions of the permit. (40 C.F.R. § 122.26(d)(2)(iv).) No regulation cited by the State required trash receptacles at transit stops. In addition, there was evidence that the EPA had issued permits to other municipal storm sewer systems in Anchorage, Boise, Boston, Albuquerque, and Washington, D.C., that did not require trash receptacles at transit stops. The fact the EPA itself had issued permits in other cities, but did not include the trash receptacle condition, undermines the argument that the requirement was federally mandated.
(c) Conclusion
Although we have upheld the Commission’s determination on the federal mandate question, the State raised other arguments in its writ petition. Further, the issues presented in the Operators’ cross-petition were not addressed by either the trial court or the Court of Appeal. We remand the matter so those issues can be addressed in the first instance.
III. Disposition
We reverse the judgment of the Court of Appeal and remand for further proceedings consistent with our opinion.
Cantil-Sakauye, C. J., Werdegar, J., and Chin, J., concurred.