In the Matter of the Decision to Deny the Petitions for a Contested Case Hearing and to Submit the Draft Little Rock Creek Dissolved Oxygen, Nitrate, Temperature, and Fish Bioassessment Total Maximum Daily Load Study to the U.S. Environmental Protection Agency for Approval. ( 2016 )


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  •                            This opinion will be unpublished and
    may not be cited except as provided by
    Minn. Stat. § 480A.08, subd. 3 (2014).
    STATE OF MINNESOTA
    IN COURT OF APPEALS
    A16-0123
    In the Matter of the Decision
    to Deny the Petitions for a Contested Case Hearing and
    to Submit the Draft Little Rock Creek Dissolved Oxygen, Nitrate, Temperature,
    and Fish Bioassessment Total Maximum Daily Load Study to the
    U.S. Environmental Protection Agency for Approval.
    Filed November 28, 2016
    Affirmed
    Reilly, Judge
    Minnesota Pollution Control Agency
    Matthew C. Berger, Dean M. Zimmerli, Gislason & Hunter LLP, New Ulm, Minnesota
    (for relators Duane Kroll, et al.)
    Lori Swanson, Attorney General, Ann E. Cohen, Assistant Attorney General, St. Paul,
    Minnesota (for respondent Minnesota Pollution Control Agency)
    Considered and decided by Reilly, Presiding Judge; Halbrooks, Judge; and Johnson,
    Judge.
    UNPUBLISHED OPINION
    REILLY, Judge
    Relator-landowners petitioned for certiorari review of the Minnesota Pollution
    Control Agency’s (the MPCA) decision to submit a Total Maximum Daily Load (TMDL)
    study of the Little Rock Creek watershed area to the Environmental Protection Agency (the
    EPA) for approval pursuant to the federal Clean Water Act, 
    33 U.S.C. § 1313
    (d) (2012)
    (the CWA). The MPCA asserts that (1) relators lack standing to pursue this certiorari
    appeal; (2) the MPCA’s decision is supported by the record; and (3) relators are not entitled
    to a contested-case hearing. We determine that relators have standing through a legislative
    enactment granting standing. However, because relators have not met their burden of
    demonstrating that the MPCA’s decision was unsupported by the record and the MPCA
    did not err by denying a contested-case hearing, we affirm.
    FACTS
    I.     Parties
    Relators are residents, landowners, and farmers near the Little Rock Creek
    watershed. The MPCA is the state agency charged with enforcing the CWA and has the
    authority to “administer and enforce all laws relating to the pollution of any of the waters
    of the state.” 
    Minn. Stat. §115.03
    , subd. 1(a) (2014); Minn. Envtl. Sci. & Econ. Review Bd.
    v. Minn. Pollution Control Agency, 
    870 N.W.2d 97
    , 99 (Minn. App. 2015).
    II.    Statutory and Regulatory Framework
    The stated objective of the CWA is “to restore and maintain the chemical, physical,
    and biological integrity of the Nation’s waters.” 
    33 U.S.C. § 1251
    (a) (2012). To attain
    this objective, the CWA provides two methods for controlling water pollution: effluent
    limitations and water quality standards. Arkansas v. Oklahoma, 
    503 U.S. 91
    , 101, 
    112 S. Ct. 1046
    , 1054 (1992).       “Effluent limitations” restrict the “quantities, rates, and
    concentrations of chemical, physical, biological, and other constituents” discharged from
    point sources into waterways. Id.; 
    33 U.S.C. § 1362
    (11) (2012). “Point sources” are “any
    discernible, confined and discrete conveyance” from which pollutants are or may be
    discharged including pipes, ditches, tunnels, wells, and other containers. 33 U.S.C.
    2
    §1362(14) (2014). Unlike point source discharges, “nonpoint-source discharges” are not
    explicitly defined by the CWA, but have been described as “nothing more than a water
    pollution problem not involving a discharge from a point source.” Defs. of Wildlife v. U.S.
    Envtl. Prot. Agency, 
    415 F.3d 1121
    , 1124 (10th Cir. 2005) (quotation omitted).1
    “Water quality standards set the permissible level of pollution in a specific body of
    water without direct regulation of the individual sources of pollution.” City of Arcadia v.
    U.S. Envtl. Prot. Agency, 
    411 F.3d 1103
    , 1105 (9th Cir. 2005). The CWA requires each
    state to adopt water quality standards for bodies of water within the state’s boundaries that
    “establish the desired condition of a body of water.” In re Cities of Annandale & Maple
    Lake NPDES/SDS Permit, 
    731 N.W.2d 502
    , 510 (Minn. 2007); 
    33 U.S.C. § 1313
    (a)-(c).
    After establishing its water quality standards, a state is required by the CWA to identify
    “impaired” bodies of water within its boundaries that fail to meet those standards. 
    33 U.S.C. § 1313
    (d)(1)(a); 
    40 C.F.R. § 130.7
    (b). This list of substandard waters is known as
    the “§ 303(d) list” or the “impaired waters” list. Thomas v. Jackson, 
    581 F.3d 658
    , 661,
    667 (8th Cir. 2009). When creating a § 303(d) list, a state “must assemble and evaluate all
    existing and readily available water quality-related data and information.” Id. at 661 (citing
    
    40 C.F.R. § 130.7
    (b)(5)).
    For each impaired body of water on the § 303(d) list, the state must establish a
    TMDL for each pollutant the water can sustain without exceeding water quality standards.
    1
    A number of federal courts have rendered decisions arising out of the federal Clean Water
    Act, 
    33 U.S.C. § 1313
    (d), and we find the reasoning in these federal decisions to be
    persuasive authority in the present case.
    3
    
    Id. at 662
    ; 
    33 U.S.C. § 1313
    (d)(1)(C) (articulating this requirement). A TMDL is defined
    as:
    the sum of the pollutant load allocations for all sources of the
    pollutant, including a wasteload allocation for point sources, a
    load allocation for nonpoint sources and natural background,
    an allocation for future growth of point and nonpoint sources,
    and a margin of safety to account for uncertainty about the
    relationship between pollutant loads and the quality of the
    receiving surface water.
    Minn. Stat. § 114D.15, subd. 10 (2014) (defining TMDL as “a scientific study that contains
    a calculation of the maximum amount of a pollutant that may be introduced into a surface
    water and still ensure that applicable water quality standards for that water are restored and
    maintained”); 
    40 C.F.R. § 130.2
    (g)-(i) (defining load allocation, wasteload allocation, and
    TMDL allocation); 
    33 U.S.C. § 1362
    (6) (defining “pollutant” as “dredged spoil, solid
    waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes,
    biological materials, radioactive materials, heat, wrecked or discarded equipment, rock,
    sand, cellar dirt and industrial, municipal, and agricultural waste discharged into water”).
    The state must submit its § 303(d) list and the TMDL to the EPA for approval. 
    33 U.S.C. § 1313
    (d)(2). The EPA will either approve or disapprove the state’s § 303(d) list within
    30 days of submission and, if the EPA disapproves a state’s § 303(d) list, it will establish
    its own list within 30 days of the date of disapproval. 
    40 C.F.R. § 130.7
    (d)(2).
    III.    Factual and Procedural Background
    Little Rock Creek is a DNR-designated trout stream in central Minnesota. The land-
    use in the watershed area consists of approximately 50% crops, 14% woodland, 22% grass
    4
    and pasture, 13% water and wetlands, and less than 1% residential development. The area
    is considered “highly altered by human influenced agricultural land uses.”
    In 2002, the MPCA proposed placing Little Rock Creek on the § 303(d) list for lack
    of coldwater fish assemblage and “due to a biological impairment as indicated by a poor
    warmwater fish . . . score” on the Indices of Biological Integrity. The EPA approved this
    designation in 2003. During the 2006 assessment cycle, Little Rock Creek was removed
    from the § 303(d) list when an examination revealed that it was designated as a Class 2A
    coldwater stream and, at that time, the MPCA lacked the tools to properly assess the
    biology of coldwater streams. In 2010, the MPCA again placed Little Rock Creek on the
    § 303(d) list because it failed to meet water quality standards for dissolved oxygen and
    nutrients, and due to the “lack of a coldwater assemblage.” The EPA approved the list in
    2012.
    Following Little Rock Creek’s initial placement on the § 303(d) list in 2002, the
    MPCA began working with the Benton County Soil and Water Conservation District and
    the Morrison County Soil and Water Conservation District (the SWCDs) on the Little Rock
    Creek TMDL, using a three-phased approach.
    In phase I, the MPCA collected and organized existing data and developed a list of
    potential stressors on the Little Rock Creek watershed area.
    In phase II, the MPCA, in conjunction with the SWCDs, produced a Stressor
    Identification Report to “identify stressors contributing to [the] lack of cold water fish
    assemblage in Little Rock Creek.” “Stressors” are “[the] specific physical and/or chemical
    factors that . . . caus[e] [a] biological impairment.” The MPCA invited local, state, and
    5
    federal agencies, interest groups, organizations, and citizens to participate in the process
    and provide input into the development of the TMDL. The Stressor Identification Report
    was published in 2009 and included watershed data, stakeholder meeting comments,
    technical group meetings and coordination information, causal analysis, and stressor
    identification documentation, “contain[ing] the complete stressor identification for lack of
    cold water fish assemblage.” The study “used a variety of methods to evaluate the current
    loading and contributions from the various pollutant sources,” along with “the allowable
    pollutant loading capacity of the impaired reaches.” The report concluded that “it is
    probable that altered flow, temperature, sediment, dissolved oxygen, and nitrates may be
    causing a biological impairment in Little Rock Creek.”
    Following the release of the Stressor Identification Report, the MPCA developed a
    draft TMDL work plan in phase III of the project for “temperature, bedded sentiment,
    nitrates, and dissolved oxygen, by calculating the total pollutant load with reference to flow
    as [a] source of impairment.” The specific objective of the TMDL was to “determine the
    type and degree of pollutant source reductions needed to achieve the water quality
    standards . . . for drinking water . . . [and] temperature” in the water. The TMDL advised
    that in order to satisfy water quality standards, Little Rock Creek required a 52% reduction
    in total oxygen demand; a 19-47% reduction in the nitrate load, depending on flow
    conditions; and a 1% reduction in thermal loading.              The TMDL developed an
    implementation plan to address the water’s stressors and their sources. The TMDL stated
    that the “ideal combination” of implementation strategies and best management practices
    would include: (1) reducing groundwater use, which could include limiting total
    6
    appropriations, improving irrigation efficiency, scheduling and technologies, and
    identifying alternative sources; (2) reducing nutrient and organic constituents; and
    (3) creating “more of a free flowing system” to improve connectivity and temperature
    issues.
    The MPCA submitted its draft TMDL to the EPA in November 2012 for preliminary
    review. The EPA provided comments on the TMDL, which the MPCA incorporated. The
    MPCA held a public comment period and posted a draft of the study on its website. The
    MPCA received, and responded to, nine timely written comments.
    The MPCA’s approval of a TMDL is a final decision of the agency and is subject
    to the contested-case hearing procedures of the Administrative Procedure Act. Minn. Stat.
    § 114D.25, subd. 2 (2014); 
    Minn. Stat. Ann. § 14.57
    (a) (2014). The MPCA received two
    timely petitions for a contested-case hearing on Little Rock Creek’s TMDL study. The
    petitions are largely identical and raised issues relating to “(1) the natural backgrounds in
    load allocations; and (2) the effect of reducing nitrate loading on bio-accumulative toxin
    methyl-mercury and for blue-green algae.” The MPCA determined that “the petitions do
    not meet the threshold petition content requirements by stating reasons to hold a [contested-
    case hearing] and by stating issues to be addressed and specific relief requested.” The
    MPCA concluded that “the issues raised . . . do not meet the requirements for granting a
    [contested-case hearing]” and denied the petitions.
    This certiorari appeal follows.
    7
    DECISION
    I.    Relators have standing to pursue this appeal.
    a. Standard of Review
    “Standing is a legal requirement that a party have a sufficient stake in a justiciable
    controversy to seek relief from a court.” McCaughtry v. City of Red Wing, 
    808 N.W.2d 331
    , 338 (Minn. 2011) (quotation and citation omitted). Standing is conferred upon a party
    in one of two ways: either the plaintiff has suffered an injury-in-fact or the plaintiff
    maintains a statutory right to sue. Nash v. Wollan, 
    656 N.W.2d 585
    , 588 (Minn. App.
    2003). “The purpose of the standing requirement is to ensure that issues before the court
    will be vigorously and adequately presented.” State ex rel. Hatch v. Allina Health Sys.,
    
    679 N.W.2d 400
    , 404 (Minn. App. 2004) (quotations omitted). Because standing is a
    jurisdictional issue, we evaluate standing determinations de novo. In re Custody of D.T.R.,
    
    796 N.W.2d 509
    , 512 (Minn. 2011).
    b. A legislative enactment grants relators standing.
    The MPCA challenges relators’ standing to pursue this appeal. Standing may be
    acquired “when a party is the beneficiary of some legislative enactment granting standing.”
    Citizens for a Balanced City v. Plymouth Congregational Church, 
    672 N.W.2d 13
    , 18
    (Minn. App. 2003) (quotation omitted). Minnesota Statutes section 114D.25, subdivision
    2, provides that “[t]he approval of a TMDL by the [MPCA] is a final decision of the agency
    for purposes of section 115.05, and is subject to the contested case procedures of sections
    14.57 to 14.62.” Minnesota Statutes section 115.05, subdivision 11 (2014), provides that
    8
    “[a]ny person aggrieved by any final decision of the [MPCA] may obtain judicial review
    thereof pursuant to sections 14.63 to 14.69.”
    The MPCA argues that relators are not “aggrieved” parties within the meaning of
    section 115.05. An “aggrieved person” is
    one who is injuriously or adversely affected by the judgment
    or decree when it operates on his rights of property or bears
    directly upon his personal interest. The word “aggrieved”
    refers to a substantial grievance, a denial of some personal or
    property right, or the imposition on a party of a burden or
    obligation.
    In re Application by City of Rochester for Adjustment of Serv. Area Boundaries, 
    524 N.W.2d 540
    , 542 n.1 (Minn. App. 1994) (citing In re Getsug, 
    290 Minn. 110
    , 114, 
    186 N.W.2d 686
    , 689 (1971)).
    Relators argue that they are aggrieved parties because they will be affected by the
    pollutant load limits imposed as a result of the Little Rock Creek TMDL, including lower
    property values and compliance costs. The MPCA argues that relators’ claims are too
    speculative and remote at this stage because the draft TMDL was merely “one step in a
    long chain” that may eventually cause relators “unspecified injuries.” See, e.g., Missouri
    Soybean Ass’n v. U.S. E.P.A., 
    289 F.3d 509
    , 513 (8th Cir. 2002) (dismissing case on
    jurisdictional grounds where appellants challenged the EPA’s approval of Missouri’s
    § 303(d) list because appellants’ claims of potential harm were too remote).
    We previously rejected a similar argument. In Minn. Envtl. Sci. & Econ. Review
    Bd., municipalities, public-utilities commissions, sanitary sewer districts, and farmers who
    were potentially affected by changes in clean-water rules sought declaratory judgment in a
    9
    pre-enforcement challenge to water quality standards promulgated by the MPCA. 870
    N.W.2d at 98-99. The MPCA argued that petitioners lacked standing because they
    “fail[ed] to specify any specific rights which [were] currently affected” and their potential
    harms were “too tenuous and rel[ied] on too many indeterminate assumptions” to establish
    standing. Id. at 100. We disagreed and determined that petitioners had standing to bring
    an action for a pre-enforcement declaratory judgment. Id. at 100-01 (stating that petitioners
    were among “the class of persons who would be affected” by a change in water quality
    standards and had a “more particularized interest” in the outcome of the decision).
    The Third Circuit Court of Appeals also determined that standing existed in a similar
    case. In Am. Farm Bureau Fed’n v. U.S. E.P.A., the EPA published the TMDL of
    pollutants nitrogen, phosphorous, and sediment that could be released into Chesapeake
    Bay. 
    792 F.3d 281
     (3d Cir. 2015), cert. denied sub nom. Am. Farm Bureau Fed’n v. E.P.A.,
    
    136 S. Ct. 1246
     (2016). Appellants were trade associations with members who would be
    affected by implementation of the TMDL. 
    Id. at 287
    . The appellate court raised the issue
    of standing sua sponte. 
    Id. at 292
    . The court acknowledged that there was “a plausible
    argument that [appellants’] injury is insufficiently particularized and too speculative,” as it
    was unclear “precisely what form new regulations will take.” 
    Id. at 293
    . However, the
    court also recognized that appellants would “incur compliance costs when the TMDL is
    implemented and enforcement mechanisms are put in place,” and determined that
    appellants had standing to challenge the EPA’s approval of the TMDL. 
    Id. at 292-94
    .
    Because relators stand to be adversely affected by a final decision from the MPCA
    which bears directly upon their personal interest, we determine that relators fit within the
    10
    definition of an “aggrieved party” and have statutory standing to challenge the MPCA’s
    action.2
    II.    The MPCA’s decision was supported by the factual record and by
    controlling federal and state law.
    a. Standard of Review
    The MPCA’s approval of a TMDL is a “final decision of the agency for purposes
    of section 115.05.” Minn. Stat. § 114D.25, subd. 2. We review a final decision of the
    MPCA under the Minnesota Administrative Procedures Act, 
    Minn. Stat. §§ 14.63
    -.69
    (2014). 
    Minn. Stat. § 115.05
    , subd. 11. We will affirm the MPCA’s decision unless its
    findings, inferences, conclusions or decisions are affected by an error of law, unsupported
    by substantial evidence in view of the entire record as submitted, or are arbitrary and
    capricious. 
    Minn. Stat. § 14.69
    (b)-(f) (2014). We afford the decision of an administrative
    agency “a presumption of correctness” and defer to the agency’s expertise. In re N. Dakota
    Pipeline Co. LLC, 
    869 N.W.2d 693
    , 696 (Minn. App. 2015), review denied (Minn. Dec. 15,
    2015) (citation omitted). We defer to the agency’s decision as long as it is reasonable and
    supported by substantial evidence, and we will not replace the agency’s findings with our
    own. In re Rocheleau, 
    686 N.W.2d 882
    , 891 (Minn. App. 2004), review denied (Minn.
    Dec. 22, 2004). However, we are not bound by an agency’s rulings on matters of law and
    we review legal issues de novo. Cable Commc’ns Bd. v. Nor-west Cable Commc’ns P’ship,
    
    356 N.W.2d 658
    , 668-69 (Minn. 1984). “On appeal, the party challenging the agency’s
    2
    The MPCA also challenges whether relators have injury-in-fact standing. Because we
    determine that relators may assert a claim as aggrieved persons, we do not reach this
    argument.
    11
    decision [bears] the burden of proof.” In re Reichmann Land & Cattle, LLP, 
    847 N.W.2d 42
    , 46 (Minn. App. 2014), aff’d, 
    867 N.W.2d 502
     (Minn. 2015).
    b. The MPCA’s approval of the TMDL without a separate
    determination of “natural background” sources was neither an error
    of law nor arbitrary and capricious.
    EPA regulations define the TMDL for a pollutant as the sum of (1) the “wasteload
    allocation” for point source pollution; (2) the “load allocation” for nonpoint source or
    natural background pollution; and (3) a margin of safety. See 
    40 C.F.R. § 130.2
    (g)-(i);
    Minn. Stat. § 114D.15, subd. 10. “Natural background” includes those characteristics of a
    body of water “resulting from the multiplicity of factors in nature, including climate and
    ecosystem dynamics, that affect the physical, chemical, or biological conditions in a water
    body, but does not include measurable and distinguishable pollution that is attributable to
    human activity or influence.” Minn. Stat. § 114D.15, subd. 10.
    In its report to the EPA, the MPCA explained its methodology for arriving at load
    allocations, wasteload allocations, and margins of safety.3 The MPCA attributed zero
    discharge to point source categories such as wastewater treatment facilities, concentrated
    animal feeding operations, construction activities, and municipal and industrial stormwater
    sources. The MPCA attributed less than one percent to construction and industrial
    3
    “Wasteload allocation” is “[t]he portion of a receiving water’s loading capacity that is
    allocated to one of its existing or future point sources of pollution.” 
    40 C.F.R. § 130.2
    (h).
    “Load allocation” is “[t]he portion of a receiving water’s loading capacity that is attributed
    either to one of its existing or future nonpoint sources of pollution or to natural background
    sources.” 
    Id.,
     (g). Load allocations are “best estimates of the loading” and range “from
    reasonably accurate estimates to gross allotments, depending on the availability of data and
    appropriate techniques for predicting the loading.” 
    Id.
    12
    stormwater, and applied a ten-percent margin of safety “to account for uncertainty” in the
    allocation. The remaining 89.9% was attributed to “nonpoint pollution sources” and
    “natural background sources.”
    Relators argue that the MPCA failed to separately distinguish the pollutant loads
    attributable to the “natural background” of Little Rock Creek from those attributable to
    nonpoint source loads. “Wherever possible, natural and nonpoint source loads should be
    distinguished.” 
    40 C.F.R. § 130.2
    (g). The MPCA acknowledges that the TMDL did not
    include a separate load allocation for natural background sources, but notes that “nearly
    the entire pollutant loading to Little Rock Creek is from nonpoint sources and natural
    background, and current research is not sufficient to differentiate between nonpoint and
    natural background sources of pollutants.” Our review of the record supports the MPCA’s
    assertion that “consideration of natural background enter[ed] into essentially every phase
    of MPCA water quality programs.” By way of example, the Stressor Identification Report
    reveals that the MPCA considered “physical,” “chemical,” “biological,” and “other”
    stressors in the Little Rock Creek watershed, and eliminated physical stressors such as
    “[e]levation, habitat variety, in-stream habitat, land use, riparian zone, warm-water vs.
    cold-water environments, lakebed sentiment, and wetlands/drainage” because such natural
    background sources “were not deemed to be primary causes of impairment based on the
    group’s professional judgment.” Instead, the MPCA determined that the Little Rock Creek
    watershed area “is highly altered by human influenced agricultural land uses.”
    The record supports the conclusion that the MPCA gathered and considered natural
    background sources but did not assign a separate load allocation to those sources due to
    13
    their marginal impact on Little Rock Creek’s overall water quality. This determination is
    consistent with Sierra Club, N. Star Chapter v. Browner, 
    843 F. Supp. 1304
     (D. Minn.
    1993).     The Sierra Club court recognized that the “plain language” of clean water
    regulations requires consideration of “both point, nonpoint, and natural sources” of
    pollutants in the water. 
    Id. at 1313
    . In that case, the court found “no evidence” that the
    MPCA failed to consider nonpoint and natural sources of pollution when it developed the
    TMDL, and noted that the TMDLs may be based on point source pollution “when nonpoint
    and background sources have relatively little impact on water quality.” 
    Id. at 1314
    .
    Relators argue that the “plain language” of the statute requires the MPCA to develop
    a separate load allocation for the natural background of Little Rock Creek. Federal law
    instructs an agency to distinguish between natural and nonpoint source loads “[w]herever
    possible.” 
    40 C.F.R. § 130.2
    (g). However, Minnesota law does not compel the MPCA to
    develop a separate load allocation for natural background sources, distinct from nonpoint
    sources. A review of the statutory language is instructive. Chapter 114D defines a TMDL
    as “the sum of pollutant load allocations for all sources of the pollutant” based on four
    elements: “a wasteload allocation for point sources, a load allocation for nonpoint sources
    and natural background, an allocation for future growth of point and nonpoint sources, and
    a margin of safety.” Minn. Stat. § 114D.15, subd. 10. Relators argue that “nonpoint
    sources” and “natural background” should be interpreted as separate elements. This
    interpretation is not supported by the plain and unambiguous language of the statute. The
    portion of the statute that defines TMDL contains four clauses, each of which is separated
    by a comma from the other clauses. Id. The phrase “a load allocation for nonpoint sources
    14
    and natural background” is set off by commas from the remaining three clauses. Id. If
    “nonpoint sources” and “natural background” were intended to be read separately they
    would have been separated by a comma or other disjunctive phrase. See, e.g., State v.
    Rausch, 
    799 N.W.2d 19
    , 23 (Minn. App. 2011) (advising that statutory language that is not
    “subdivided or separated” should be read as a whole) (citing Munger v. State, 
    749 N.W.2d 335
    , 338 (Minn. 2008) (stating that under “normal rules of grammatical construction,” a
    statute’s several parts will be interpreted separately when signified by a disjunctive
    conjunction or separated by a comma)).           Here, “nonpoint sources” and “natural
    background” are not separated by a comma or otherwise set apart from one another. See
    Minn. Stat. § 114D.15, subd. 10. Thus, according to a plain and ordinary reading of the
    statute, the legislature chose not to separate “nonpoint sources” from “natural background.”
    Therefore, relators’ assertion that the statute requires the MPCA to develop an independent
    load allocation for nonpoint sources, as well as a second load allocation for natural
    background, is not well-founded. See Dupey v. State, 
    868 N.W.2d 36
    , 39 (Minn. 2015)
    (“[I]f the statutory language is unambiguous, [the court] must enforce the plain meaning of
    the statute and not explore the spirit or purpose of the law.”); Christianson v. Henke, 
    831 N.W.2d 532
    , 536 (Minn. 2013) (discussing statutory interpretation).
    Relators also argue that 
    Minn. R. 7050
    .0170 “establishes a simple procedure for
    determining the ‘natural background’” that the MPCA failed to utilize. Rule 7050.0170
    provides that “[n]atural conditions exist where there is no discernible impact from point or
    nonpoint source pollutants attributable to human activity or from a physical alteration of
    wetlands.”   
    Id.
       These “[n]atural background levels are defined by water quality
    15
    monitoring.” 
    Id.
     “Where water quality monitoring data are not available, background
    levels can be predicted based on data from a watershed with similar characteristics.” 
    Id.
    “Where background levels exceed applicable standards, the background levels may be used
    as the standards for controlling the addition of the same pollutants from point or nonpoint
    source discharges in place of the standards.” 
    Id.
     Rule 7050.0170 does not control our
    analysis because relators have not identified any facts in the record suggesting that the
    natural background levels “exceed applicable standards.” Moreover, rule 7050.0170
    provides only that the agency “may” use natural background levels, and statutory
    construction informs us that “‘[m]ay’ is permissive.” 
    Minn. Stat. § 645.44
    , subd. 15
    (2014).
    On appeal, this court defers to the MPCA’s expertise, In re N. Dakota Pipeline Co.
    LLC, 869 N.W.2d at 696, and we do not replace the agency’s findings with our own. In re
    Rocheleau, 
    686 N.W.2d at 891
    . Based upon the agency record before us, along with our
    de novo review of the governing statutory framework, we determine that the MPCA did
    not err by considering nonpoint sources and natural background sources together in the
    creation of the Little Rock Creek TMDL.
    c. The MPCA did not exceed its scope of authority.
    Relators argue that the MPCA exceeded the scope of its authority in approving the
    TMDL because only the DNR may regulate and control water usage in Minnesota. See
    Minn. Stat. § 103G.255 (2014) (authorizing the commissioner of natural resources to
    allocate and control the waters of the state). Relators have not provided authority to support
    this contention. Federal regulations require states to establish TMDLs for water quality for
    16
    impaired waters and require that “[d]eterminations of TMDLs shall take into account
    critical conditions for stream flow, loading, and water quality parameters.” 
    40 C.F.R. § 130.7
    (c)(1) (2014). A TMDL also accounts for “the normal water temperatures, flow
    rates, seasonal variations, existing sources of heat input, and the dissipative capacity of the
    identified waters” in determining the total maximum thermal load where water temperature
    is an issue. 
    Id.,
     (c)(2); see also 
    33 U.S.C. § 1313
    (c)(2)(A) (providing that a state’s water
    quality standards must be established “taking into consideration [each body of water’s] use
    and value”). For the reasons stated above, the MPCA correctly followed the procedures
    outlined by federal and state law in establishing a TMDL for Little Rock Creek and did not
    exceed its authority.
    III.   The denial of a contested-case hearing was not error.
    We review the denial of a contested-case hearing request under 
    Minn. Stat. § 14.69
    .
    In re Solid Waste Permit for the NSP Red Wing Ash Disposal Facility, 
    421 N.W.2d 398
    ,
    403 (Minn. App. 1988), review denied (Minn. May 18, 1988). A contested-case hearing
    must be held if:
    A. there is a material issue of fact in dispute concerning the
    matter pending before the board or commissioner;
    B. the board or commissioner has the jurisdiction to make a
    determination on the disputed material issue of fact; and
    C. there is a reasonable basis underlying the disputed material
    issue of fact or facts such that the holding of a contested
    case hearing would allow the introduction of information
    that would aid the board or commissioner in resolving the
    disputed facts in making a final decision on the matter.
    
    Minn. R. 7000
    .1900, subp. 1 (2009).
    17
    The party requesting a contested-case hearing bears the “burden of demonstrating
    the existence of material facts that would aid the agency before [it is] entitled to a contested
    case hearing.” Red Wing Ash Disposal Facility, 
    421 N.W.2d at 404
    . Conversely, a
    contested-case hearing is unnecessary if there are no material facts in dispute. In re
    Kandiyohi Co-op. Elec. Power Ass’n, 
    455 N.W.2d 102
    , 106 (Minn. App. 1990). The
    MPCA has wide discretion to determine whether a party has met its burden to show that a
    contested-case hearing is warranted. See, e.g., In re N. States Power Co. v. Wilmarth
    Indust. Solid Waste Incinerator Ash Storage Facility, 
    459 N.W.2d 922
    , 923 (Minn. 1990).
    Relators argue that the MPCA erred by denying their request for a contested-case
    hearing. The MPCA denied relators’ hearing requests on the ground that the petitions
    “fail[ed] to show the existence of a disputed material issue of fact” and instead disputed
    “the interpretation and application of law and guidance.” We agree. Relators’ petitions
    argued that nonpoint sources must be distinguished from natural background sources, and
    urged the MPCA to “properly determine the natural background levels of the load
    allocation” in light of this argument. The MPCA reasoned that hearings were unnecessary
    because relators’ petitions asserted questions of law or policy, as opposed to questions of
    fact.4
    4
    On appeal, relators argue that the MPCA must make further findings on the natural
    background levels, which could be more completely resolved through the introduction of
    testimony and evidence at a hearing. Relators contend that they will submit evidence in
    the form of scientific studies, reports, and expert witness testimony to aid in establishing
    load allocations. However, relators have not offered specific facts or information
    buttressing this argument. See Red Wing Ash Disposal Facility, 
    421 N.W.2d at 404
     (stating
    that party failed to raise any fact issues which could be resolved in a contested-case hearing
    because they did not provide “any indication of what specific new facts an expert might
    18
    We therefore conclude that the MPCA did not err by declining to grant a contested-
    case hearing where the petitions asserted legal, rather than factual, arguments. See Costle
    v. Pac. Legal Found., 
    445 U.S. 198
    , 204, 
    100 S. Ct. 1095
    , 1100 (1980) (“If a request for
    an adjudicatory hearing raises only legal issues, a hearing will not be granted[.]”); In re
    Kandiyohi Co-op. Elec. Power Ass’n, 
    455 N.W.2d at 106
     (“Where no genuine or material
    issue of fact is presented the court or administrative body may pass upon the issues of law
    after according the parties the right of argument.”) (quotations omitted).
    Affirmed.
    testify to”); 
    Minn. R. 7000
    .1800, subp. 2(a) (predicating a hearing on the existence of a
    material issue of fact which supports “a board or commissioner decision to hold a contested
    case hearing”).
    19