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Full Opinion
Lloyd GOODELL, Dennis Goodell, and Scott Goodell, Appellants,
v.
HUMBOLDT COUNTY, Iowa, and Doug Wood, Appellees.
HUMBOLDT COUNTY LIVESTOCK PRODUCERS, et al., Appellants,
v.
HUMBOLDT COUNTY, Iowa, et al., Appellees.
Supreme Court of Iowa.
*488 Eldon L. McAfee of Beving, Swanson & Forrest, P.C., Des Moines, for appellants Humboldt County Livestock Producers, et al.
Brian L. Wirt and Gary M. Myers of Davis, Brown, Koehn, Shors & Roberts, P.C., Des Moines, for appellants Lloyd Goodell, Dennis Goodell, and Scott Goodell.
James E. Brick of Brick, Gentry, Bowers, Swartz, Stoltze, Schuling & Levis, P.C., Des Moines, for appellees.
Paul S. Swinton of Morain, Burlingame & Pugh, P.L.C., West Des Moines, for amici curiae Agribusiness Association of Iowa, Iowa Cattlemen's Association, Iowa Corn Growers Association, Iowa Dairy Products Association, Iowa Farm Bureau Federation, Iowa Institute for Cooperatives, Iowa Pork *489 Producers Association, Iowa Poultry Association, Soybean Association, and Iowa Turkey Federation, and Christina L. Gault of Iowa Farm Bureau Federation, West Des Moines, for amicus curiae Iowa Farm Bureau Federation.
Considered en banc.
TERNUS, Justice.
The regulation of livestock confinement operations is a matter of growing public debate in this state. In the case before us, livestock producers have challenged four ordinances adopted by the Humboldt County Board of Supervisors that regulate large livestock confinement facilities and operations. The plaintiffs claim the ordinances are invalid because they address a matter of statewide concern, and because the county's authority has been preempted by the Iowa legislature. The defendants seek to sustain the validity of the ordinances as a valid exercise of the county's home rule authority. The district court upheld all but one section of one ordinance. Because we conclude the county's authority to enact these ordinances has been preempted by the legislature, we reverse the district court's ruling and remand for entry of summary judgment in favor of the plaintiffs.
I. Background Facts and Proceedings.
A. The ordinances. In October of 1996, the Humboldt County Board of Supervisors adopted four ordinances applicable to "large livestock confinement feeding facilities."[1] Each ordinance addresses a different matter of concern to the county: (1) ordinance 22 imposes a permit requirement prior to construction or operation of a regulated facility; (2) ordinance 23 establishes financial security requirements; (3) ordinance 24 implements groundwater protection policies; and (4) ordinance 25 governs toxic air emissions from regulated facilities. We will highlight the pertinent provisions of each ordinance.
1. Ordinance 22permit requirement. Ordinance 22 requires any person who desires to construct a large livestock confinement feeding facility to obtain a "notice of construction or operation" before construction or operation of the facility commences.[2] The owner or operator of the proposed facility must file a completed application with the Humboldt County auditor containing the following information: (1) a blueprint of the facility; (2) a statement of manure management, including a manure disposal plan; (3) the parties who will supervise the construction and initial operation of the facility; (4) a plan for runoff management; (5) identification of agricultural drainage tile lines and the remedial measures to be taken to protect their integrity; and (6) identification of agricultural drainage wells, natural sinkholes, artificial open drainage ditches, ponds, streams, lakes, marshlands, and quarries that may be affected by the new building.
The auditor is required to forward the application to the Humboldt County environmental protection officer. If the application is complete, the environmental protection officer conducts an independent investigation to ensure the proposed facility "complies with all applicable statutes, ordinances, and regulations." Once the environmental protection officer concludes the facility complies, the application is forwarded to the county board of supervisors; at the same time, neighboring property owners are also informed of the pending application. After a thirty-day period for public comment, the *490 board must issue a permit if the requirements of the ordinance have been satisfied.
Any person who begins construction or operation of a regulated facility without the required permit is guilty of a county infraction punishable by a civil penalty of not more than $100 for each day the person is in violation of the ordinance. In addition, the ordinance provides the county may seek relief under Iowa Code section 331.307 (1995).[3] Section 331.307 allows the court, in any action for a county infraction, (1) to order the defendant to abate or cease the violation, or (2) to authorize the county to abate or correct the violation, with the costs of such abatement or correction assessed against the defendant. See Iowa Code § 331.307(9)(c)(e).
2. Ordinance 23financial assurance. This ordinance provides that "no person shall operate any large livestock confinement feeding facility within Humboldt County without first providing to the [b]oard [f]inancial [a]ssurance as required under this [o]rdinance." The financial assurance required by ordinance 23 may be in the form of a surety bond, insurance, or self-insurance. The mechanism chosen must insure that funds necessary to meet the costs of cleanup and remediation for on-site and off-site contamination are available when needed. The ordinance provides a formula for calculating the projected cleanup and remediation costs. The penalties for violation of ordinance 23 are the same as specified in ordinance 22.[4]
3. Ordinance 24groundwater protection. This ordinance applies to large livestock confinement feeding operations that apply livestock manure on land. It provides, in part:
No person whose facility is subject to this [o]rdinance shall land apply livestock manure on any land in Humboldt County that drains into an agricultural drainage well or sinkhole in a manner that results in the contamination of groundwater.
In addition to this prohibition, ordinance 24 requires that a regulated facility obtain from the county's environmental protection officer a permit to apply livestock manure on land draining into agricultural drainage wells or sinkholes.
The ordinance also provides that the county will annually test such wells and sinkholes to ensure they have not been contaminated by livestock manure. If contamination occurs, the facility's permit for land application of livestock manure is automatically suspended. Any person who land applies livestock manure without the required permit is guilty of a county infraction with the same penalties and relief provided in ordinance 22.
4. Ordinance 25toxic air emissions. Article one of ordinance 25 prescribes the minimum distance that regulated facilities may be located from any residence, other facility, or public use area "if the regulated facility is not able to confine toxic air emissions on site." Article two prohibits regulated facilities from any off-site emission of hydrogen sulfide concentrations in excess of a specified level. If emissions exceed this level, the facility owner or operator must redesign the project, add abatement equipment, or close the facility. The penalties for violation of this ordinance mirror those of the other ordinances.
B. The lawsuit. This litigation is the consolidation of two actions for declaratory judgment that challenged the county's ordinances. One action was brought by the Humboldt County Livestock Producers and several of its members against the county, the board of supervisors, the individual board *491 members, and the county zoning administrator, who also serves as the county's environmental protection officer. A second action against the county and the zoning administrator was filed by Lloyd Goodell, Dennis Goodell and Scott Goodell, residents of Humboldt County who planned to construct hog confinement facilities falling within the ordinances' definition of "large livestock confinement feeding operation."[5] Both actions sought a declaratory judgment from the district court that the challenged ordinances were invalid and violated the plaintiffs' constitutional rights.
The ruling from which this appeal was taken resulted from the parties' cross-motions for summary judgment on the question of the county's authority to adopt the ordinances. (The constitutional claims were reserved for later consideration by the court.) The district court concluded that article one of ordinance 25, imposing minimum distances between regulated facilities and other facilities, residences and public use areas, constituted zoning of land and buildings used for agricultural purposes. The court ruled this part of ordinance 25 violated Iowa Code section 335.2, which prohibits counties from zoning agricultural land and structures. As a consequence, the court declared article one of ordinance 25 invalid, and granted summary judgment to the plaintiffs as to this provision.
The district court ruled ordinances 22, 23, and 24 were valid exercises of the county's home rule authority. Although the court also upheld article two of ordinance 25, the court concluded it was unenforceable until the county had complied with Iowa Code section 455B.145.[6]See Iowa Code § 455B.145 (requiring local governmental entities to obtain a certificate of acceptance from the Department of Natural Resources for any local air pollution control program). Accordingly, the court granted summary judgment to the county with respect to these ordinances, with the limitation noted as to ordinance 25.
In response to all parties' motions for an enlargement of the court's findings pursuant to Iowa Rule of Civil Procedure 179(b), the court issued an order holding that its ruling was dispositive of all issues in the Livestock Producers' case. As for the Goodells' suit, the court held that its summary judgment ruling pertained only to the validity of the ordinances and that all other issues not addressed were reserved for future proceedings.
The plaintiffs appealed the district court's summary judgment ruling. Because that ruling was not final as to the Goodell plaintiffs, we granted permission for an interlocutory appeal. The county did not appeal the trial court's adverse rulings with respect to ordinance 25.
II. Scope of Review.
We will uphold a summary judgment "when the moving party shows no genuine issue of material fact exists and it is entitled to judgment as a matter of law." C-Thru Container Corp. v. Midland Mfg. Co., 533 N.W.2d 542, 544 (Iowa 1995) (citing Iowa R. Civ. P. 237(c)). Thus, on appeal, "we must decide (1) whether a genuine issue of material fact exists, and (2) if the law was correctly applied." Hegg v. Hawkeye Tri-County REC, 512 N.W.2d 558, 559 (Iowa 1994).
In this case, the parties agree there is no dispute with respect to material facts; the disagreement centers on the interpretation of state laws and the effect of those laws on the county's authority to regulate livestock confinement operations. Our role is simply to decide whether we agree with the district court's application of the law to the undisputed facts before us. Therefore, our review is at law. See City of Clinton v. Sheridan, 530 N.W.2d 690, 692 (Iowa 1995).
III. Home Rule Authority and Preemption.
In deciding the validity of the county's ordinances, we must consider two concepts: *492 (1) the county's home rule authority, and (2) the state's power to abrogate or preempt local action. These concepts and their interrelationship are set forth in Iowa's constitutional grant of county home rule authority. See Iowa Const. art. III, § 39A (added by amend. 37 in 1978). Under this constitutional amendment, counties have the power "to determine their local affairs and government," but only to the extent those determinations are "not inconsistent with the laws of the general assembly." Id.[7] The goal of this amendment was to grant counties "power to rule their local affairs and government subject to the superior authority of the general assembly." Sheridan, 530 N.W.2d at 693 (citing Bechtel v. City of Des Moines, 225 N.W.2d 326, 332 (Iowa 1975)).
A. County home rule authority. The constitutional parameters of county home rule are echoed in chapter 331 of the Iowa Code. Section 331.301 sets forth the general scope of a county's power and its limitations:
A county may, except as expressly limited by the Constitution, and if not inconsistent with the laws of the general assembly, exercise any power and perform any function it deems appropriate to protect and preserve the rights, privileges, and property of the county or of its residents, and to preserve and improve the peace, safety, health, welfare, comfort, and convenience of its residents.
Iowa Code § 331.301(1). Pursuant to this provision, counties now have the authority to act "unless a particular power has been denied them by statute." City of Des Moines v. Master Builders of Iowa, 498 N.W.2d 702, 703-04 (Iowa 1993).
The concept of home rule envisions the possibility that state and local governments will regulate in the same area:
A county shall not set standards and requirements which are lower or less stringent than those imposed by state law, but may set standards and requirements which are higher or more stringent than those imposed by state law, unless a state law provides otherwise.
Iowa Code § 331.301(6); see Sam F. Scheidler, Implementation of Constitutional Home Rule in Iowa, 22 Drake L.Rev. 294, 313 (1973) (interpreting comparable provision in chapter 364, dealing with city home rule authority, as the legislature's recognition "that the city and state will often be legislating in the same area") [hereinafter Home Rule in Iowa]. Thus, subject to this restriction and principles of preemption, a county may exercise its home rule powers on matters that are also the subject of state law. See Decatur County v. PERB, 564 N.W.2d 394, 398 (Iowa 1997); Sioux City Police Officers' Ass'n v. City of Sioux City, 495 N.W.2d 687, 694 (Iowa 1993).
B. Preemption. Preemption may be express or implied. Both forms of preemption find their source in the constitution's prohibition of the exercise of a home rule power "inconsistent with the laws of the general assembly." Iowa Const. art. III, § 39A; see Home Rule in Iowa, 22 Drake L.Rev. at 305 ("That home rule power must not be inconsistent with the laws of the General Assembly raises a pre-emption problem."). Chapter 331 further defines this limitation: "An exercise of a county power is not inconsistent with a state law unless it is irreconcilable with the state law." Iowa Code § 331.301(4).
1. Express preemption. Express preemption occurs when the general assembly has specifically prohibited local action in an area. E.g., Chelsea Theater Corp. v. City of Burlington, 258 N.W.2d 372, 373 (Iowa 1977) (holding state has expressly proscribed local regulation of obscene materials). Obviously, any local law that regulates in an area the legislature has specifically stated cannot be the subject of local action is irreconcilable with state law.
*493 2. Implied preemption. Implied preemption occurs in two ways. When an ordinance "`prohibits an act permitted by a statute, or permits an act prohibited by a statute,'" the ordinance is considered inconsistent with state law and preempted. City of Des Moines v. Gruen, 457 N.W.2d 340, 342 (Iowa 1990) (quoting City of Council Bluffs v. Cain, 342 N.W.2d 810, 812 (Iowa 1983)).
Implied preemption may also occur when the legislature has "cover[ed] a subject by statutes in such a manner as to demonstrate a legislative intention that the field is preempted by state law." Cain, 342 N.W.2d at 812; see also 5 Beth A. Buday & Victoria A. Braucher, McQuillin Municipal Corporations § 15.20, at 109 (3d ed. 1996 rev. vol.) ("Where the state has preempted the field, local law regulating the same subject is inconsistent with the state's transcendent interest, whether or not the terms of the local law actually conflict with the statewide legislation.") [hereinafter 5 McQuillin Municipal Corporations]. "[T]he mere fact that the legislature has enacted a law addressing a subject does not mean that the subject matter is completely preempted." 5 McQuillin Municipal Corporations § 15.20, at 107. As we discuss in greater detail below, Iowa law requires some legislative expression of an intent to preempt home rule authority, or some legislative statement of the state's transcendent interest in regulating the area in a uniform manner. This approach is consistent with the legislature's statement in chapter 331 that "[a] county may exercise its general powers subject only to limitations expressly imposed by a state law." Iowa Code § 331.301(3) (emphasis added); accord Gruen, 457 N.W.2d at 343 ("Limitations on a municipality's power over local affairs are not implied; they must be imposed by the legislature.").
We turn now to the specific issues before us in this appeal.
IV. Issues on Appeal.
The plaintiffs claim the trial court incorrectly ruled that the ordinances adopted by Humboldt County were within its home rule authority. They claim the ordinances are invalid for several reasons: (1) the ordinances regulate a matter of statewide concern, which is beyond the county's authority over "local affairs"; (2) the ordinances violate the prohibition of local zoning of agricultural land and structures found in section 335.2; (3) the comprehensive nature of state regulation of animal feeding operations indicates the legislature intended to preempt local government from regulating in this area; and (4) the ordinances directly conflict with state statutes and rules.[8]
As we summarize the issues before us in this case, we think it important also to identify the issues that are not before us. This distinctionbetween issues that we must decide and issues we cannot decideis rooted in the different roles played by the legislative and judicial branches in our system of government. The chief characteristic of the legislative function is the determination of broad policies or principles for the conduct of society's affairs. See 1 Norman J. Singer, Sutherland Statutory Construction § 1.03, at 5 (5th ed. 1994). These legislative statements of principles and policies are known as statutes. See id. The judicial branch, in reviewing legislative action, has the authority to determine whether the legislature's enactments are constitutional and valid. See id. § 2.01, at 15. A court cannot refuse to enforce a statute on the ground that it is unwise. See id.; see also Hines v. Illinois Cent. Gulf R.R., 330 N.W.2d 284, 289 (Iowa 1983) ("In construing statutes it is our duty to determine legislative intent; the wisdom of the legislation is not our concern.").
With this background in the distinctive and different roles of the legislature and the courts with respect to statutory law, we now turn to the case before us. In this matter of public interest, our court is limited to determining *494 whether Humboldt County had the authority to enact the challenged ordinances. The wisdom of those ordinances is not before us. Nor is it our role to decide whether local government should be allowed to regulate livestock confinement operations. The question before us is simply whether, under the constitution and state law, the county can regulate in this area.
V. Home Rule AuthorityDo the Ordinances Regulate a "Local Affair"?
The plaintiffs contend that the regulation of livestock confinement feeding operations is a matter of statewide concern. They conclude, therefore, that these operations are not a "local affair" as contemplated by the home rule amendment. See Iowa Const. art. III, § 39A (giving counties home rule authority and power "to determine their local affairs and government"). We reject this assertion. Ensuring that livestock operations within a county are conducted in such a manner as to avoid contamination of the environment and interference with others' enjoyment and use of their property is a matter of local concern and, therefore, is a "local affair" within the meaning of the home rule amendment.
A local matter may, however, also have statewide importance. See 2 Dennis Jensen & Gail A. O'Gradney, McQuillin Municipal Corporations § 4.85, at 203 (3d ed. 1996 rev. vol.). Consequently, characterizing the subject of the challenged ordinances as a local affair does not prevent the legislature from imposing uniform regulations throughout the state, should it choose to do so, nor does it prevent the state from regulating this area in such a manner as to preempt local control. See id. We turn now to an examination of whether the state has, indeed, preempted local authorities from regulating livestock feeding operations.
VI. Express PreemptionDo the Ordinances Constitute Invalid County Zoning of Agricultural Land and Structures?
A. County zoning authority. Iowa Code chapter 335 establishes general zoning authority for counties, the scope of such authority, and the procedures for exercising that authority. See generally Iowa Code ch. 335. One limitation on the county's zoning power is the express preemption of county zoning of agricultural land and structures:
[N]o ordinance adopted under this chapter applies to land, farm houses, farm barns, farm outbuildings or other buildings or structures which are primarily adapted, by reason of nature and area, for use for agricultural purposes, while so used.
Id. § 335.2. Although the act containing this provision did not state the purpose of the exemption, a predecessor bill having the same exemption asserted that the agricultural exception to county zoning was "intended as a protection for the farmer and his investment in his land." H.F. 426, 1947 H.J. 587 (comments and explanation); see Note, County Zoning in Iowa, 45 Iowa L.Rev. 743, 754 (1960); see also Neil D. Hamilton, Freedom to Farm! Understanding the Agricultural Exemption to County Zoning in Iowa, 31 Drake L.Rev. 565, 574 (1981-82) ("the exemption of section 358A.2 [now section 335.2] was a significant statement of the `freedom to farm'").
The parties agree the ordinances enacted by Humboldt County apply to land and structures used for agricultural purposes. See Kuehl v. Cass County, 555 N.W.2d 686, 689 (Iowa 1996) (holding hog confinement facility was exempt from county zoning regulations under section 335.2). The fighting issue is whether any of the ordinances constitute an "ordinance adopted under ... chapter [335]"; in other words, are the ordinances zoning regulations?
B. Procedure of adoption. The county asserts the ordinances were enacted pursuant to the home rule authority granted in chapter 331 and not pursuant to the zoning power granted in chapter 335. The county points out it did not consult its comprehensive plan prior to enactment of the challenged ordinances nor did it follow the other procedures outlined in chapter 335. See Iowa Code §§ 335.6-.17. But chapter 331 mandates that any zoning power "shall be exercised in accordance with chapter 335." Id. § 331.304(6). This provision makes it *495 clear that a county does not have a choice to enact an ordinance under chapter 331 or chapter 335. If the regulation constitutes zoning, the county must follow the procedures and be subject to the limitations of chapter 335. See Thompson v. Hancock County, 539 N.W.2d 181, 183 (Iowa 1995) (holding agricultural exemption is incorporated into zoning regulations enacted under home rule authority of chapter 331). Consequently, a county may not avoid the agricultural exemption simply by labeling a zoning ordinance an exercise of home rule authority and ignoring the procedural requirements of chapter 335. See Land Acquisition Servs., Inc. v. Clarion County Bd. of Comm'rs, 146 Pa.Cmwlth. 293, 605 A.2d 465, 469 (1992) ("[T]he stated intent of a municipality is not controlling with respect to the question of whether the substance of an ordinance renders it a zoning ordinance.").
C. Purpose of ordinances. That brings us to another argument made by the county to support its position that the challenged ordinances are not zoning regulations. The county points out the purpose of the ordinances is not to regulate land usage, but "to create safeguards to protect the integrity of environmental resources in Humboldt County from potential hazards resulting from permitted acts," and to protect "the health, safety and welfare of Humboldt County residents." Accordingly, it contends, the ordinances are an exercise of the county's police power. See Gravert v. Nebergall, 539 N.W.2d 184, 186 (Iowa 1995) (stating the police power is the authority "to pass laws that promote the public health, safety, and welfare").
But the purpose of the regulations does little to assist us in classifying them as the exercise of general police power or the exercise of zoning power. Indeed, any zoning regulation is, by definition, an exercise of the county's police power. See Montgomery v. Bremer County Bd. of Supervisors, 299 N.W.2d 687, 692 (Iowa 1980) ("Zoning decisions are an exercise of the police power to promote the health, safety, order and morals of society."); see also Iowa Code § 335.5 (stating one objective of zoning is "to protect health and the general welfare"). Consequently, the county's goal of protecting its natural resources and citizens from the unwanted effects of confinement operations is as consistent with the exercise of zoning power as it is with an exercise of the county's home rule authority.
D. What constitutes zoning under chapter 335? If the label placed on these ordinances and the purpose for which they were enacted do not assist us in determining whether they are prohibited zoning regulations, what is the test? We think we must necessarily start with the wording of the statute itself to interpret the scope of chapter 335. See Collins v. King, 545 N.W.2d 310, 312 (Iowa 1996) ("In interpreting a statute we necessarily begin with the statute's language.").
The zoning power of the county regulated by chapter 335 is described in the statute itself:
Subject to section 335.2, the board of supervisors may by ordinance regulate and restrict the height, number of structures, and size of buildings and other structures, the percentage of lot that may be occupied, the size of yards, courts, and other open spaces, the density of population, and the location and use of buildings, structures, and land for trade, industry, residence, or other purposes, and may regulate, restrict, and prohibit the use for residential purposes of tents, trailers, and portable or potentially portable structures.
Iowa Code § 335.3 (emphasis added). The statute further provides that the board "may divide the county ... into districts ... and within such districts it may regulate and restrict the erection, construction, reconstruction, alteration, repair, or use of buildings, structures or land." Id. § 335.4 (emphasis added). The statute requires that any regulation adopted pursuant to chapter 335 advance certain enumerated objectives, including "to protect health and the general welfare." Id. § 335.5.
Based on this statute, the plaintiffs argue any county ordinance that regulates the "use" of buildings or land to protect the public's health or general welfare is zoning. The county responds that the challenged ordinances do not constitute zoning because *496 they do not regulate land usage by district. It points out the challenged ordinances regulate an activity and apply uniformly across the county, irrespective of district classifications.[9] We think the county's understanding of the distinction between a zoning power and a general police power with respect to the regulation of an activity on land is correct.[10]
Historically, zoning regulations took the form of separating geographic areas according to zoning districts and specifying the uses permitted in each district. See 1 Patrick J. Rohan, Zoning and Land Use Controls § 1.02[1], at 1-6 (1991) [hereinafter Zoning and Land Use Controls]. Zoning has expanded, however, since its beginnings in the early twentieth century and today's land use regulations are far more flexible and complex. See 6 Zoning and Land Use Controls § 40.01[1][b], at 40-5; see also Plaza Recreational Ctr. v. Sioux City, 253 Iowa 246, 249, 111 N.W.2d 758, 761 (1961) (upholding a city zoning ordinance that restricted the types of bowling alleys allowed in a D-1 district to those "which do not permit the consumption of beer or intoxicating liquor on the premises"). Zoning regulations may now take the form of "performance controls" to limit the uses occurring in a particular district. See 6 Zoning and Land Use Controls § 40A.03[1][b], at 40A-21 to 40A-23 (noting the use of standards for "traffic, noise, dust, odors, or other like problems" to regulate or limit uses).
Despite expansion in the type of regulation imposed by zoning ordinances, the fundamental attribute of use regulation by district remains. See, e.g., 83 Am.Jur.2d Zoning § 2, at 36 (1992) ("The very essence of zoning is the territorial division of land into use districts according to the character of the land and buildings, the suitability of land and buildings for particular uses, and uniformity of use.") (emphasis added); Black's Law Dictionary 1618 (6th ed.1990) (defining "zoning," in part, as "[d]ivision of land into zones, and within those zones, regulation of both the nature of land usage and the physical dimension of uses including height[,] setbacks and minimum area") (emphasis added); 8 J. Jeffrey Reinholtz & Timothy P. Bjur, McQuillin Municipal Corporations § 25.07, at 27 (3d ed.1991 rev. vol.) ("`Zoning' has been defined as the legislative division of a community into areas in which only certain designated uses of land or structures are permitted. The term ... infers governmental regulation of the uses of land and buildings according to districts or defined areas.") (emphasis added); id. § 25.53, at 172 ("A zoning ordinance is one the nature and purpose of which is to regulate uses of lands and buildings according to districts, areas, or locations.") (emphasis added); 1 Zoning and Land Use Controls § 1.02[1], at 1-6 ("Zoning ordinances are adopted to divide the land into different districts, and to permit only certain uses within each zoning district.") (emphasis added); 6 Zoning and Land Use Controls § 40.01[1][a], at 40-03 ("The central thesis of zoning is that there is a proper place for every use.") (emphasis added).
It is this fundamental attribute that is missing in the challenged ordinances; they regulate an activity irrespective of the location of that activity within the county. Thus, although the ordinances may advance the health and general welfare of the community, they do not do so by regulating the usage of land by district. See City of Batavia v. Allen, 218 Ill.App.3d 545, 547, 161 Ill.Dec. 239, 241, 578 N.E.2d 597, 599 (1991) (holding ordinance requiring taverns to close doors and windows during business hours was a licensing restriction and not a zoning provision because "it regulates establishments based on the type of business they conduct, not based on their location"); Square Lake Hills Condominium Ass'n v. Bloomfield Township, 437 Mich. 310, 471 N.W.2d 321, 326 (1991) (holding ordinance regulating boat *497 docking and launching was not a zoning ordinance because it regulated an activity, and not the use of land and buildings according to districts); Town of Islip v. Zalak, 165 A.D.2d 83, 566 N.Y.S.2d 306, 311 (1991) (holding ordinance regulating recycling stations was not a zoning ordinance because it regulated an activity wherever it was carried out).
We note a contrary conclusion would lead to an absurd result. See Hagen v. Texaco Refining & Mktg., Inc., 526 N.W.2d 531, 543 (Iowa 1995) (stating court seeks a reasonable construction of a statute that will "avoid absurd results"). The plaintiffs argue the county's ordinances substantially restrict the use of land and hence are zoning regulations. But that could be said of any regulation of human activity because human activity customarily occurs on land or in a structure on land. See Town of Islip, 566 N.Y.S.2d at 311 (noting a law is not a zoning ordinance "merely because it touches the use of land"). Because any regulation of human activity could be characterized as a regulation of the use of one's land, the classification of an ordinance as zoning on the basis that the regulation affects the use of land would make every city or county ordinance a zoning ordinance, subject to the restrictions and procedures of chapter 335.
We are confident the legislature did not intend chapter 335 to have such a broad application. For example, section 335.5 requires that any zoning regulation "be made in accordance with a comprehensive plan"[11] and further that "[s]uch regulations shall be made with reasonable consideration, among other things, as to the character of the area of the district and the peculiar suitability of such area for particular uses." (Emphasis added.) Additionally, section 335.4 requires that any regulation or restriction must "be uniform for each class or kind of buildings throughout each district, but the regulations in one district may differ from those in other districts." (Emphasis added.) The statute clearly contemplates that land use regulation under chapter 335 will have the fundamental characteristic of zoningregulation by district.
We applied this distinction in Hawkeye Outdoor Advertising, Inc. v. Board of Adjustment, 356 N.W.2d 544 (Iowa 1984), a case interpreting chapter 414, the city zoning statute. In that case, the plaintiff wanted to erect a twenty-six-foot-high billboard, but the city's sign ordinance limited billboards to twenty feet. Hawkeye Outdoor Adver., 356 N.W.2d at 546. The plaintiff sought a variance from the board of adjustment, but the board declined to act on the basis it had no jurisdiction. Id. The question of jurisdiction turned on whether the sign ordinance was a zoning ordinance, subject to variance by the board, or an exercise of the city's general home rule authority. Id. We held the sign ordinance was not a zoning ordinance, in part, because it did not "deal with zoning, or restrictions of that sort." Id. We characterized a "zoning measure" as one "which regulates the use of property in designated areas." Id. (emphasis added).
Because the ordinances adopted by Humboldt County do not regulate land use by district, they are not an exercise of the county's zoning power under chapter 335. Therefore, the ordinances are not subject to the agricultural exemption of section 335.2. We agree with the district court's conclusion that the challenged ordinances are not invalid under chapter 335.
VII. Implied PreemptionHas the State Completely Occupied the Field of Livestock Feeding Operations?
The plaintiffs assert the legislature has so fully and extensively regulated livestock feeding operations that any local regulation would be inconsistent with the state regulatory framework. They also argue regulation of animal feeding operations is a matter of statewide concern and should be uniform across the state. Based on the nature of the subject to be regulated, the plaintiffs claim local laws are preempted. In evaluating these arguments, we begin with a review of *498 the guiding legal principles in Iowa on implied preemption.
A. Applicable analytical framework. Since the adoption of home rule in Iowa, we have continued to recognize that preemption may occur when the legislature has "cover[ed] a subject by statutes in such a manner as to demonstrate a legislative intention that the field is preempted by state law." Cain, 342 N.W.2d at 812; accord Gruen, 457 N.W.2d at 342 ("A municipal ordinance also is preempted by state law when the ordinance invades an area of law reserved by the legislature to itself.") (citing Cain, 342 N.W.2d at 812). Although this principle is simple to state, its application is less obvious.
Both parties counsel a broad approach toward ascertaining implied preemption. They suggest that the court consider not only the statutory and regulatory treatment of livestock feeding operations, but also the nature of the issues to be addressed by state and local laws in this area. In essence, they ask the court to make a policy decision as to whether this area should be regulated on a statewide basis, rather than to simply decide whether this area has been regulated in such a way as to evidence the legislature's intent to reserve the area for uniform regulation. The plaintiffs cite several cases from other jurisdictions in which the courts have, in varying degrees, considered the nature of the subject matter being regulated and the need for statewide uniformity as one factor in determining whether there has been an implied preemption of the field. E.g., Envirosafe Servs. of Idaho, Inc. v. County of Owyhee, 112 Idaho 687, 735 P.2d 998, 1000 (1987); Gora v. City of Ferndale, 210 Mich.App. 622, 533 N.W.2d 840, 842 (1995), vacated, 451 Mich. 875, 549 N.W.2d 567 (1996); Mangold Midwest Co. v. Village of Richfield, 274 Minn. 347, 143 N.W.2d 813, 819-20 (1966); Halpern v. Sullivan County,