Justice HOBBS delivered the Opinion of the Court.

We granted certiorari in Colorado Mining Association v. Board of County Commissioners of Summit County, 170 P.3d 749 (Colo.App. 2007), to determine whether Colorado's Mined Land Reclamation Act ("the MLRA") preempts an ordinance Summit County adopted, invoking its statutorily-delegated land use authority. Summit County banned the use of toxic or acidic chemicals, such as cyanide, for mineral processing in vat or heap leach operations for all zoning districts in the county. The effect of this ordinance is to prohibit a certain type of mining technique customarily used in the mineral industry to extract precious metals, such as gold.

In 1993, the General Assembly examined the use of cyanide in mining operations due to an environmentally devastating incident that occurred at the Summitville Mine. The Assembly ultimately decided to allow the Mined Land Reclamation Board ("the Board") to authorize the use of such mining techniques, but only under the terms of an Environmental Protection Plan designed for each operation sufficient to protect human health, property, and the environment. Summit County's ordinance would entirely displace the Board's authority to authorize the use of such mining techniques.

The General Assembly has assigned to the Board the authority to authorize and comprehensively regulate the use of toxic or acidic chemicals, such as cyanide, in mining operations, a field identified by the legislature, see §§ 34-32-103(3.5), (4.9), -112.5, -116.5, C.R.S. (2008), that Summit County's ban ordinance would occupy, negating the Board's statutory role. We conclude that Summit County's existing ordinance is not a proper exercise of its land use authority because it excludes what the General Assembly has authorized. Due to the sufficiently dominant state interest in the use of chemicals for mineral processing, we hold that the MLRA impliedly preempts Summit County's ban on the use of toxic or acidic chemicals, such as cyanide, in all Summit County zoning districts. Accordingly, we reverse the judgment of the court of appeals, which upheld Summit County's ordinance, and uphold the judgment of the District Court for Summit County, which declared the ordinance to be unenforceable.

I.

In 2004, Summit County enacted ordinance section 3812.04 ("the ordinance") as part of its land use and development codes to provide that: "Any mining or milling operation that utilizes cyanide or other toxic/acidic ore-processing reagents in heap or vat leach applications shall not be allowed in any zoning district." Summit County, Colo., Development Code Ch. 3, § 3812.04 (2004).

Heap leaching is a technology that employs chemical solutions percolated through heaps of ore or tailings to dissolve and extract minerals; vat leaching is a similar process performed in an impermeable vat or tank. In adopting its ordinance, Summit County determined that the use of chemicals for mineral processing, especially the use of cyanide, poses unacceptable environmental and public health risks. At least four other Colorado counties have also banned the use of cyanide in mining operations.

The Colorado Mining Association challenged the ordinance in Summit County district court pursuant to C.R.C.P. 57, and obtained a judgment against its validity. The district court ruled that the ordinance is a reclamation standard that the MLRA expressly preempts.

Summit County and two intervenors, the Alliance for Responsible Mining and the Blue River Group of the Sierra Club, appealed the district court's decision, contending that the Summit County ordinance is a legitimate exercise of the county's land use authority. The court of appeals upheld the ordinance on the basis that the MLRA does not expressly or impliedly preempt the ordinance.

The Board contends that amendments adopted by the General Assembly in 1993, in the wake of the Summitville disaster, expressly or impliedly preempt the ordinance. Those amendments specifically regulate chemicals, such as cyanide, utilized for the extraction of minerals. See §§ 34-32-103(3.5), (4.9), -112.5, -116.5. Examining these amendments and taking into account the Board's reasonable interpretation of its own enabling statute, we agree with the Board that the MLRA impliedly preempts the county's ordinance, and we reverse the judgment of the court of appeals.

II.

The General Assembly assigned to the Board the authority to authorize and comprehensively regulate the use of toxic or acidic chemicals, such as cyanide, for mineral processing in mining operations, a field identified by the legislature, see §§ 34-32-103(3.5), (4.9), -112.5, -116.5, that Summit County's ban ordinance would occupy, negating the Board's statutory role. We conclude that Summit County's existing ordinance is not a proper exercise of its land use authority because it excludes what the General Assembly has authorized. Due to the sufficiently dominant state interest in the use of chemicals for mineral processing, we hold that the MLRA impliedly preempts Summit County's ban on the use of toxic or acidic chemicals, such as cyanide, in all Summit County zoning districts.

A. Standard of Review

All party and amicus curiae briefs in this case assert the applicability of preemption analysis, with contrary suggested outcomes in favor of or opposed to Summit County's ordinance. Accordingly, we turn to our preemption case law for the applicable standard of review.

"The purpose of the preemption doctrine is to establish a priority between potentially conflicting laws enacted by various levels of government." County Comm'rs v. Bowen/Edwards Assocs., 830 P.2d 1045, 1055 (Colo. 1992). Express and implied preemption are "primarily matters of statutory interpretation." Town of Carbondale v. GSS Props., LLC, 169 P.3d 675, 682 (Colo. 2007); cf. Middleton v. Hartman, 45 P.3d 721, 731 (Colo. 2002).

Our preemption methodology for resolving state and local legislative conflicts borrows from our cases involving federal preemption analysis. As we have explained, there are various ways in which federal law may preempt state law:

when Congress expresses clear intent to preempt state law; when there is outright or actual conflict between federal and state law; when compliance with both federal and state law is physically impossible; when there is an implicit barrier within federal law to state regulation in a particular area; when federal legislation is so comprehensive as to occupy the entire field of regulation; or when state law stands as an obstacle to the accomplishment and execution of the full objectives of Congress.

State Dep't of Health v. The Mill, 887 P.2d 993, 1004 (Colo. 1994); see also Brubaker v. Bd. of County Comm'rs, 652 P.2d 1050, 1055-56 (Colo. 1982). In Banner Advertising, Inc. v. People of City of Boulder, 868 P.2d 1077, 1081-83 (Colo. 1994), we relied in part on the implied preemption doctrine to invalidate a local government's ban on commercial banner towing by aircraft, because a Federal Aviation Administration ("FAA") regulation allowed pilots who had obtained an FAA certificate to tow banners.

We have applied preemption analysis in cases involving alleged conflicts between state statutes and local government land use authority. Because home rule land use authority has a basis in the Colorado Constitution, we utilize a four-part test when examining the validity of a local ordinance or regulation enacted by a home rule city or county, in the face of an alleged state conflict: "whether there is a need for state-wide uniformity of regulation; whether the municipal regulation has an extraterritorial impact; whether the subject matter is one traditionally governed by state or local government; and whether the Colorado Constitution specifically commits the particular matter to state or local regulation." Voss v. Lundvall Bros., Inc., 830 P.2d 1061, 1067 (Colo. 1992); see also City of Northglenn v. Ibarra, 62 P.3d 151, 155-56 (Colo. 2003).

In contrast, statutory counties only enjoy "those powers that are expressly granted to them by the Colorado Constitution or by the General Assembly," which include "implied powers reasonably necessary to the proper exercise of those powers that are expressly delegated." County Comm'rs v. Bainbridge, 929 P.2d 691, 699 (Colo. 1996). Accordingly, in cases involving statutory counties, we have applied the ordinary rules of statutory construction to determine whether a state statute and a local ordinance can be construed harmoniously or whether the state statute preempts the local ordinance. Id. at 698-99. If a conflict exists and the state statute contains a specific provision addressing the matter, the state statute controls over the statutory county's general land use authority. Id. at 705.

Our Bowen/Edwards decision, for example, involved a state act, the Oil and Gas Conservation Act, and a statutory county, La Plata County. 830 P.2d at 1048. The issue there was whether the state statute completely preempted the county's authority to enact land use regulations applicable to oil and gas operations in the county. Id. In reviewing the three basic ways in which a state statute can preempt a county ordinance or regulation, express preemption, implied preemption, and operational preemption, Id., at 1056-57, we found nothing in the text of the Oil and Gas Conservation Act to "support the total preemption of a county's authority to enact land-use regulations applicable to oil and gas development and operational activities within the county." Id. at 1059.

In finding implied preemption inapplicable in Bowen/Edwards, we held that the "state's interest in oil and gas activities is not so patently dominant over a county's interest in land-use control, nor are the respective interests of both the state and the county so irreconcilably in conflict, as to eliminate by necessary implication any prospect for a harmonious application of both regulatory schemes." Id. at 1058. We reasoned that a state statute and a local ordinance may both remain effective and enforceable, so as long as they do not contain express or implied conditions that irreconcilably conflict with each other. 830 P.2d at 1055-56.

We announced our decision in Voss, 830 P.2d 1061, on the same day we announced Bowen/Edwards. Voss is the flip side of Bowen/Edwards. It involved a home rule local government's ban on oil and gas drilling within its boundaries. Id. at 1062. We found the ban to be unenforceable because "the state's interest in efficient development and production of oil and gas in a manner preventative of waste and protective of the correlative rights of common-source owners and producers to a fair share of production profits preempts a home-rule city from totally excluding all drilling operations within the city limits." Id. at 1069. We held that the state interest manifested in the state act was "sufficiently dominant" to override the local ordinance. Id. at 1068.

Sufficient dominancy is one of the several grounds for implied state preemption of a local ordinance. In Ibarra, we utilized implied preemption to void a local home rule ordinance upon finding that "the state's interest in fulfilling its statutory mandates to protect adjudicated delinquent children in need of state supervision and appropriate treatment is sufficiently dominant to override a home-rule city's interest in regulating the number of registered juvenile sex offenders who may live in one foster care family." 62 P.3d at 163 (emphasis added). Relying on its land use authority, Northglenn had banned unrelated, registered sex offenders from living together in a single family home in residential zones. Id. at 153.

As shown by Voss and Ibarra, local ban ordinances that conflict with state statutes in an overlapping field of regulation are subject to preemption. Two Colorado statutes specifically address how we should resolve conflicts between local land use ordinances and state statutes. First, section 30-15-411, C.R.S. (2008), provides that any statutory county ordinance that conflicts with a state statute is void. See also City and County of Denver v. Howard, 622 P.2d 568, 570 (Colo. 1981). Second, the Local Government Land Use Control Enabling Act states that, with limited exceptions, "where other procedural or substantive requirements for the planning for or regulation of the use of land are provided by law, such requirements shall control." § 29-20-107, C.R.S. (2008).

The conflict between a statutory county ordinance and a state statute need not be direct to be impermissible; local governments generally "may not forbid that which the state has explicitly authorized." Johnson v. Jefferson County Bd. of Health, 662 P.2d 463, 471 (Colo. 1983) (where state statute provides that county health official shall serve at pleasure of county health board, the board need not follow the county's procedural rules before firing an official, because the state explicitly granted the board authority to immediately discharge officials); see also Lakewood Pawnbrokers, Inc. v. City of Lakewood, 183 Colo. 370, 374, 517 P.2d 834, 836 (1974) (local ordinance requiring pawnbrokers to provide two bonds to the city impermissibly conflicted with provision in state statutory scheme governing pawnbrokers, which requires two sureties on only one bond, because ordinance creates an additional burden not required by state law).

Mere overlap in subject matter is not sufficient to void a local ordinance. However, a local regulation and a state regulatory statute impermissibly conflict if they "contain either express or implied conditions which are inconsistent and irreconcilable with each other." Ray v. City and County of Denver, 109 Colo. 74, 77, 121 P.2d 886, 888 (1942) (internal citation omitted). In particular, local land use ordinances banning an activity that a statute authorizes an agency to permit are subject to heightened scrutiny in preemption analysis.

For example, in South Dakota Mining Association, Inc. v. Lawrence County, 155 F.3d 1005, 1007 (8th Cir. 1998), the Eighth Circuit considered a county ordinance prohibiting the issuance of permits for surface mining of gold and silver within a 40,000-acre area in the Black Hills. The purposes of the Federal Mining Act, like the MLRA, include development of an economically stable and sound mining industry and the orderly development of mineral resources. Id. at 1010. The Eighth Circuit held the local ordinance was prohibitory, rather than regulatory, and that it frustrated the accomplishment of the goals of the Federal Mining Act. Id. at 1011. The court stated: "A local government cannot prohibit a lawful use of the sovereign's land that the superior sovereign itself permits and encourages." Id.

The Tenth Circuit considered whether the federal Resource Conservation and Recovery Act ("RCRA") preempted a county ordinance in Blue Circle Cement, Inc. v. Board of County Commissioners of County of Rogers, 27 F.3d 1499 (10th Cir. 1994). There, a county required a conditional use permit for the burning of hazardous waste fuels. Id. at 1501-02. The court stated that a local ordinance may not imperil the goals of RCRA, such as the goal to facilitate the recovery of "valuable materials and energy from solid waste." Id. at 1506 (citing 42 U.S.C. § 6902(a)(ll)). The court further stated that RCRA normally preempts local ordinances that ban an activity RCRA allows, while narrower local ordinances typically will be upheld if the record demonstrates the ordinance is a "reasonable response to a legitimate local concern for safety or welfare." Id. at 1508. The Tenth Circuit cited a wide array of cases, including Rollins Environmental Services of Louisiana v. Iberville Parish Police Jury, 371 So.2d 1127, 1132 (La. 1979), which held that RCRA preempted a parish's flat ban on hazardous waste disposal within parish boundaries. Id. at 1506-07.

B. Application to this Case

The court of appeals upheld Summit County's ordinance, reasoning that its ban on cyanide and other toxic/acidic reagents for processing minerals in heap or vat leach mining operations is not a reclamation standard reserved to the Board under the MLRA, because: (1) "under the MLRA, a reclamation procedure is one designed to minimize disruption during and after a mining operation" and Summit County's "ban stops certain mining from ever beginning"; (2) "reclamation procedures must occur on 'affected lands'" and "the cyanide and other reagents ban prevents the surface from becoming disturbed because it prohibits the mining operation from the start," thus "the ban does not occur on affected lands"; and (3) the ban "does not provide for establishment of plant cover, stabilization of soil, protection of water resources, or other reclamation measures as required by the MLRA." Colo. Mining Ass'n, 170 P.3d at 755 (internal quotations, citations, and emphasis removed).

We disagree with the court of appeals' judgment upholding Summit County's ordinance. In its 1993 amendments to the MLRA, see §§ 34-32-103(3.5), (4.9), -112.5, -116.5, the General Assembly assigned to the Board the authority to authorize and comprehensively regulate the use of toxic or acidic chemicals, such as cyanide, for mineral processing in mining operations, a field identified by the legislature that Summit County's ordinance would occupy, negating the Board's statutory role. Section 34-32-103(3.5)(a)(I) defines a "designated mining operation" as encompassing "a mining operation at which [t]oxic or acidic chemicals used in extractive metallurgical processing are present on site." Summit County's ordinance bans the use of such chemicals in all zoning districts in Summit County, thereby prohibiting mining methodologies the legislature has authorized the Board to authorize and regulate. Section 34-32-116.5(1)(a), (5) provide, in pertinent part, that "[a]n environmental protection plan shall be required for all designated mining operations" and that "[t]he [B]oard shall promulgate rules governing the form, content, and requirements of an environmental protection plan for any designated mining operation." Due to the sufficiently dominant state interest in mineral processing utilizing such chemicals, we find implied preemption in this case.

The Board has identified Summit County's ordinance as a reclamation standard, the setting of which is reserved to the Board under the MLRA. We may look to a state agency's interpretation of its own enabling statute, according deference when appropriate. See § 2-4-203, C.R.S. (2008); Colo. Dep't of Labor Employment v. Esser, 30 P.3d 189, 193 (Colo. 2001); CF I Steel, L.P. v. Pub. Utils. Comm'n, 949 P.2d 577, 585 (Colo. 1997). In the event of an irreconcilable conflict, a specific statutory provision applies over a more general provision. § 2-4-205, C.R.S. (2008). The application of section 2-4-205 may result in implied preemption of a county land use ordinance in the face of a controlling state statutory provision. Bainbridge, 929 P.2d at 698. We agree with the Board that Summit County's ordinance is impliedly preempted under the 1993 amendments to the MLRA.

1. Colorado's Mined Land Reclamation Act a. Pre-1993 Provisions of the MLRA

The Colorado General Assembly enacted the MLRA in 1976. The intent of the act is to foster the extraction of minerals, the reclamation of mined land, and the protection of human health, welfare, and the environment:

It is declared to be the policy of this state that the extraction of minerals and the reclamation of land affected by such extraction are both necessary and proper activities. It is further declared to be the policy of this state that both such activities should be and are compatible. It is the intent of the general assembly by the enactment of this article to foster and encourage the development of an economically sound and stable mining and minerals industry and to encourage the orderly development of the state's natural resources, while requiring those persons involved in mining operations to reclaim land affected by such operations so that the affected land may be put to a use beneficial to the people of this state. It is the further intent of the general assembly by the enactment of this article to conserve natural resources, to aid in the protection of wild-life and aquatic resources, to establish agricultural, recreational, residential, and industrial sites, and to protect and promote the health, safety, and general welfare of the people of this state.

§ 34-32-102(1), C.R.S. (2008) (emphasis added).

The General Assembly created the Board and the Office of Mined Land Reclamation in the Department of Natural Resources. § 34-32-105(1), C.R.S. (2008). The General Assembly granted the Board authority to promulgate standards for reclamation plans and to promulgate rules and regulations concerning mined land reclamation. §§ 34-32-106, -108, C.R.S. (2008). The statute also establishes a permitting program for mining operations. §§ 34-32-109, -112, C.R.S. (2008). The MLRA vests the Board with sole authority for reclamation permitting and standard setting:

No governmental office of the state, other than the board, nor any political subdivision of the state shall have the authority to issue a reclamation permit pursuant to this article, to require reclamation standards different than those established in this article, or to require any performance or financial warranty of any kind for mining operations.

§ 34-32-109(6) (emphasis added).

Although the word "reclamation" may seem to imply only post-mining activity, the General Assembly granted the Board broad authority to permit and regulate mining operations both during and after mining activities occur:

"Reclamation" means the employment during and after a mining operation of procedures reasonably designed to minimize as much as practicable the disruption from the mining operation and to provide for the establishment of plant cover, stabilization of soil, the protection of water resources, or other measures appropriate to the subsequent beneficial use of such affected lands. Reclamation shall be conducted in accordance with the performance standards of this article.

§ 34-32-103(13), C.R.S. (2008) (emphasis added).

b. 1993 Amendments to the MLRA

Through specific legislative amendments enacted in 1993, see §§ 34-32-103(3.5), (4.9), -112.5, -116.5, the General Assembly vested the Board with the authority to authorize the use of toxic or acidic chemicals, including cyanide, for mineral extraction in mining operations, under heavily regulated conditions. The General Assembly enacted these amendments in response to an environmental disaster at the Summitville Mine, a 1,400-acre site in Colorado's southern San Juan Mountains. See Aztec Minerals Corp. v. Romer, 940 P.2d 1025, 1027 (Colo.App. 1996). Under its pre-existing authority, the Board had permitted an open-pit gold mine that used a cyanide heap leach method. Id. The mine's system for environmental protection began to fail in 1987, causing the discharge of cyanide and acidic water into nearby ponds and creeks; these discharges ultimately killed nearly all living organisms in a seventeen-mile stretch of the Alamosa River. Id. at 1027-28. The operator of the Summitville Mine declared bankruptcy before cleanup could begin, causing the government and taxpayers to pay for remediation. Id. at 1028. The disaster drew international attention, and the U.S. Environmental Protection Agency ultimately placed the site on the National Priorities List, its register of the nation's most polluted sites. Id.

In response to the Summitville disaster, the Executive Director of the Colorado Department of Natural Resources convened a group including environmental representatives, mining industry representatives, and Board members to propose changes to the MLRA. That effort developed into Senate Bill 93-247, the purpose of which was to ensure that mining operations utilizing toxic or acidic chemicals would receive increased regulatory oversight under the MLRA.

The statutory amendments enacted by Senate Bill 93-247 created a new category of mining operations, Designated Mining Operations. §§ 34-32-103(3.5), -112.5. These include operations utilizing toxic or acidic chemicals, such as cyanide, for extractive metallurgical processing. § 34-32-103(3.5)(a)(I). Pursuant to its statutory authority, see §§ 34-32-103(4.9), -116.5, the Board has promulgated extensive rules governing Designated Mining Operations. See 2 Colo. Code Regs. § 407.1.

The statute and its implementing rules require applicants for Designated Mining Operations to submit and obtain approval of an Environmental Protection Plan, see § 34-32-116.5(5), that will "protect all areas that have potential to be affected by designated chemicals, toxic or acid-forming materials or acid mine drainage." 2 Colo. Code Regs. § 407.1, Rule 6.4.20. The Environmental Protection Plan must:

Fully describe the procedures for the disposal, decommissioning, detoxification or stabilization for all designated chemicals and toxic or acid-forming materials. Specifically describe measures to be taken to prevent any unauthorized release of pollutants to the environment. Include adequate reclamation and closure practices for such designated chemicals, toxic or acid-forming materials and how unauthorized discharge of acid mine drainage will be prevented.

2 Colo. Code Regs. § 407.1, Rule 6.4.20(6)(a).

In addition, the MLRA and its implementing regulations permit the Office of Mined Land Reclamation to inspect Designated Mining Operations during their construction and to require operators to take corrective actions. § 34-32-112.5; 2 Colo. Code Regs. § 407.1, Rule 7.4.1. The 1993 amendments to the MLRA also contain reporting requirements and financial safeguards intended to prevent another Summitville disaster. §§ 34-32-117, -118, -121.5, C.R.S. (2008).

In sum, by its 1993 amendments to the MLRA, the General Assembly granted the Board extensive authority to authorize and regulate mining operations proposing to utilize toxic or acidic chemicals for mineral extraction.

2. Relationship between MLRA and County Land Use Authority

The General Assembly has addressed the relationship between the MLRA and local land use ordinances in two sections of the MLRA. Those sections assume that the MLRA and land use ordinances can apply to mining operations in a compatible manner. The first section, which predates the 1993 amendments, provides:

The operator shall be responsible for assuring that the mining operation and the postmining land use comply with city, town, county, or city and county land use regulations and any master plan for extraction adopted pursuant to section 34-1-304 unless a prior declaration of intent to change or waive the prohibition is obtained by the applicant from the affected political subdivisions. Any mining operator subject to this article shall also be subject to zoning and land use authority and regulation by political subdivisions as provided by law.

§ 34-32-109(6).

The second provision of the MLRA addressing local ordinances, section 34-32-115(4)(c), was modified by the General Assembly in 1993, after the Summitville disaster. The provision previously prohibited the Board from granting a reclamation permit where "[a]ny part of the proposed mining operation, the reclamation program, or the proposed future use is contrary to the laws or regulations of this state or the United States." § 34-32-115(4)(c), C.R.S. (1992). The new language places the burden on the operator to demonstrate to the Board compliance with applicable MLRA and local requirements:

The board or the office shall grant a permit to an operator if the application complies with the requirements of this article. The board or the office shall not deny a permit if the operator demonstrates compliance with the following: . . . No part of the proposed mining operation, the reclamation program, or the proposed future use is or may be contrary to the laws or regulations of this state or the United States, including but not limited to all federal, state, and local permits, licenses, and approvals, as applicable to the specific operation.

§ 34-32-115(4), C.R.S. (2008) (emphasis added for new language); see also 2 Colo. Code Regs. § 407.1, Rule 6.4.20(4)(d).

Accordingly, the Board's rules and interpretations recognize that Designated Mining Operations are subject to the proper exercise of land use authority under applicable provisions of law. The Board has stated that:

Section 34-32-115(4), C.R.S., requires the Board to ensure that a proposed activity at a mine site will not be contrary to any local, state or federal law. This part of the Act refers to those local, state and Federal laws and regulations that pertain to protection of human health, property or the environment. The Board believes that all land-use decisions rest with other local, state, and federal land agencies.

Colorado counties are political subdivisions of the state. Bowen/Edwards, 830 P.2d at 1055; Bd. of County Comm'rs of Dolores County v. Love, 172 Colo. 121, 125, 470 P.2d 861, 862 (1970). Statutory counties derive their authority from the state; they possess only those authorities expressly conferred upon them by the state and those incidental implied powers reasonably necessary to carry out their expressly granted powers. Bowen/Edwards, 830 P.2d at 1055; Dolores County, 172 Colo. at 125, 470 P.2d at 862.

The General Assembly has expressly delegated to local governments broad powers to establish and enforce zoning and land use regulations. The Colorado Local Government Land Use Control Enabling Act, §§ 29-20-101 to -108, C.R.S. (2008), grants local governments, including counties, the authority to plan and regulate land use in numerous ways. Droste v. Bd. of County Comm'rs of County of Pitkin, 159 P.3d 601, 605-07 (Colo. 2007). Permissible exercises of land use authority under the Local Government Land Use Control Enabling Act include regulating development and activities in hazardous areas, protecting land from activities that would cause immediate or foreseeable material damage to significant wildlife habitat, and enacting regulations to provide for the orderly use of land and protection of the environment in a manner consistent with constitutional rights. § 29-20-104(1), C.R.S. (2008).

addition, the Colorado County Planning Code, §§ 30-28-101 to -139, C.R.S. (2008), expressly grants counties broad powers to "provide for the physical development" of unincorporated land within counties and to zone that land. § 30-28-102, C.R.S. (2008); see also Colo. State Bd. of Land Comm'rs v. Colo. Mined Land Reclamation Bd., 809 P.2d 974, 984 (Colo. 1991). County zoning codes may regulate:

the location, height, bulk, and size of buildings and other structures, percentage of lot which may be occupied, the size of lots, courts, and other open spaces, the density and distribution of population, the location and use of buildings and structures for trade, industry, residence, recreation, public activities, or other purposes, access to sunlight for solar energy devices, and the uses of land for trade, industry, recreation, or other purposes.

§ 30-28-111(1), C.R.S. (2008).

The Areas and Activities of State Interest Act ("HB 1041"), §§ 24-65.1-101 to -502, C.R.S. (2008), is another source of land use planning authority for counties. This act permits local governments, including counties, to designate as matters of state interest: "(a) Mineral resource areas; (b) Natural hazard areas; (c) Areas containing, or having a significant impact upon, historical, natural, or archaeological resources of statewide importance; and (d) Areas around key facilities in which development may have a material effect upon the key facility or the surrounding community." § 24-65.1-201, C.R.S. (2008). After designating such areas, local governments must develop guidelines for their administration; the local government may also adopt regulations concerning application of these guidelines. § 24-65.1-402, C.R.S. (2008). Prospective developers must apply to the local government for a permit in order to develop in designated areas of state interest. § 24-65.1-501, C.R.S. (2008).

The Board argues in its amicus brief that Summit County's ban on the use of cyanide and other toxic or acidic reagents for mineral processing is expressly or impliedly preempted by the MLRA. The Board further argues that the General Assembly granted the Board sole authority to set reclamation standards and did not grant statutory counties, like Summit County, the authority to set such standards. We agree with the Board's implied preemption contention, while also observing that Summit County retains considerable land use authority over the location and impacts of mining operations within the county.

3. Preemption Analysis

We have recognized that counties have broad land use authority, and we presume that zoning ordinances are valid. Bd. of County Comm'rs of Boulder County v. Thompson, 177 Colo. 277, 283, 493 P.2d 1358, 1361 (1972). Here, express preemption does not apply because section 34-32-115(4)(c)(I) of the MLRA recognizes the legitimate exercise of counties' land use authority.

However, counties' land use authority is not without bounds. Zoning provisions must be reasonable and promote the public welfare. Di Salle v. Giggal, 128 Colo. 208, 212-13, 261 P.2d 499, 501 (1953). Courts examine with particular scrutiny those zoning ordinances that ban certain land uses or activities instead of delineating appropriate areas for those uses or activities. See, e.g., Combined Commc'n Corp. v. City and County of Denver, 189 Colo. 462, 466-67, 542 P.2d 79, 82-83 (1975) (prohibition of billboards throughout Denver was unreasonable and exceeded City and County of Denver's zoning authority); Exton Quarries, Inc. v. Zoning Bd. of Adjustment of West Whiteland Twp., 425 Pa. 43, 228 A.2d 169, 179 (1967) ("constitutionality of zoning ordinances which totally prohibit legitimate businesses such as quarrying from an entire community should be regarded with particular circumspection").

Although we did not find the existence of an irreconcilable conflict constituting preemption in Bowen/Edwards, we observed that, if the county's regulations were to "impose technical conditions on the drilling or pumping of wells under circumstances where no such conditions are imposed under the state statutory or regulatory scheme, or to impose safety regulations or land restoration requirements contrary to those required by state law or regulation," those regulations could impermissibly conflict with the state interest. 830 P.2d at 1059-60.

We concluded in Voss that a home rule city's ban against drilling would contravene the state's interest in efficient development of oil and gas resources. 830 P.2d at 1067. In addition, given the manner in which oil and gas tends to pool underground, a ban in one jurisdiction could increase the costs of drilling a pool that underlies both the jurisdiction with a ban and a neighboring jurisdiction without a ban. Id. at 1067-68. In holding that the state's interest took precedence over the local ban, we took care to emphasize that local land use regulations could be consistent with the Oil and Gas Conservation Act if the local and state regulations could be harmonized. 830 P.2d at 1068-69. We cited our previous holding in National Advertising Co. v. Department of Highways, 751 P.2d 632, 635 (Colo. 1988), for the proposition that "a home-rule city can exercise control over outdoor advertising within its borders under its zoning authority only to the extent that the local ordinance does not materially impede the significant state goals expressed in the Outdoor Advertising Act." 830 P.2d at 1068. We find Voss particularly instructive because, if a home rule city may not enact a ban prohibiting what the state agency may authorize under the statute, surely a statutory county may not do so.

We recognize common themes in Bowen/Edwards and Voss: (1) the state has a significant interest in both mineral development and in human health and environmental protection, and (2) the exercise of local land use authority complements the exercise of state authority but cannot negate a more specifically drawn statutory provision the General Assembly has enacted.

Examining the Board's comprehensive authority over Designated Mining Operations, we conclude that Summit County's ban on the use of cyanide or other toxic/acidic ore-processing reagents in heap or vat leach applications exceeds its statutory authority in a field the General Assembly identified and granted the Board authority to permit and regulate, i.e., the use of toxic or acidic chemicals or reagents in mining operations for mineral processing. We reach this conclusion for three principal reasons: (1) the ordinance impedes the MLRA's goal of encouraging mineral development while protecting human health and the environment; (2) the ordinance is inconsistent with both the General Assembly's decision to authorize mining operations that use chemicals for extraction and the resulting Board-regulated permitting regime for Designated Mining Operations; and (3) state statutes and canons of statutory construction require that we resolve the conflict between the MLRA and Summit County's ban ordinance in favor of the MLRA. In so ruling, we also recognize that Summit County retains authority to exercise its delegated land use authority, consistent with the General Assembly's intent.

We accord significant weight to a legislative declaration that a given matter is of statewide interest, Nat'l Adver., 751 P.2d at 635, and we construe statutes to give effect to such a legislative purpose. Flood v. Mercantile Adjustment Bureau, 176 P.3d 769, 772 (Colo. 2008). Here, the General Assembly stated that extraction of minerals is "necessary and proper," and the General Assembly "encourage[d] the development of an economically sound and stable mining and minerals industry" along with "encourag[ing] the orderly development of the state's natural resources." § 34-32-102. In so providing, the General Assembly recognized that valuable mineral deposits exist where natural forces have placed them, and the mineral industry depends on being able to conduct safe and effective operations to extract those minerals, including from tailings left over from prior mining operations. The MLRA sets forth a sufficiently dominant state interest in the controlled use of chemicals to process valuable minerals.

A patchwork of county-level bans on certain mining extraction methods would inhibit what the General Assembly has recognized as a necessary activity and would impede the orderly development of Colorado's mineral resources. See id. It would prohibit the recovery of minerals in areas where operations using cyanide or other chemicals for mineral extraction can be conducted in an environmentally protective manner.

Though counties have broad land use planning authority, that authority does not generally include the right to ban disfavored uses from all zoning districts. See, e.g., Combined Commc'n Corp., 189 Colo. at 466-67, 542 P.2d at 82-83. Rather, local land use authority is typically exercised by designating appropriate areas for different land uses and placing conditions on those uses. The General Assembly did not contemplate that statutory counties could entirely prohibit a broad category of mining operations by ordinance. When it was considering its 1993 MLRA amendments in the wake of the Summitville disaster, the General Assembly had the option of banning heap or vat leach operations using cyanide, the mineral processing technique used at Summitville, squarely before it. Instead, it chose to vest in the Board an enhanced program to manage mineral processing methods that utilize acidic or toxic chemicals. See § 34-32-112.5. Utilizing its expertise, the Board has exercised this authority, see § 34-32-116.5, by permitting and regulating Designated Mining Operations using cyanide and other toxic/acidic ore-processing reagents in heap or vat leach applications, the very processes Summit County bans by its ordinance. See 2 Colo. Code Regs. § 407.1.

While they do not bind our construction of the applicable law, we consult and take into account the implementing agency's guidance, rules, and determinations, if they accord with the constitutional and statutory provisions they implement. Washington County Bd. of Equalization v. Petron Dev. Co., 109 P.3d 146, 150 (Colo. 2005). In reviewing the proper construction of a statute de novo, we may accord deference to the agency's interpretation of its statute, but we are not bound by that interpretation. Lobato v. Indus. Claim Appeals Office, 105 P.3d 220, 223 (Colo. 2005).

In light of its statutory authority, the Board construes Summit County's ordinance as a reclamation standard because section 34-32-103(13) defines "reclamation" to include "procedures reasonably designed to minimize as much as practicable the disruption from the mining operation." The Board points out that "a ban on a type of mining operation, such as the one Summit County imposed, is the most extreme way to minimize disruption caused by a mining operation."

The Board's interpretation that it has statutory authority to promulgate and enforce reclamation standards for Designated Mining Operations utilizing chemicals for mineral extraction, to the exclusion of conflicting county ordinances purporting to set reclamation standards, is long-standing and not merely a litigation position. The specific statutory authorization, sections 34-32-112.5, -116.5, as implemented by rules of the Board, 2 Colo. Code Regs. § 407-1, addresses the use of "Designated Chemicals," 2 Colo. Code Regs. § 407.1, Rule 1.1(13), in Designated Mining Operations, 2 Colo. Code Regs. § 407-1, Rule 1.1(14), for "Extractive Metallurgical Processing," 2 Colo. Code Regs. § 407.1, Rule 1.1(18), Rule 6.4.20(6)(b)(i), in "leach facilities" or a "heap leach pad," 2 Colo. Code Regs. § 407.1, Rule 6.4.20(c)(i).

In the 1993 amendments, the General Assembly extended the Board's reclamation standard-setting authority to designated chemicals, mining techniques, and mining operations. §§ 34-32-112.5, -116.5. The Board construed and implemented that authority in adopting the above cited rules set forth in 2 Colo. Code Regs. § 407.1, including Rule 6.4.20, which requires any applicant for a Designated Mining Operation permit to submit an extensive Environmental Protection Plan addressing the protection of ground water and surface water. That document must include a narrative description or plan that "describes how all designated chemicals used in the extractive metallurgical process will be handled during active mining operations, during periods of Temporary Cessation, and disposed or detoxified at the conclusion of operations so as to comply with all applicable environmental protection and reclamation standards and regulations." 2 Colo. Code Regs. § 407.1, Rule 6.4.20(6)(b)(i).

We factor the Board's interpretation of the MLRA and its construction of Summit County's ordinance into our implied preemption analysis. We traditionally take into account an agency's interpretations on issues encompassed within its expertise. See, e.g., Huddleston v. Grand County Bd, of Equalization, 913 P.2d 15, 17 (Colo. 1996); Colo. State Personnel Bd. v. Dep't of Corrs., 988 P.2d 1147, 1150 (Colo. 1999). The Board is the expert agency established by the General Assembly to promulgate mining operation permit regulations and reclamation standards. As such, its expertise includes identifying what is or is not a reclamation standard. It has identified Summit County's ordinance as a reclamation standard, reserved to the Board under its enabling statute. Taking into account the Board's construction of its enabling act, we agree with the Board that the MLRA impliedly preempts the county's ordinance.

Section 30-15-411 provides that "[n]o county shall adopt an ordinance that is in conflict with any state statute." Under the MLRA, the General Assembly gave the Board authority to set reclamation standards. The term "reclamation" includes:

the employment during and after a mining operation of procedures reasonably designed to minimize as much as practicable the disruption from the mining operation and to provide for the establishment of plant cover, stabilization of soil, the protection of water resources, or other measures appropriate to the subsequent beneficial use of such affected lands.

§ 34-32-103(13) (emphasis added). The statute defines the term "affected land" as "the surface of an area within the state where a mining operation is being or will be conducted, which surface is disturbed as a result of such operation." § 34-32-103(1.5).

The 1993 statutory amendments granted the Board authority to minimize potential disruption to the environment from Designated Mining Operations before mining commences. By definition of the General Assembly, "'Designated Mining Operation' means a mining operation at which [t]oxic or acidic chemicals used in extractive metallurgical processing are present on site. . . ." § 34-32-103(3.5). Section 34-32-103(4.9) requires an applicant for a Designated Mining Operation to submit an Environmental Protection Plan to the Board. When considering the application, the Board determines whether the Plan adequately addresses potential adverse impacts from leach faculties or heap leach pads and whether the Plan "protect[s] the public and the environment from the adverse effects of designated chemicals, acid or toxic producing materials or acid mine drainage. . . ." 2 Colo. Code Regs. § 407.1, Rule 6.4.20(1)(b).

A prospective mine operator must obtain approval of a reclamation plan in order to obtain an operating permit. § 34-32-112. Reclamation plans must include standards for grading, impoundments, handling of acid-forming or toxic-forming material, and the like. § 34-32-116. Once a permit has been issued, but before the mine begins operation, the Board may require inspection and certification of the environmental protection system of a Designated Mining Operation. The Board may prohibit further construction or operation until inspection and certification requirements have been satisfied. § 34-32-112.5(4)(a).

These statutory and regulatory provisions construed as a whole demonstrate that the General Assembly has identified the field of chemical use in mining operations for mineral processing as a matter of significant and dominant state interest. Contrary to the General Assembly's intent, the court of appeals' judgment would allow statutory counties to categorically prohibit mining operations that are subject to the Board's Designated Mining Operation rules, eviscerating the Board's reclamation standard-setting authority and its role in permitting and regulating Designated Mining Operations. We do not read statutes in contravention of the General Assembly's purpose. See Flood, 176 P.3d at 772. Instead, we examine the actual language the General Assembly has employed, reconcile conflicts if possible, and give effect to specific statutory provisions over general ones. Anderson v. Longmont Toyota, Inc., 102 P.3d 323, 326-27 (Colo. 2004); Bainbridge, 929 P.2d at 707.

In Bainbridge, 929 P.2d at 698, 703-04, we examined a statutory county's assertion of land use authority and concluded that a specific statutory provision concerning payment of school impact fees by developers controlled over the county's broad land use authority. In the case before us, we conclude that the Summit County ordinance similarly runs afoul of the canon of statutory construction that, in the event of irreconcilable conflict, specific provisions trump general provisions. § 2-4-205. The ordinance also contravenes section 29-20-107, which provides that other procedural or substantive requirements for land use planning or regulation provided by state law shall control over local regulations. See Droste, 159 P.3d at 607 (section 29-20-107 "codif[ies] the familiar rule that a specific provision controls over a more general provision").

Application of the preemption analysis we utilized in Voss, Ibarra, Banner Advertising, and other cases leads to the conclusion that Summit County's ban on the use of cyanide or other toxic or acidic reagents for mineral processing impermissibly conflicts with the MLRA, resulting in the implied preemption of the Summit County ordinance. Implied preemption occurred here because the General Assembly expressed a sufficiently dominant interest by assigning to the Board the field of the use of chemicals and other toxic and acidic reagents in mining operations for mineral processing. In Ibarra, we utilized implied preemption to void a local home rule ordinance upon finding that the state's interest was "sufficiently dominant" to override the home rule city's ordinance. 62 P.3d at 163. In Banner Advertising,

868 P.2d at 1081-83, we found implied preemption because the local ordinance banned what the federal agency with administrative authority could authorize. A parallel situation exists here, in that the county bans what the Board may authorize.

Thus, Summit County's ban on the use of chemicals, such as cyanide, for mineral processing is not enforceable. In so holding, we emphasize that this ordinance is unusual in that it bans an activity the state statute authorizes. We do not have before us in this case a county land use ordinance that can be harmonized with the MLRA. Instead, Summit County's ordinance would elevate broad land use powers, intended by the General Assembly to be exercised in concert with the MLRA, over the Board's reclamation permitting and standard-setting authority over the use of chemicals for mineral processing.

Our decision does not prevent statutory counties from considering and implementing regulations that are valid under the Local Government Land Use Control Enabling Act, the County Planning Act, and the Areas and Activities of State Interest Act. The General Assembly has provided authority for county regulation of mine siting and impacts consistent with the MLRA, as provided in section 34-32-109(6), and section 34-32-115(4)(c)(I).

III.

Accordingly, we reverse the judgment of the court of appeals in favor of the district court's judgment invalidating Summit County's ordinance.

Justice EID concurs in the judgment, and Justice COATS joins in the concurrence.

Justice MARTINEZ dissents.