The two questions raised in this appeal are (1) whether the control of outdoor advertising signs located within a home-rule municipality along roads of the state highway system is a matter of exclusively local or exclusively statewide concern, or is a matter of mixed local and statewide concern, and (2) whether the State Department of Highways (department) should be es-topped from denying a permit for an outdoor advertising sign because a home-rule municipаlity already had issued a building permit for the sign. The district court held that the control of outdoor advertising is a matter of mixed statewide and local concern and that, consequently, the permit provisions of the Outdoor Advertising Act, §§ 43-1-401 to -420, 17 C.R.S. (1984 & 1987 Supp.), and the Roadside Advertising Regulations promulgated by the department, 2 Colo.Code Regs. § 601-3 (1983), superseded a conflicting provision of the city of Colorado Springs sign code. In so holding, the court implicitly rejected the claim that the department was estopped from challenging the validity of the sign on the basis of a sign permit issued pursuant to the municipal sign code. We affirm the judgment of the district court.
I.
This action was commenced in the District Court of El Paso County by National Advertising Company (National), Boychuk Construction, Inc., and Boychuk’s president, Edgar Dill, against the department and three of its officers charged with the enforcement of the Outdoor Advertising Act. The complaint sought declaratory and injunctive relief against the dеpartment and its employees on the basis that the Home Rule Amendment to the Colorado Constitution, Colo. Const, art. XX, rendered the provisions of the act void and unenforceable against National’s sign located within the home-rule municipality of Colorado Springs. The complaint raised the alternative claim that the department should be estopped from enforcing the act because the city of Colorado Springs had issued to National a building permit for thе sign. 1 The department and its employees filed an answer to the complaint. The parties then agreed to submit the case for trial to the court on the basis of the following stipulated facts.
Colorado Springs is a home-rule city. In its charter, the city has reserved to itself legislative, executive, and judicial powers over “all matters of local and municipal government,” Charter, City of Colorado Springs, art. I, § 2(e) (1980), and, as well, the power “to supersede any law of this state, now or hereafter enforced, insofar as it applies to local or municipal matters,” id. at art. XIX, § 158.
In August 1983, National applied to the Pikes Peak Regional Building Department, which was the delegated licensing entity for building activities within the city of Colorado Springs, for a building permit to erect a sign. The building permit was issued, and on September 8, 1983, National leased from Boychuk Construction a parcel of land adjacent to State Highway 83, located within the municipal boundaries of Colоrado Springs, and in an area zoned for industrial or commercial uses subsequent to January 1, 1970. The lease between National and Boychuk Construction obligated National to pay Boychuk $18,000 for the leased premises over a ten-year period. After it obtained the building permit for the sign, National leased to U.S. Home Corporation for one year the advertising faces on the sign structure for $22,000. National then erected an outdoor advertising sign, in accordance with its building permit, at a cost of approximately $25,000.
At no time did National apply to the department for a sign permit, and, according to the stipulation, even if National had made such an application, the department *634 would not have issued a permit due to the fact that the National sign exceeded the size limitations prescribed by the Outdoor Advertising Act. See § 43-l-404(l)(e)(I)(A), 17 C.R.S. (1984) (sign located along primary or secondary highways in areas zoned for industrial or commercial uses may not be larger than 150 square feet); 2 Colo.Code Regs. § 601-3(VII)(B)(l)(b) (1983) (same). On January 9, 1984, the department served National with a “Notice of Violation of the Outdoor Advertising Act,” based in part on the size of its sign. 2
In ruling on the stipulated facts, the district court began its analysis by noting that in matters of both statewide and local concern a state statute and a municipal ordinance may coexist as long as they do not conflict, but that if they do conflict, the state statute supersedes the municipal ordinance.
See, e.g., Delong v. City and County of Denver,
In appealing the judgment, National, relying on the Home Rule Amendment in Article XX of the Colorado Constitution, initially claims that the control of advertising signs located within a home-rule municipality along roads of the state highway system is a matter of exclusively local concern and thus not subject to the regulatory scheme created by the Outdoor Advertising Act. 3 National next argues that the issuance of a permit to National, pursuant to the Colorado Springs sign code, estops the department from enforcing the Outdoor Advertising Act and Roadside Advertising Regulations against National’s sign.
II.
We first consider National’s claim that the control of outdoor advertising signs located within a home-rule municipality along roads of the state highway system is a matter of exclusively local concern and is thus exempt from the provisions of the Outdoor Advertising Act. The express purpose of Article XX of the Colorado Constitution is “to grant and confirm to the people of all municipalities coming within its provisions the full right of self-govem
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ment in both local and municipal matters.” Colo. Const, art. XX, § 6. It is well established that in a matter of exclusively local concern, a charter or ordinance provision of a home-rule municipality supersedes a conflicting state statute; in a matter of exclusively state concern, however, a state statute supersedes a conflicting charter or ordinance provision of a home-rule municipality; and, finally, in a matter of mixed local and statewide concern, a charter or ordinance provision of a home-rule municipality may coexist with a state statute as long as there is no conflict, but in the event of a conflict the state statute supersedes thе conflicting provision of the charter or ordinance.
E.g., City and County of Denver v. Colorado River Water Conservation District,
A.
There is no litmus-like indicator for resolving whether a matter is of local, statewide, or mixed concern. We have made such determinations on an ad hoc basis, taking into consideration the facts of each case.
E.g., Colorado River Water Conservation District,
Although “zoning” is not expressly enumerated in Article XX of the Colorado Constitution as a specific power of municipal self-government,
cf. City of Thornton v. Farmers Reservoir & Irrigation Co.,
B.
The General Assembly expressly declared that its purpose in enacting the Out *636 door Advertising Act was “to control the existing and future use of advertising devices in areas adjacent to the state highway system in order to protect and promote the health, safety, and welfare of the traveling public and the people of Colorado” and further stated that “such purposes are declared to be ‘of statewide cоncern.’ ” § 43 — 1—402(l)(a), 17 C.R.S. (1984). The General Assembly then enumerated the following “substantial state interests” which it expressly intended to further by the act:
(I) Protection of the public investment in the state highway system;
(II) Promotion of safety upon the state highway system;
(III) Promotion of the recreational value of public travel;
(IV) Promotion of public pride and spirit both on a statewide and local basis;
(V) Preservation and enhancement of the natural and scenic beauty of this state;
(VI) Broadening the economic well-being and general welfare by attracting to this state tourists and other travelers;
(VII) Providing the traveling publiс with information as to necessary goods and services in the immediate vicinity of the traveler;
(VIII) Protection and encouragement of local tourist-related businesses for the general economic well-being of this state;
(IX) Insuring that Colorado receives its full share of funds to be apportioned by the congress of the United States for expenditures on federal-aid highways.
§ 43-l-402(l)(a), 17 C.R.S. (1984). In keeping with these “substantial state interests,” the statutory scheme, as pertinent here, allows for thе erection and maintenance of outdoor advertising signs located along primary and secondary highways in areas zoned for industrial or commercial uses under authority of state law on or after January 1, 1970, provided that such signs are no larger than 150 square feet and subject to the additional proviso, which is of critical importance to this case, that the department issue a permit for the signs. §§ 43-l-404(l)(e)(I)(A) and 43-1-407(l)(c), 17 C.R.S. (1984). The Roadside Advertising Regulations, which were promulgated by the dеpartment pursuant to its statutory authority, § 43-1-415(1), 17 C.R. S. (1984), require a permit for any outdoor advertising sign adjacent to the state highway system in areas zoned for industrial or commercial uses. 2 Colo.Code Regs. § 601-3(VII) (1983). “Areas adjacent to the state highway system” include “areas which are visible from the main-traveled way and within 660 feet of the nearest edge of the right-of-way.” Id. § 601-3(IV)(E).
C.
While a home-rule municipality obviously has an interest in controlling outdoor advertising signs within its municipal borders, the legislative declaration of purpose in the Outdoor Advertising Act makes clear that the state also has an interest in achieving and maintaining those safety, recreational, aesthetic, and fiscal goals which the act is intended to further. Vesting a home-rule municipality with exclusive control over outdoor advertising devices located within the municipality along roads of the state highway system would materially impede, if not destroy, any prospect of achieving those goals. The interests of thе state in controlling outdoor advertising signs located within a home-rule municipality along roads of the state highway system are not insubstantial and, at the risk of understatement, are entitled to be valued no less than any interest of a home-rule municipality in controlling these same signs within its municipal borders.
In urging us to hold that the control of outdoor advertising devices located within a home-rule municipality along roads of the state highway system is a matter of exclusively local concern, National places great reliance on certain regulations promulgated under the federal Highway and Beautification Act of 1965, 23 U.S.C. § 131 (1982). In particular, National relies on 23 C.F.R. § 750.706(c)(2) (1987), which permits control of outdoor advertising devices by local zoning authorities when state law permits such local control and the state has entered into an agreement to that effect with the United States Department of Transporta
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tion. In 1971, the department did enter into an agreеment with the United States Department of Transportation, in which Colorado agreed to effectively control the erection and maintenance of outdoor advertising signs in the state in accordance with the terms of the agreement.
See Orsinger Outdoor Advertising, Inc. v. Department of Highways,
The regulations established by local zoning authority may be either more restrictive or less restrictive than the criteria contained in the agreement, unless State law or regulations require equivalent or more restrictive controls.
2 C.F.R. § 750.706(c)(2) (1987) (emphasis added).
The Outdoor Advertising Act, in our view, contemplates equally restrictive or more restrictive local controls in keeping with the statutory goals and state interests sought to be achieved by the act. Section 43-1-416, 17 C.R.S. (1984), states:
Nothing in this [act] shall be construed to prevent use of zoning powers and establishment of stricter limitations or controls on advertising devices by any municipality or county within its boundaries so long as such limitations or controls do not jeopardize the receipt by the state of its full share of federal highway funds.
(Emphasis added).
We recently acknowledged that one of the primary purposes of the act was to make certain that Colorado receives its full sharе of federal-aid highway funds appropriated by the United States Congress.
Pigg v. State Department of Highways,
Finally, while we have recognized that maintaining Colorado’s eligibility for federal-aid highway funds was one of the primary purposes of the Outdoor Advertising Act, we hasten to add that the act was also enacted to further other significant state interests. Permitting a home-rule municipality to establish a regulatory scheme for outdoor advertising signs less restrictive than required by the Outdoor Advertising Act not only would impair the prospect of Colorado’s continued eligibility for federal-aid highway funding but also would run the risk of unduly depreciating the importance of those other “substantial state interests” enumerated in the Outdoor Advertising Act. See § 43-l-402(l)(a)(I-IX), 17 C.R.S. (1984). We accordingly hold that the control of outdoor advertising devices within a home-rule municipality along roads of the state highway system is a matter of mixed statewide and local concern.
D.
We now consider whether the regulatory scheme adopted by Colorado Springs conflicts with the provisions of the Outdoor Advertising Act. A conflict between an ordinance and a statute can be found “where the ordinance authorizes the doing of acts which the statute prohibits.”
Vick v. People,
In the instant case, the parties have stipulated that the city of Colorado Springs, through the entity to which it delegated its powers to license and permit building activities, issued a permit to National to erect the disputed sign, but that the department would not have issued a sign permit to National because the erection of the sign was in violation of the provisions of the Outdoor Advertising Act and the Roadside Advertising Regulations adopted by the department. Since the sign code of Colorado Springs thus authorizes what the Outdoor Advertising Act and the Roadside Advertising Regulations prohibit, a conflict is manifest. Under these circumstances, the permit requirements of the Outdoor Advertising Act and the Roadside Advertising Regulations clearly supersede any conflicting provisions of the sign code of Colorado Springs pursuant to which National was issued a permit.
III.
We turn now to National’s claim that the decision of Colorado Springs to issue a sign should estop the department from enforcing the Outdoor Advertising Act against National’s sign. We considered a similar claim in
National Advertising Company v. Department of Highways,
The duties and responsibilities of Arapahoe County are therefore separate and distinct from those of the Department. National cannot have reasonably relied on issuance of a county permit in concluding that its sign complied with the requirements of the state Outdoor Advertising Act. See Colorado Water *639 Quality Control Comm’n v. Town of Frederick,641 P.2d 958 , 964 (Colo.1982) (“Estoppel may be available against a governmental agency to prevent injustice ¾/the plaintiffs can show reasonable reliance on agency action.” (emphasis supplied)). Thus, National’s government es-toppel claim lacks merit.
Id. at 1043-44 (emphasis in original). We find this reasoning dispositive of the estop-pel issue raised here. We thus conclude that, under the circumstances of this case, the department is not estopped from enforcing the Outdoor Advertising Act against the sign erected by National.
The judgment of the district court is affirmed.
Notes
. National originally included in its complaint claims for compensatory and exemplary damages against the defendants, but subsequently stipulated to the withdrawal of these claims.
. While the notice cited various provisions of the Outdoor Advertising Act and the Roadside Advertising Regulations as the source of the alleged violation, the parties stipulated that the sign structure was in an area zoned for industrial or commercial uses subsequent to January 1, 1970, and was impermissible under the act and the regulations. The parties also stipulated that National, in addition to not requesting a sign permit from the department, did not request a hearing on the alleged violation. The stipulation recites that “[a] permit would not have been issued by the ... Department of Highways because of the reasons specified in [the Notice of Violation], and the Department of Highways would not issue a permit unless so directed by a court of competent jurisdiction.” A motion to dismiss Natiоnal’s complaint based on its failure to exhaust administrative remedies was denied by the district court on the basis that National’s request for administrative relief would have been futile. This aspect of the district court’s ruling is not before us, and we express no view on the propriety of such ruling.
. Because National’s challenge to the applicability of the Outdoor Advertising Act to its sign is based on Article XX of the Colorado Constitution, jurisdiction over this appeal properly lies in this court rather than in the court of appeals. See § 13 — 4—102(l)(b), 6A C.R.S. (1987).
. We note that the Colorado Court of Appeals in
Moore v. City of Boulder,
. Colorado entered into the 1971 agreement pursuant to the authority granted the department to enter into such agreements in order to "carry out the national policy concerning outdoor advertising adjacent to the interstate system and federal-aid primary highways and to accept any allotment of funds by the United States, or any department or agency thereof, appropriated in furtherance of federal-aid highway legislation." § 43-1-415(3), 17 C.R.S. (1984).
. The 1971 agreement applies to various areas including "[a]ll zoned commercial and industrial areas within 660 feet of the nearest edge of the right-of-way of all portions of the Federal-aid primary system within the State of Colorado in which outdoor advertising signs may be visible from the main-traveled way of said system.” A "Federal-aid primary highway" is defined in the agreement as “any highway within that portion of the State highway system as designated, or as may hereafter be so designated by the State, which has been approved by the Secretary of Transportation pursuant to subsection (b) of Section 103 of Title 23, United States Code.” The agreement provides that when a bona fide local zoning authority "adopts regulations which include the size, lighting, and spacing of outdoor advertising, the State may so notify the [Federal Highway] Administrator and control of outdoor advertising in commercial or industrial zones within the geographical jurisdiction of said authority will transfer to subsection A of this section." Subsection A, to which the "local control” provision refers, states:
In zoned commercial and industrial areas, the State may notify the Administrator as notice of effective control that there has been established within such areas regulations which are enforced with respect to the size, lighting, and spacing of outdoor advertising signs consistent with the intent of the Highway Beautification Act of 1965 and with customary use. In such areas, the size, lighting, and spacing requirements set forth below shall not apply.
