[¶ 1.] In this mandamus action on alleged nuisance and zoning ordinance violations, we affirm the circuit court’s judgment denying relief.
Background
[¶ 2.] Defendant Tour Ice began its retail business in 1978. Consisting of a mobile home and garage, it was first located at 420 South Henry Street, Pierre, South Dakota, one block west of its current site at 425 South Central Avenue. The business moved to the latter address in 1991, when its new icé plant was completed. Since its inception, it has operated for thirty-two years in a zone classified as the central business district. Now, at the rate of 100,000 pounds a day, it produces, packages, and sells cube and block ice to retail establishments. Refrigerated trucks deliver its ice products within a 140-mile radius. In 1992, Stephen Ellwein, Inc., purchased the business.
[¶ 3.] Plaintiff Judith A. Atkinson lives on the second floor of a twelve-unit apartment building at 420 South Central Avenue, in the same business district. She has resided there since December 1996. Her apartment has three windows facing the Tour Ice facilities across the street. She prefers to keep all her windows open throughout the year, including the winter months. When the weather is cold, the temperature in her apartment is still hotter than she prefers, and opening her windows is her only solution. Besides enjoying the fresh air for its own sake, she does not feel that she should have to close her windows merely to reduce the noise coming from Tour Ice.
[¶ 4.] Atkinson finds the noise intolerable, nonetheless. According to her, “the general sound level of the compressor and fans running are equal to a vacuum cleaner or a freight _ train running through [her] bedroom.” Tour Ice begins its business day early in the morning when its delivery trucks start up, load ice, and depart for the day’s destinations. This surge of noise wakes Atkinson up, but she also objects to the constant, twenty-four-hour a day noise coming from the compressors, cooling fans, cooling towers, and ice augers. Some of the noises are disturbing because they are irregular, like the compressor that kicks on and off every ten to twelve minutes. Although Tour Ice attempted to remedy, or at least muffle, its various machine noises, Atkinson insists that the noise has only increased over time because of expansion. Using a sound meter she purchased over the Internet, Atkinson measured the noise level in her bedroom at seventy to seventy-five decibels when the compressor and fans are operating. More noise occurs when trucks parked outside the facility run their cooling units all night.
[¶ 5.] The classification of the current central business district was adopted in 1970 through the Pierre City Ordinances. The purpose of the 1970 ordinance was to provide for the widest range of retail and service establishments in the area. In 1999, however, the city adopted a more detailed statement of purpose for the central business district, narrowing the range of permitted uses.1 The apartment build*794ing Atkinson lives in was permitted in the district as a conditional use.
[¶ 6.] Since Ellwein’s purchase, Tour Ice has not changed the nature of its business, although it has expanded its infrastructure. In 1993, the city granted Ell-wein a building permit for an addition. In 1997, Ellwein purchased lots adjacent to the existing building, and, at a cost of $100,000, a new metal building was attached to the existing structure. At that time, the city again issued a building permit, allowing Ellwein to add on to the building. Improvements to the site included the installation of additional cooling fans, a refrigerator and compressor unit, and two large ice making machines. Along with its expansion, the company’s activities have created an increased level of noise. Under the 1999 zoning ordinance amendments, however, Tour Ice was considered a permitted use because it was a longstanding business in the area. Accordingly, the company was not required to apply to the city for non-conforming use status by obtaining a variance for either its use or its building.
[¶ 7.] After its second building addition in 1997, Atkinson complained directly to Tour Ice’s management. Then she delivered a petition to the owner signed by eight neighbors. In response, the company’s attorney sent Atkinson a letter stating that the business conforms to the city’s zoning ordinances. Subsequently, the city issued its own letter, explaining that the company was operating as a preexisting business within the zoning district. Atkinson protested to the Pierre City Council, but to no avail.
[¶ 8.] Atkinson brought suit against Tour Ice alleging that its business activities constitute a nuisance and that it violates city zoning laws. She sought to prohibit the business “from operating a manufacturing plant, a storage depot, and a wholesale business!.]” She also asked for an injunction against noise during non-business hours. Her suit against the city sought a writ of mandamus to make the city enforce its ordinances against Tour Ice. In trial, the company’s owner, Stephen Ellwein, conceded, “Just so ... everybody understands what we are talking about, we manufacture ice. I mean, that’s a given.” Following a court trial, the circuit court found in favor of Tour Ice and the city, ruling that the business was a permitted preexisting use because it predated the 1999 ordinance and was in compliance with the 1970 zoning ordinance. Atkinson now appeals, raising the following issues for our review: (1) whether the circuit court’s determination that Tour Ice’s activities did not constitute a nuisance was palpably unreasonable; (2) whether the zoning ordinances *795were properly interpreted; (3) and whether the circuit court abused its discretion in denying her requested writ of mandamus.
Standard of Review
[¶ 9.] Because cities have the power to declare nuisances, their decisions should be upheld unless they are “ ‘palpably unreasonable.’ ” Union County v. Hoffman, 512 N.W.2d 168, 170 (S.D.1994) (quoting Town of Colton v. South Dakota Cent. Land Co., 25 S.D. 309, 312-13, 126 N.W. 507, 508 (1910)); SDCL 9-29-13. We will not set aside a trial court’s findings of fact unless they are clearly erroneous. Hoffman, 512 N.W.2d at 170. “ ‘A finding is “clearly erroneous” when after reviewing all of the evidence, we are left with a definite and firm conviction that a mistake was made.’” Id. (citation omitted).
[¶ 10.] “We interpret zoning laws according to the rules of statutory construction and any rules of construction included in the enactments themselves.” City of Marion v. Rapp, 2002 SD 146, ¶ 5, 655 N.W.2d 88, 90 (citing Cole v. Bd. of Adjustment of Huron, 2000 SD 119, ¶ 7, 616 N.W.2d 483, 485; Cordell v. Codington County, 526 N.W.2d 115, 117 (S.D.1994)). “The interpretation of an ordinance presents a question of law reviewable de novo.” Id. (referencing Even v. City of Parker, 1999 SD 72, ¶ 8, 597 N.W.2d 670, 673). We review the grant or denial of a writ of mandamus for abuse of discretion. Lang v. Western Providers Physician Org., Inc., 2004 SD 107, ¶ 7, 688 N.W.2d 403, 406 (citing Black Hills Cent. R.R. Co. v. City of Hill City, 2003 SD 152, ¶ 9, 674 N.W.2d 31, 34).
Analysis and Decision
A. Nuisance
[¶ 11.] Atkinson argues that the “inaction by the City of Pierre towards the noise created by Tour Ice [is] palpably unreasonable.” She maintains that the business should be declared a nuisance. Its operation, Atkinson asserts, unreasonably violates, invades, and interferes with her private use and enjoyment of her leasehold interest in her apartment.
[¶ 12.] “[A] claim for nuisance may be brought under statutory or common law nuisance theories.” Collins v. Barker, 2003 SD 100, ¶ 16, 668 N.W.2d 548, 553. Nuisance is defined in SDCL 21-10-1:
A nuisance consists in unlawfully doing an act, or omitting to perform a duty, which act or omission either:
(1) Annoys, injures, or endangers the comfort, repose, health, or safety of others;
(2) Offends decency;
(3) Unlawfully interferes with, obstructs, or tends to obstruct, or renders dangerous for passage, any lake or navigable river, bay, stream, canal, or basin, or any public park, square, street, or highway;
(4) In any way renders other persons insecure in life, or in the use of property.
In SDCL 21-10-3, the Legislature differentiates between public and private nuisances: “A public nuisance is one which affects at the same time an entire community or neighborhood, or any considerable number of persons, although the extent of the annoyance or damage inflicted upon the individuals may be unequal. Every other nuisance is private.” Available remedies against nuisances are: “(1) A civil action; (2) Abatement; and (3) In cases of public nuisance only, the additional remedy of indictment or information as prescribed by statute and rules relating thereto.” SDCL 21-10-5.
*796[¶ 13.] The Restatement Second of ToRts sets forth the common law elements required to establish a private nuisance cause of action, which this Court recognized in Kuper v. Lincoln-Union Electric Company, 1996 SD 145, ¶ 49, 557 N.W.2d 748, 761. See Collins, 2003 SD 100, ¶ 17, 668 N.W.2d at 554; Restatement (Second) of ToRts §§ 822, 824-25 (1979). Under the Restatement, the following conduct gives rise to a claim of nuisance:
One is subject to liability for a private nuisance if, but only if, his conduct is a legal cause of an invasion of another’s interest in the private use and enjoyment of land, and the invasion is either
(a) intentional and unreasonable, or
(b) unintentional and otherwise actionable under the rules controlling liability for negligent or reckléss conduct, or for abnormally dangerous conditions or activities.
Restatement (Second) of ToRts § 822 (1979). “The conduct making an actor liable ‘may consist of (a) an act; or (b) failure to act under circumstances in which the actor is under a duty to take positive action to prevent or abate ... the invasion of the private interest.’ ” Collins, 2003 SD 100, ¶ 17, 668 N.W.2d at 554 (quoting Restatement (Second) of ToRts § 824 (1979)). “An actor’s invasion is considered ‘intentional if the actor (a) acts for the purpose of causing it, or (b) knows that it is resulting or is substantially certain to result from his conduct.’ ” Id. (quoting Restatement (Second) of Torts § 825 (1979)).
[¶ 14.] In his testimony, the owner of Atkinson’s apartment complex, Harvey Buhl, said that Atkinson complained to him once, but that no other tenants complained. He explained that the building in which Atkinson resides has the highest occupancy rate of all Buhl’s residential rental properties, notwithstanding Tour Ice’s location across the street.
[¶ 15.] Kathy Arnold testified that she has lived in the same apartment building on the second floor for seven years. Even when she left her windows open, she said Tour Ice had never inconvenienced her or her family, and the company’s operations were not noticeable. Mayor Dennis Eis-nach of the City of Pierre also testified. He confirmed that no other complaints from any other residents around the ice facility were filed. He recalled that upon learning of the nuisance complaint, he ensured that city officials were in compliance with the ordinances and confirmed that the officials were doing what was required of them.
[¶ 16.] In its findings of fact, the circuit court found “no evidence that indicates that Tour Ice is operating improperly or negligently.” The court also suggested to Atkinson that since she always has her windows open throughout the year, she could decrease her exposure to the noise by closing them. With regard to the degree of noise, the court found that the decibel level was “in the top of the normal range but no where near a danger reading.” 2
[¶ 17.] Although two others from the apartment complex besides Atkinson testified in accord with her position, under *797our standard of review and applying the foregoing legal analysis, we cannot say that the circuit court’s fact findings were clearly erroneous or that its legal conclusions were in error when it concluded that Tour Ice’s operation did not constitute a nuisance. SDCL 9-29-13 provides: “Every municipality shall have power to declare what shall constitute a nuisance and prevent, abate, and remove the same.” Within a city’s express authority is the implied power to declare what shall not constitute a nuisance. We cannot say that the city’s refusal to declare Tour Ice’s operation a nuisance was palpably unreasonable. Moreover, we can find no error in the court’s refusal to declare the business a private nuisance.
B. Interpretation of Zoning Ordinances
[¶ 18.] Atkinson argues that city officials failed to properly interpret the applicable zoning ordinances. Because Tour Ice produces, packages, stores, and delivers ice from its premises, Atkinson contends that its business activities are impermissible in the central business district zoning area. Referring to the 1999 amendments to the city zoning ordinances, she asserts that the central business district only permits assembling and packaging businesses as a conditional use. Tour Ice never obtained a conditional use permit for such use, and therefore she contends it cannot continue to operate.
[¶ 19.] Tour Ice began its operation in 1973. Thus it was subject to the 1970 version of the city’s zoning laws. When it moved to its new location within the same district in 1991, the city interpreted its ordinances to the effect that the company was not required to seek a variance or conditional use permit. The 1999 amendments would not apply to it because under those amendments Tour Ice’s operation constituted a nonconforming use allowed to continue as long as it was in compliance with prior zoning restrictions.3 See Rapp, 2002 SD 146, ¶ 6, 655 N.W.2d at 90 (citing SDCL 11-6-39). Furthermore, the building permits it sought were before the enactment of the 1999 amendments. Accordingly, even if the operation can accurately be described as an assembling and packaging business, the applicable 1970 zoning laws would not preclude it.
[¶ 20.] Atkinson next argues that Tour Ice is a warehouse. Under the 1970 version of the city zoning ordinances, warehouses are prohibited in the central business district. PiERRE City ORD. § 12-6-104 (1970). If it is a warehouse, then it would have required a variance. It never received one. According to the testimony, the company’s process is to produce, package, and store ice until it is ready for delivery. The circuit court found that “Tour Ice sells all the ice it makes each night and stores ice in a real warehouse in Sturgis, South Dakota.”4 From our re-*798view of the record, we think the court’s finding can be supported as not clearly erroneous. City zoning laws do not define the term warehouse, but the ordinary understanding of the term suggests a building or structure designed primarily for storage. That is not the purpose of the building here. It is used to make ice that is stored until shipment, usually the next day.
[¶ 21.] A more difficult question is whether the business can be characterized as manufacturing. Manufacturing businesses are not permitted in the central business district because, under PiERRE City Ord. § 12-6-103 (1970), such district may contain “other light retail and service establishments approved by the Planning Commission, except those uses enumerated in another district.” Manufacturing is a use specifically enumerated in the light industrial district. In defining his business, Ellwein candidly admitted, “we manufacture ice ... that’s a given.”
[¶ 22.] Before moving to its current location, Tour Ice, operating under its former owners, applied for a building permit for 430 South Henry Street. The permit application shows that the proposed use for the building was for “ice manufacturing.” A notation on it states that it was seeking a “special permit for ice manufacture.” According to the city’s building official, Norm Weaver, when the city approved the permit it was only for the building structure which before that time had not met the building codes. But the use of the building for making ice may have required a variance, which the former owners never obtained. Whether a vari-anee is required rests on the meaning of the word “manufacture.”
[¶ 23.] In most instances, we would simply resort to the definition provided in the zoning ordinance, but the 1970 version of Pierre’s ordinance does not define the term.5 A few courts have addressed the question whether the production of ice is manufacturing, usually in the context of taxation. The Louisiana Supreme Court held that the production of ice by artificial means constitutes manufacturing. Ballard v. Kentwood Ice Mfg. & Bottling Works, Ltd., 147 La. 583, 85 So. 598, 599 (1920). In Ballard, the court, without expressing any rationale, held that a business that made and sold ice, meal, ice cream, soda water, and pop, and converted hogs into pork products was a manufacturer. In dicta in People v. Knickerbocker Ice Co., 99 N.Y. 181, 1 N.E. 669 (1885), the court distinguished between the artificial production of ice and the collection and distribution of river ice, explaining, “No doubt ice may be manufactured and frigorifie effects produced by artificial means. Corporations exist for that purpose, and come literally within our manufacturing laws.” Id. at 670. See also Attorney General v. Belle Isle Ice Co., 59 Mich. 157, 26 N.W. 311 (1886) (naturally formed ice collected and reduced by manual labor and machinery to a form adapted for sale and use is “manufactured”).
[¶ 24.] On the other hand, the Pennsylvania Supreme Court held to the contrary. In Commonwealth v. American Ice Co., 406 Pa. 322, 178 A.2d 768 (1962), the court ruled that the artificial production of ice on a commercial basis did not constitute man*799ufacturing. Because there is no lasting change when water is frozen, the court reasoned:
Ice is not a new article. It is still what it was originally — water. In fact, if it is allowed to remain in a warm temperature it reverts to water without any human or mechanical interposition. This cannot be said of any product which is generally accepted to be a manufactured product.... The appellant argues that since, through the process which it applies to water, water acquires a new shape, the resulting product must, therefore, be a manufactured article, but the new shape which we find in a manufactured article must be a permanently new shape.
Id. at 771-72. See also Armour & Co. v. Pittsburgh, 363 Pa. 109, 69 A.2d 405, 409 (1949) (same holding).
[¶ 25.] Given this division of opinion among courts, all we need to ask is whether the city’s interpretation of its own ordinance is unreasonable. As the circuit court wrote, “[a]lthough making ice also could arguably be categorized as ‘manufacturing,’ the city official’s interpretation that making ice is not manufacturing will not be disturbed where the existing use by Tour Ice predates the 1999 ordinance.” The term was not defined in the 1970 version of the ordinance. To now impose a court-made definition would have the effect declaring unlawful an existing thirty-two year business. We would be supplying a meaning to a word in the ordinance that the city has never given to it. “Zoning laws may not operate retroactively to deprive property owners of prior vested rights by preventing a use that was lawful before the enactment of the zoning laws.” Rapp, 2002 SD 146, ¶ 6, 655 N.W.2d at 90.
[¶ 26.] Even if we were to declare today that the making of ice constitutes manufacturing as that term is used in the Pierre zoning ordinances, we would exceed the powers granted under the writ of mandamus to require Tour Ice to cease, or curtail operations. A “writ of mandamus may be issued ... to compel the performance of an act which the law specially enjoins as a duty....” SDCL 21-29-1. “Mandamus is a potent, but precise remedy. Its power lies in its expediency; its precision in its narrow application. It commands the fulfillment of an existing legal duty, but creates no duty itself, and acts upon no doubtful or unsettled right.” Sorrels v. Queen of Peace Hosp., 1998 SD 12, ¶ 6, 575 N.W.2d 240, 242. Mandamus can only issue when the duty to act is unequivocal. Black Hills Cent. R.R. Co., 2003 SD 152, ¶ 13, 674 N.W.2d at 34. With the lack of a definition in the city’s zoning ordinance and the difference of opinion on whether ice making is a manufacturing operation, the city’s duty to act is hardly unequivocal.
[¶27.] We have a business here that has always acted with the. city’s formal blessing. As the circuit court reasoned, “Tour Ice received building permits from the City of Pierre for the construction of additional facilities on the location,” and in doing so, the company was authorized to expand its business. If the city issued those building permits in violation of its public or official duty, mandamus still would not lie to compel the undoing of a completed act. See Crowley v. Spearfish Indep. Sch. Dist., 445 N.W.2d 308, 311 (S.D.1989); Beresford Indep. Sch. Dist. v. Fletcher, 66 S.D. 500, 287 N.W. 497, 498 (1939). We think the circuit court correctly denied relief.
[¶ 28.] Atkinson raises several other issues which either lack sufficient merit for discussion or were not raised at the time of *800trial.6 Thus, we decline to address them. Knudson v. Hess, 1996 SD 137, ¶8, 556 N.W.2d 73, 75.
[¶ 29.] Affirmed.
[¶ 30.] GILBERTSON, Chief Justice, concurs. [¶ 31.] ZINTER, Justice, concurs specially. [¶ 32.] SABERS and MEIERHENRY, Justices, dissent.. The city's ordinance provides:
The following principal uses and structures *794are permitted in the Central Business District: (1) Financial institution[;] (2) Hotel/Motel[;] (3) Municipal or government buildings!;] (4) Office!;] (5) Parking facility or lot[;] (6) Personal and health service store!;] (7) Public transportation facility!;] (8) Public utility facility!;] (9) Railroad thru and spur tracks!;] (10) Retail or service store!;] and (11) Other light retail and service establishments approved by the Planning Commission, except those uses enumerated in another district.
Pierre City Ord. § 12-6-103 (1999). "The following principal uses are hereby declared incompatible with the purpose of the central business district and are hereby expressly excluded. (1) Drive-in theaters!;] (2) Warehouses!;] (3) Petroleum bulk storage!;] (4) Mobile home parks!;] and (5) One and Two-family dwellings.” Pierre City Ord. § 12-6-104 (1999). The following uses are conditional uses and require a permit pursuant to the 1999 amendments to the ordinances: "(1) Assembly and packaging!;] (2) Automotive sales, service, & storage!;] (3) Daycare Facility!;] (4) Gas Dispensing Station!;] (5) Mixed business/residential use[;] (6) Multiple family dwellings!;] (7) Mini-storage facility (4,000 sq. ft. or less).” Pierre City Ord § 12-6-106 (1999).
. To reach their conclusion that this noise constitutes a nuisance, the dissenters invoke certain EPA criteria they apparently downloaded from the Internet, from a website called "Noise Pollution Clearinghouse.” However, these materials state that they do "not constitute a standard, specification, or regulation.” And, in fairness, it must be pointed out that these materials were never presented to the trial court and thus were never considered by the court. To introduce this material now and use it as evidence to reverse the trial court is a violation of SDCL 15-26A-10 ("Supreme Court may review all matters appearing on the record (emphasis added).
. As defined in Pierre City Ord. § 12-1-101(13), an "existing building” is "a building erected prior to the adoption of this chapter or one for which a legal building permit has been issued.” Because the company's building was constructed before the 1999 amendments, Tour Ice has been operating in the central business district as a valid existing building.
. In its memorandum opinion, which was incorporated into its findings of fact and conclusions of law, the circuit court ruled that under Pierre City Ord. § 12-6-104, warehouses are specifically excluded from the central business district. Nonetheless, as the circuit court noted, "at least two warehouses exist in close proximity to Tour Ice” and Atkinson’s apartment building, both of which are within the same zoning district. Kusler's Beer Distributing and Monick Pipe and Supply are considered wholesale businesses, and both operate warehouses. However, we do not know from the record whether these estab*798lishments predated applicable zoning ordinances or received variances.
. The 1999 amended version defines light manufacturing as "those manufacturing processes that are not obnoxious due to dust, odor, noise, vibration, pollution, smoke, heat or glare. These commercial or industrial uses are characterized by generally having all aspects of the process carried on within the building itself.” Pierre City Ord. § 12 — 1— 101(56) (1999).
. Atkinson's brief argues that (1) the city's building inspector, Weaver, was operating under a conflict of interest, which enticed him to make an arbitrary and capricious decision; (2) the City of Pierre inappropriately delegated power to the building inspector; and (3) her due process rights were violated.