(2) Physical invasion. The Board and applicants contend the neighbors' argument fails under both categories of per se takings: physical invasion and denial of all economically beneficial or productive use of the property. The neighbors do not contend the record supports a finding that the challenged statute denies them all economically beneficial or productive use of their property. Accordingly, we restrict our discussion to the physical invasion category.

According to one commentator,

the term "regulatory taking" refers to situations in which the government exercises its "police powers" to restrict the use of land or other forms of property. This is often accomplished through implementation of land use planning, zoning and building codes. In contrast, a governmental entity exercises its eminent domain power or acts in an "enterprise capacity, where it takes unto itself private resources and uses them for the common good." Where the private landowner will not sell the land, the government entity seeks condemnation of the property and pays a fair purchase price to be determined in court. On the other hand, an inverse condemnation claim is sought by a landowner when the government fails to seek a condemnation action in court.

We think it would aid our analysis of the neighbors' takings argument to discuss those cases where a government entity acting in its enterprise capacity has appropriated private property without first exercising its eminent domain power.

(a) Trespassory invasions of private property by government enterprise. Generally, when the government has physically invaded property in carrying out a public project and has not compensated the landowner, the United States Supreme Court will find that a per se taking has occurred. See Shonkwiler s. 10.01(1), at 369. For example, in Pumpelly v. Green Bay & Mississippi Canal Co., the Court held there was a taking where the defendant's construction of a dam, pursuant to state authority, permanently flooded the plaintiff's property. 80 U.S. 166, 181, 20 L. Ed. 557, 561 (1871). In so holding, the Court enunciated the following rule:

Where real estate is actually invaded by superinduced additions of water, earth, sand, or other material, or by having any artificial structure placed on it, so as to effectually destroy or impair its usefulness, it is a taking, within the meaning of the constitution.

In a more recent case, the Court applied the same rule to a state law that authorized third parties to physically intrude upon private property. Loretto, 458 U.S. at 432 n.9, 102 S. Ct. at 3174 n.9, 73 L. Ed. 2d at 880 n.9 (holding that a New York statute requiring the owners of apartment buildings to permit cable television operators to install transmission facilities on their property was in violation of the Just Compensation Clause).

(b) Nontrespassory invasions of private property by government enterprise. To constitute a per se taking, the government need not physically invade the surface of the land. See Shonkwiler s. 10.02(2), at 370. For example, in United States v. Causby, the Court held that the frequent and regular flights of government planes over the plaintiffs' land had created an easement in the lands for the benefit of the government. 328 U.S. 256, 266-67, 66 S. Ct. 1062, 1068, 90 L. Ed. 1206, 1213 (1946). The plaintiffs owned a small chicken farm near an airport leased by the government for use by army and navy aircraft. The glide path of one of the runways passed right over the plaintiffs' land at a height of only eighty-three feet. As a result of the aircraft's noise, the plaintiffs had to abandon their commercial chicken operation. Id.

The Court held that the flights' interference with the use of the plaintiffs' land constituted a taking of a flight easement that had to be compensated on the basis of diminution in the land's value resulting from the easement. Id. at 261-62, 66 S. Ct. at 1066, 90 L. Ed. at 1210. In the course of its opinion, the Court stated:

The flight of airplanes, which skim the surface but do not touch it, is as much an appropriation of the use of the land as a more conventional entry upon it. . . . The reason is that there [is] an intrusion so immediate and direct as to subtract from the owner's full enjoyment of the property and to limit his exploitation of it. . . . The superadjacent airspace at this low altitude is so close to the land that continuous invasions of it affect the use of the surface of the land itself. We think the landowner, as an incident to his ownership, has a claim to it and invasions of it are in the same category as invasions of the surface. . . . Flights over private land are not a taking, unless they are so low and so frequent as to be a direct and immediate interference with the enjoyment and use of the land. We need not speculate on that phase of the present case. For the findings of the Court of Claims plainly establish that there was a diminution in value of the property and that the frequent, low-level flights were the direct and immediate cause. We agree with the Court of Claims that a servitude has been imposed upon the land.

In Fitzgarrald v. City of Iowa City, 492 N.W.2d 659, 663 (Iowa 1992), we had occasion to consider a physical invasion claim involving overflying aircraft. As in Causby, the plaintiffs in Fitzgarrald claimed the overflying aircraft so adversely affected the use and enjoyment of their property that a taking had resulted. We rejected the claim because the plaintiffs had failed to prove a "measurable decrease in market value" due to the overflying aircraft. Id. at 665. Nevertheless, we cited Causby for the proposition that "in some circumstances, overflying aircraft may amount to a physical invasion." Id. We recognized that when interferences with property from overflying aircraft result in a measurable decrease in property market value, a taking has occurred. Id. at 663. In such cases, we said "the right to recovery is not for the nuisance that must be endured but for the loss of value that has resulted." Id. The loss-in-value measure of damages is what we would ordinarily use in eminent domain cases. Id. As mentioned, Causby used this same measure of damages.

The United States Supreme Court has allowed compensation for other kinds of interferences short of physical taking or touching of land. See William B. Stoebuck, Condemnation by Nuisance: The Airport Cases in Retrospect and Prospect, 71 Dick. L. Rev. 207, 220-21 (1967) [hereinafter Stoebuck]. For example, in United States v. Welch, the plaintiff had a passage easement over a neighbor's property. 217 U.S. 333, 339, 30 S. Ct. 527, 527, 54 L. Ed. 787, 789-90 (1910). The passage was the plaintiff's only access to a county road. The government flooded the neighbor's property thereby cutting off the plaintiff's only access to the road. The Court held the plaintiff was entitled to compensation for the easement. Id. at 339, 30 S. Ct. at 527, 54 L. Ed. at 789-90. Because the benefitted land -- plaintiff's property -- was not physically touched, this case is "a clear example of condemnation without any physical taking." Stoebuck, at 221; see Nollan v. California Coastal Comm'n, 483 U.S. 825, 831, 107 S. Ct. 3141, 3143 97 L. Ed. 2d 677, 687 (1987) (holding that requiring property owner to give easement of access across his property to obtain a building permit was a physical taking of private property that required compensation).

In Pennsylvania Coal Co. v. Mahon, a state statute prohibited coal mining if it were done in a manner to cause subsidence of any dwelling. Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 43 S. Ct. 158, 67 L. Ed. 322 (1922). The plaintiff had a contract to mine coal under a dwelling but the statute prevented the plaintiff from doing so. Id. The Court held the statute was an attempt to condemn property -- the right to mine coal -- without compensation. Id. at 414, 43 S. Ct. at 159-60, 67 L. Ed. at 326. Mahon "is a situation in which, by denying an owner the occupancy and use of his property interest, the government takes the interest without any semblance of physical intrusion." Stoebuck, at 221.

Richards v. Washington Terminal Co. presents a factual scenario closer to the facts in this case. 233 U.S. 546, 34 S. Ct. 654, 58 L. Ed. 1088 (1914). In Richards, the plaintiff owned residential property along the tracks of a railroad that had the power of eminent domain. The property lay near the mouth of a tunnel. The Court recognized that two kinds of the railroad's activities had partially destroyed the plaintiff's interest in the enjoyment of his property. The first kind involved smoke, dust, cinders, and vibrations invading the plaintiff's property at all points at which the property abutted the tracks. The second kind involved gases and smoke emitted from engines in the tunnel that contaminated the air and invaded the plaintiff's property. A fanning system inside the tunnel forced the emission of the gases and smoke from the tunnel. As to the first activity, the Court denied compensation because it was the kind of harm normally incident to railroading operations. Id. at 554-55, 34 S. Ct. at 657-58, 58 L. Ed. at ___. As to the second activity -- gases and smoke from the tunnel -- the Court concluded the plaintiff was entitled to compensation for the "special and peculiar damage" resulting in diminution of the value of the plaintiff's property. Id. at 557, 34 S. Ct. at 658, 58 L. Ed. at ___. Richards is viewed as recognizing the taking of a property interest or right "to be free from special and peculiar' governmental interference with enjoyment." Stoebuck, at 220. The taking involved "no kind of physical taking or touching -- none whatever." Id. Viewed in this light, Richards "entirely does away with the requirement of a physical taking or touching." Id.; see Nichols s. 6.01, at 6-9 n.11 ("It is not necessary, in order to render a statute obnoxious to the restraint of the Constitution, that it must in terms or in effect authorize an actual physical taking of the property or thing itself, so long as it affects its free use and enjoyment. . . .").

(c) Liability of government for a taking by the operation of a nuisance-producing governmental enterprise. With regard to private nuisances,

the power of the legislature to control and regulate nuisances is not without restriction, and it must be exercised within constitutional limitations. The power cannot be exercised arbitrarily, or oppressively, or unreasonably. . . . It has been broadly stated, as an additional limitation to the power of the legislature, that . . . the legislature may not authorize the use of property in such a manner as unreasonably and arbitrarily to infringe on the rights of others, as by the creation of a nuisance. So it has been held that the legislature has no power to authorize the maintenance of a nuisance injurious to private property without due compensation.

Thus, the state cannot regulate property so as to insulate the users from potential private nuisance claims without providing just compensation to persons injured by the nuisance. The Supreme Court firmly established this principle in Richards, holding that "while the legislature may legalize what otherwise would be a public nuisance, it may not confer immunity from action for a private nuisance of such a character as to amount in effect to a taking." Richards, 233 U.S. at 553, 34 S. Ct. at 657, 58 L. Ed. at ___; see also Pennsylvania R.R. v. Angel, 41 N.J. Eq. 316, 7A. 432, 433 (N.J. Eq. 1886) ("An act of the legislature cannot confer upon individuals or private corporations, acting primarily for their own profit, although for public benefit as well, any right to deprive persons of the ordinary enjoyment of their property, except upon condition that just compensation be first made to the owners.").

A number of state courts have decided takings cases on the basis that the government entity operated a nuisance-producing enterprise. See, e.g., Thornburg v. Port of Portland, 233 Ore. 178, 376 P.2d 100, 106 (Or. 1962) ("[A] taking occurs whenever government acts in such a way as substantially to deprive an owner of the useful possession of that which he owns, either by repeated trespasses or by repeated nontrespassory invasions called nuisance.'"). Significantly, a large number of these cases deal with smoke and odors from sewage disposal plants and city dumps. One commentator describes the cases this way:

Typically, a city sewage plant or dump in the vicinity of, but not necessarily directly adjacent to, the plaintiff's land has wafted its noxious smoke, odors, dust, or ashes, usually combinations of these, over the plaintiff's land, with the obvious result of lessening its enjoyment. No physical touching is present, nor do the courts try to equate the municipal acts with touchings. [Several states] have allowed eminent domain compensation in cases of this kind. . . . More significant than a court's language is the result it announces, and in this respect all the decisions stand for the proposition that nuisance-type activities are a taking. . . .

The commentator ascribes a name to the theory of these cases: condemnation by nuisance. Stoebuck, at 226. And the commentator has formulated the theory this way: "governmental activity by an entity having the power of eminent domain, which activity constitutes a nuisance according to the law of torts, is a taking of property for public use, even though such activity may be authorized by legislation." Id. at 208-09; see also City of Georgetown v. Ammerman, 143 Ky. 209, 136 S.W. 202, 202 (Ky. 1911) (holding that odors from city dump adjacent to plaintiff's property created a nuisance that was a taking of the property); Ivester v. City of Winston-Salem, 215 N.C. 1, 1 S.E.2d 88, 88-90 (N.C. 1939) (holding as part of fundamental law of North Carolina that odors from disposal plant next to plaintiff's property constituted a nuisance and were a taking; North Carolina has no constitutional provision for a "taking"); Brewster v. City of Forney, 223 S.W. 175, 178 (Tex. Ct. App. 1920) (holding under Texas Constitution that odors from a nearby sewage disposal plant resulted in a taking of plaintiff's property); Nichols s. 6.07, at 6-112 (stating under broad view of property -- right to use, exclude, and dispose -- there need not be a physical taking of the property or even dispossession; any substantial interference with the elemental rights growing out of property ownership is considered a taking).

One court long ago anticipated the so-called condemnation by nuisance theory this way:

Whether you flood the farmer's fields so that they cannot be cultivated, or pollute the bleacher's stream so that his fabrics are stained, or fill one's dwelling with smells and noise so that it cannot be occupied in comfort, you equally take away the owner's property. In neither instance has the owner any less of material things than he had before, but in each case the utility of his property has been impaired by a direct invasion of the bounds of his private dominion. This is the taking of his property in a constitutional sense.

Our own definition of a taking is in accord with this concept:

[A] "taking" does not necessarily mean the appropriation of the fee. It may be anything which substantially deprives one of the use and enjoyment of his property or a portion thereof.

As mentioned, the Board's approval of the applicants' application for an agricultural area triggered the provisions of section 352.11(1)(a). The approval gave the applicants immunity from nuisance suits. (Significantly, section 352.2(6) allows an agricultural area to include activities such as the creation of noise, odor, dust, or fumes.) This immunity resulted in the Board's taking of easements in the neighbors' properties for the benefit of the applicants. The easements entitle the applicants to do acts on their property, which, were it not for the easement, would constitute a nuisance. This amounts to a taking of private property for public use without the payment of just compensation in violation of the Fifth Amendment to the Federal Constitution. This also amounts to a taking of private property for public use in violation of article I, section 18 of the Iowa Constitution.

In enacting section 352.11(1)(a), the legislature has exceeded its authority. It has exceeded its authority by authorizing the use of property in such a way as to infringe on the rights of others by allowing the creation of a nuisance without the payment of just compensation. The authorization is in violation of the Fifth Amendment to the Federal Constitution and article I, section 18 of the Iowa Constitution.

The district court erred in concluding otherwise.

D. The remedy.

In Agins v. Tiburon, the California Supreme Court held that when legislation results in a taking, the landowner's remedy is to seek a declaratory judgment action that the legislation is invalid because it makes no provision for payment of just compensation. 24 Cal. 3d 266, 598 P.2d 25, 28, 157 Cal. Rptr. 372 (Cal. 1979); see 1 Nichols, Eminent Domain s. 1.42(1), at 1-157 (3d rev. ed. 1997). The court, however, refused for policy reasons to allow the landowner to sue in inverse condemnation for temporary takings damages. Temporary takings damages represent the damages the landowner suffers up to the time the court declares a statute invalid because it violates constitutional provisions for payment of just compensation. This was the holding in Agins under both the federal and state just compensation clauses. Id.; see 26 Am. Jur. 2d Eminent Domain s. 137 (1996) ("The constitutional requirement of just compensation may not be evaded or impaired by any form of legislation, and statutes which conflict with the right to just compensation will generally be declared invalid.").

Later, the United States Supreme Court had occasion to review the California rule in First English Evangelical Lutheran Church of Glendale v. County of Los Angeles, California, 482 U.S. 304, 107 S. Ct. 2378, 96 L. Ed. 2d 250 (1987). The Court held that invalidation of the offending legislation without compensation for the taking is a constitutionally insufficient remedy for a taking under the Federal Just Compensation Clause. In addition to invalidation, the landowner is entitled to takings damages (temporary taking) that occurred before the ultimate invalidation of the challenged legislation. Id. at 319-21, 107 S. Ct. at 2388-89, 96 L. Ed. 2d at 266-68.

Here the neighbors seek no compensation. Rather, they seek only invalidation of that portion of section 352.11(1)(a) that provides immunity against nuisance suits. We therefore need not concern ourselves with damages for any temporary taking. Accordingly, we hold unconstitutional and invalidate that portion of section 352.11(1)(a) that provides for immunity against nuisance suits. We reach this result under the Fifth Amendment to the Federal Constitution and also under article I, section 18 of the Iowa Constitution.

We reverse and remand for an order declaring that portion of Iowa Code section 352.11(1)(a) that provides for immunity against nuisances unconstitutional and without any force or effect.

We reach this holding with a full recognition of the deference we owe to the General Assembly. That branch of government -- with some participation by the executive branch -- holds the responsibility to sort through the practical realities and, through the political process, reach consensus in highly controversial public decisions. Those decisions demand our sincere respect. The rule is therefore that "[a] challenger must show beyond a reasonable doubt that the statute violates the constitution and must negate every reasonable basis that might support the statute." Johnston v. Veterans' Plaza Authority, 535 N.W.2d 131, 132 (Iowa 1995). The rule finding constitutionality in close cases cannot control the present one, however, because, with all respect, this is not a close case. When all the varnish is removed, the challenged statutory scheme amounts to a commandeering of valuable property rights without compensating the owners, and sacrificing those rights for the economic advantage of a few. In short, it appropriates valuable private property interests and awards them to strangers.

The same public that constituted the other branches of state government to make political decisions with an eye on economic consequences expects the court to resolve constitutional challenges on a purely legal basis. We recognize that political and economic fallout from our holding will be substantial. But we are convinced our responsibility is clear because the challenged scheme is plainly -- we think flagrantly -- unconstitutional.

REVERSED AND REMANDED.

All justices concur except Larson and Andreasen, JJ., who take no part.