Ralph Sletten, et al., Respondents, vs. City of Maplewood, Defendant, Ramsey County, et al., Appellants, and Ronald Brzinski, et al., Respondents, vs. City of Maplewood, Defendant, Ramsey County, et al., Appellants, and Essex Insurance Company, Plaintiff, vs. City of Maplewood, et al., Defendants.

may not be cited except as provided by

Minn. Stat § 480 A. 08, subd. 3 (1998).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C7-98-2377

Ralph Sletten, et al.,

Respondents,

vs.

City of Maplewood,

Defendant,

Ramsey County, et al.,

Appellants,

and

Ronald Brzinski, et al.,

Respondents,

vs.

City of Maplewood,

Defendant,

Ramsey County, et al.,

Appellants,

and

Essex Insurance Company,

Plaintiff,

vs.

City of Maplewood, et al.,

Defendants.

 Filed August 10, 1999

 Affirmed

 Lansing, Judge

 Concurring specially, Crippen, Judge

Ramsey County District Court

File No. C6-97-006504, C0-98-001907, C7-98-003542

Robert A. Hill, Gavin Craig, Robert Hill & Associates, Ltd., 431 South Seventh Street, Suite 2450, Minneapolis, MN 55415 (for respondent Sletten)

Timothy Dodd, Davis, Dodd, Levine & Miller, Ltd., 1219 Marquette Avenue, Suite 200, Minneapolis, MN 55403 (for respondent Brzinski)

Susan Gaertner, Ramsey County Attorney, Stephen P. McLaughlin, Thaddeus R. Lightfoot, Assistant Ramsey County Attorneys, 50 West Kellogg Boulevard, Suite 560, St. Paul, MN 55102 (for appellant Ramsey County)

Considered and decided by Crippen, Presiding Judge, Lansing, Judge, and Kalitowski, Judge.

 U N P U B L I S H E D O P I N I O N

 LANSING, Judge

Ramsey County appeals the district court's order denying statutory and unimproved-land immunity for claims stemming from the maintenance of a county composting facility. Because the neighboring residents' claims against the county arise from the county's conduct in its day-to-day operation of the composting facility and because the county improved the land, we affirm.

 FACTS

In 1984 Hubbard Broadcasting (KSTP) gratuitously leased approximately two acres to the City of Maplewood for operation of a leaf composting facility. The city had previously entered into an agreement with Ramsey County, which provided that Ramsey County would prepare the site, install a fence and necessary signs, obtain insurance, and pay part of the cost to monitor the facility. The city and county agreed to be jointly responsible for the piling, turning, and watering of compost materials at the facility. The city and county jointly operated the site through 1990. In 1991, the county assumed sole control of the facility and obtained a conditional use permit from the city to operate the facility.

From at least 1989 onward, neighbors complained to the city and county that compost at the site was producing strong odors. The respondents in this appeal, the Slettens, Behrens, and Brzinskis (neighbors), who live next to or near the site, complained about the odors and then sued, citing common-law and regulatory violations. They allege that they have experienced an "abnormally high incidence[] of nausea, headache, fever, burning and watery eyes, skin rashes, sore throats, and fatigue" while the county operated the site. Neighbors who have been diagnosed with Respiratory Airways Deficiency Syndrome allege that exposure to the odors and hazardous substances at the site caused their illnesses.

The city, county, and KSTP moved for summary judgment, asserting the claims were barred by immunity and partially barred by the statute of limitations. The district court granted the city's motion for summary judgment on time-barred claims arising before 1991 but denied the county's motion for summary judgment based on statutory and unimproved-land immunity. The court also denied the county's motion to grant summary judgment for KSTP based on the government-contractor shared immunity doctrine. Ramsey County appeals the denial of its immunity motion.

 D E C I S I O N

A political subdivision is generally liable for its torts and the torts of its officers and employees acting within the scope of their employment. Minn. Stat. § 466.02 (1996). But if a claim is "based upon the performance or the failure to exercise or perform a discretionary function or duty," the political subdivision is immune. Minn. Stat. §§ 466.03, subd. 6 (1996); see Janklow v. Minnesota Bd. of Exam'rs, 552 N.W.2d 711, 716 (Minn. 1996) (discretionary immunity is referred to as "statutory immunity"). A governmental unit is also immune from claims for losses caused by the condition of its unimproved land. Minn. Stat. § 466.03, subd. 13 (1996).

This court reviews de novo the denial of an immunity-based summary judgment motion. Gleason v. Metropolitan Council Transit Operations, 582 N.W.2d 216, 219 (Minn. 1998). On review, the facts alleged by the nonmoving party are presumed to be true. Burns v. State, 570 N.W.2d 17, 19 (Minn. App. 1997). The party asserting an immunity defense bears the burden of showing that it is entitled to the defense. Rehn v. Fischley, 557 N.W.2d 328, 333 (Minn. 1997).

 I

Statutory immunity protects "planning level" activity, which involves discretion and the balancing of public policy considerations, but does not protect "operational level" activity, which involves the "day-to-day operations of the government." Holmquist v. State, 425 N.W.2d 230, 232 (Minn. 1988) (citations omitted); see Nusbaum v. County of Blue Earth, 422 N.W.2d 713, 722 (Minn. 1988) (statutory immunity protection "does not extend to professional or scientific judgment where such judgment does not involve a balancing of policy objectives"). A county's conduct is protected only when the county produces evidence that the particular conduct that is the subject of the action was of a policy-making nature involving social, political, or economic considerations. Fisher v. County of Rock, No. C6-97-2263, 1999 WL 498098, at *6 (Minn. July 15, 1999).

The record amply supports Ramsey County's claim that its decision to implement a composting program was a policy decision balancing rising disposal costs, a shortage of landfill space, and environmental concerns. See Angell v. Hennepin County Regional Rail Auth., 578 N.W.2d 343, 346-47 (Minn. 1998) (adoption of plan to limit access to property protected by statutory immunity). Similarly, its choice of location for composting sites reflects a balancing of policy considerations. The county sought a convenient site suitable for large-scale composting. Because of the county's population density, a suitable location was difficult to obtain, and the county balanced a number of factors in identifying a site. But the discretionary act of selecting a composting site does not confer immunity on all subsequent composting activities at the site. To determine whether statutory immunity applies, we must focus not on a consolidated character of the entire activity, but on the precise conduct that gives rise to the claims alleged in the complaint. Nusbaum, 422 N.W.2d at 722.

The complaint identifies the specific conduct as (1) maintaining a nuisance as defined by Minn. Stat. § 561.01 (1996) by spreading odors and "airborne fungicidal spores"; (2) trespassing on the respondents' property; (3) negligently operating the facility; (4) negligently failing to warn the respondents of the contamination at the site; and (5) violating the Minnesota Environmental Response and Liability Act. These allegations address the county's conduct in its day-to-day operations of the composting facility, not on the selection of the site. See Marlow v. City of Columbia Heights, 284 N.W.2d 389, 392 (Minn. 1979) (claims alleging "negligence in failing to maintain [a] facility in a safe condition or to warn of hazards" addressed operational level activity).

When a governmental unit "implements established policy it is generally not immune from liability." Angell, 578 N.W.2d at 348 (citing Steinke v. City of Andover, 525 N.W.2d 173, 175 (Minn. 1995); Holmquist, 425 N.W.2d at 233); see also Penland v. Redwood Sanitary Sewer Serv. Dist., 965 P.2d 433, 438 (Or. Ct. App. 1998) ("[T]he district's purported regulatory compliance does not preclude a determination that its operation constitutes a nuisance."). The operation of the compost facility necessarily requires decisions on what quantity of compost to store at the site, whether to keep yard waste at the site or transfer it to another location, and the amount of yard waste to accept. These operational decisions implement the county's planning decisions. Because statutory immunity does not protect operational decisions, the district court did not err in denying the county's motion for summary judgment.

 II

The county makes a subsidiary argument that it is not liable for nuisance claims because the legislature has not waived governmental immunity for that category of claims. The county's argument is without merit. In passing the Municipal Tort Liability Act in 1963, the legislature made governmental units liable for their torts, subject to the exceptions codified in Minn. Stat. § 466.03. 1963 Minn. Laws ch. 798. The tort of nuisance, codified in the state's first laws, Pub. St. 1858, ch. 64, § 15, predates the Municipal Tort Liability Act.

Although the supreme court has required the legislature to waive immunity for statutory causes of action enacted after the Municipal Tort Claims Liability Act, see Janklow, 552 N.W.2d at 718 (holding the "Whistleblower Act operates as an implied waiver" to statutory immunity), it has not applied this requirement to common law torts such as nuisance. Neither the statute nor the attributes of nuisance claims supports the county's argument. See Restatement (Second) of Torts § 895C cmt. e (1979) ("whenever, in the exercise of a governmental function, a municipality can be found to have created or maintained a nuisance, either public or private, there is no immunity"); W. Page Keeton, et al., Prosser and Keeton on the Law of Torts § 131, at 1054 (5th ed. 1984) (origin of exception is that "a nuisance is often equivalent to a taking of land, or at least an easement").

 III

A governmental unit is not liable for torts that occur on unimproved land that it owns. Minn. Stat. § 466.03, subd. 13. The neighbors argue that unimproved-land immunity does not apply because the county does not own the site. But the county need not own the land in fee simple to be an "owner"; a lessee also may be considered an owner. See Judd v. Landin, 211 Minn. 465, 472-73, 1 N.W.2d 861, 865 (1942) (finding a lessee was an owner). As lessees, the city and the county were "owners" within the meaning of Minn. Stat. § 466.03, subd. 13.

The county's status as an owner, however, does not fully resolve the issue; we must also determine whether the land was "unimproved." The statute does not define "unimproved land," and we therefore rely on the common meaning of the term. Minn. Stat. § 645.08(1) (1996). "[U]nimproved," as it relates to land, means "not built on or cultivated." American Heritage Dictionary 1952 (3d ed. 1992). "Unimproved land" is a "statutory term which includes lands, once improved, that have reverted to a state of nature, as well as lands that have never been improved." Black's Law Dictionary 1531 (6th ed. 1990). The facility's gate, driveway, retention ponds, lighting, and compost piles are all improvements over the state of nature. See Angell, 578 N.W.2d at 348 (loading dock structure was an improvement). The county's improvements to the land prevent the county from claiming immunity for the condition of unimproved land owned by a governmental unit.

The county also argued, in its capacity as indemnitor of KSTP, that KSTP is shielded from litigation by the government-contractor shared immunity doctrine. Because neither statutory nor unimproved-land immunity applies to this litigation, the claim of shared immunity necessarily fails. But we note that no facts support a characterization of KSTP as a contractor rather than a lessor. See Restatement (Second) of Property (Landlord and Tenant) § 18.4 (1977) (landlord may be liable for tenant's activities). The district court did not err in denying immunity to KSTP under the government-contractor shared immunity doctrine.

 IV

In response to the county's remaining arguments, we emphasize that our review in this appeal is confined to immunity issues. Carter v. Cole, 539 N.W.2d 241, 241 (Minn. 1995) (dispute over adequacy of claims or evidentiary support for claims non-appealable in context of immunity). Whether the neighbors' allegations against the county are substantiated or refuted by the evidence is a question for the trier of fact, not an appellate court reviewing the narrow issue of immunity. Gleason v. Metropolitan Council Transit Operations, 563 N.W.2d 309, 318 (Minn. App. 1997), aff'd, 582 N.W.2d 216 (Minn. 1998). The issues raised by the county that relate to the merits of the neighbors' claims are beyond the scope of this appeal. Johnson v. Jones, 515 U.S. 304, 318-19, 115 S. Ct. 2151, 2158-59 (1995) (discussing reasons for separating fact-based challenges to claims' merit from challenges to legal determination of immunity). The county may, of course, test the sufficiency of the allegations or the factual support for the allegations by bringing an appropriate motion to dismiss or a motion for summary judgment. Gleason, 563 N.W.2d at 315 n.1 (encouraging motion practice to test sufficiency of claim in order to preserve narrow operation of immunity); see also Bloss v. University of Minnesota, 590 N.W.2d 661, 664-65 (Minn. 1999) (same). It is far preferable to pursue available procedural remedies than to remonstrate over the circumstances that result from ignoring them.

  Affirmed.

 CRIPPEN, Judge (concurring specially)

A number of statutory immunity cases, like the suit we are reviewing, require special scrutiny on unsupported claims that a continuing operation is negligently managed. In this case, the trial court's decision to deny the county's immunity claim rested on allegations that respondents' injuries were the result of "negligent mismanagement." The majority observes that respondents are alleging negligence in the county's "day-to-day operation" of the composting facility.

These summaries of respondents' claims are discerned from complaints that more prominently suggest the county was at fault, not because of mismanagement, but because it chose to continue operating the facility. The county has statutory immunity for the latter course of conduct. The complaints repeatedly say that injuries trace to the county's "maintenance" of the composting facility and of a "continued" or "existing" use or operation. Allegations of mismanagement vaguely speak of conduct that is unlawful, wrongful, or in violation of pollution and environmental codes. Other general allegations state that release of dangerous substances was caused by negligent conduct.

Unless respondents can prove operational mismanagement, the law requires that the county's immunity be declared before they incur unwarranted costs in defending the lawsuit. The immunity from suit is "effectively lost if a case is erroneously permitted to go to trial." Anderson v. City of Hopkins, 393 N.W.2d 363, 364 (Minn. 1986) (citing Mitchell v. Forsyth, 472 U.S. 511, 524-30, 105 S. Ct. 2806, 2815-17 (1985)). Respect for this proposition of law is heavily taxed when claims are premised on a course of conduct undertaken and continued with immunity and not properly shown to result from negligence in mismanagement of the activity. The governmental body's burden to show its immunity does not diminish the claimant's burden to identify and show support for its triable theory.

We must leave to the trial courts a major role in avoiding improper trials on claims like these. This occurs in diligent pre-trial attention--before and after immunity decisions, and contemporaneously with them--to summary judgment motions that address any specific non-immune topics included in a claimant's pleadings. Appellant Ramsey County suggests, in addition, that the appellate courts should scrutinize these claims as part of immunity reviews, requiring at this stage that claimants at least articulate non-immune claims in terms of standards of care and breach of those standards. See Gerber v. Neveaux, 578 N.W.2d 399, 404 (Minn. App. 1998) (demanding that claimants demonstrate non-speculative evidence or a plan to produce it, review denied (Minn. July 16, 1998)).

I concur in the majority decision because of allegations in respondents' complaints that identify, with some specificity, theories of fault regarding day-to-day management of the composting facility, including fault in (a) neglecting notification duties spelled out in Minn. Stat. § 115.061 (1998), (b) negligent inspection and monitoring of the site, (c) negligent failure to identify hazards and notify affected persons, (d) negligent failure to identify and remove hazards, (e) negligent upkeep of the facility, and (f) other allegations of negligent or "illegal" dumping or release of substances.

Allegations like those just reported, especially the negligence claims that are not presently supported by evidence showing breach of an identified standard of care, create a continuing risk that the county will not be given its appropriate pre-trial relief. But absent further directions from the supreme court, additional scrutiny of pleadings like these, without a full trial, remains in the domain of motions on the merits of the stated claims.

As noted before, when non-immune fault is only generally alleged, the trial court has a continuing duty to scrutinize these claims, even after immunity defenses have been stated and denied. The adequacy of some mismanagement claims may not be sufficiently developed to require further trial proceedings. Other such claims, when more specifically identified and supported by the plaintiffs, may be defeated by the government's equally successful showing that policy-making is involved in the conduct. "Sometimes the implementation of a policy itself requires policymaking." Holmquist v. State, 425 N.W.2d 230, 234 (Minn. 1988).