delivered the opinion of the court.
In this zoning case, the trial court declared “unreasonable, arbitrary and capricious” the denial by the Board of Supervisors of Fairfax County of two applications for rezoning filed by the owners of adjoining tracts of land. The Board seeks reversal of the trial court’s declaration.
The land in question consists of two undeveloped tracts totaling approximately 418 acres located in the southern portion of Fairfax County. Existing zoning, RE-1, in effect for a number of years, permits development on the basis of one single-family-dwelling unit per acre.
On July 27, 1970, Thomas R. Williams and James L. Mcllvaine, owners of one of the tracts, filed an application with the Board for rezoning of their land to R-12.5, a classification which permits up to 2.9 dwelling units per acre. On June 14, 1971, Van Metre Associates, Inc., equitable owner of the second tract, filed an application for similar rezoning. The Board refused to hear the rezoning requests and was forced by court order to take action on the applications. On November 20, 1972, the Board denied the Williams-Mcllvaine application, and on December 18, 1972, it denied the Van Metre application.
The owners of the respective tracts of land then proceeded by way of separate petitions for declaratory judgment to have declared void the Board’s denial of the rezoning requests. The two matters were consolidated, and, after a protracted hearing, the trial court, by order entered July 25, 1973, held that the Board’s denial of the rezoning applications was unreasonable, arbitrary, and capricious. In its order, the court directed the Board to reconsider the applications within a reasonable time and to rezone the land to a category permitting development at a density higher than permitted under the existing RE-1 classification. The Board took no action on the court’s directive, but instead prosecuted this appeal.
In the trial court, the inquiry focused upon two issues: (1) whether certain public facilities, namely, highways, schools, and sewage disposal, were available to serve the land in question, and (2) whether the Board’s denial of the rezoning requests was discriminatory. On appeal, the same two issues are paramount.
The Board takes the position that its denial of the rezoning requests was “mandated by state law and deficiencies in public facilities.” The *51state law on planning and zoning, the Board argues, authorizes it to decide “when” public facilities “will be available,” requires it to plan the growth of Fairfax County and to provide public facilities “consonant with the efficient and economical use of public funds” (Code § 15.1-427), and demands that its zoning actions protect against “undue density of population in relation to the community facilities existing or available” (Code § 15.1-489).
Public facilities to serve the land in question are inadequate, the Board asserts, and it has determined by an adopted policy that higher-density development of the area in which the land in question is located “should not occur until public facilities are adequate.” Its adopted policy, part of a comprehensive plan for the area in question, reflects an awareness, the Board says, of the greater need for public facilities in other areas of the county where urban densities already exist, in contrast to the area in question where, although there is pressure for urbanization, there does not yet exist the capacity to support development at higher densities. Its adopted policy, the Board maintains, constitutes a rational plan recognizing the inadequacy of existing facilities, which requires that the area in question develop at one residential unit per acre until “sometime in the future” when provision of additional public facilities “might” warrant “a more intense use of that land.” And, the Board concludes, because its decision to deny the present rezoning requests was consistent with the rational scheme of its adopted policy, the denial was not discriminatory.
We have no quarrel with the Board concerning its contention, set forth in the foregoing statement of its position, that in its zoning actions it must protect against “undue density of population in relation to the community facilities existing or available” and must make provision for public facilities “consonant with the efficient and economical use of public funds.” The Board’s position in this case, however, is at odds, in its essential elements, with the important findings of the trial court. Immediately upon conclusion of the hearing below, the trial judge stated:
“The Court finds as a matter of fact from the evidence that the public facilities to serve this land are either presently available or will be available in the reasonably foreseeable future.
“The property along the entire eastern boundary of the Van Metre land is presently zoned [for higher density development]. Just to the north of this land are commercial sites plus townhouses, not too *52many hundred feet away from that little tip on the Van Metre land. And also, next to that tip is [property zoned for townhouse development].
“Under these circumstances, the Court is of the opinion that to keep this land in one-acre zoning is unreasonable and arbitrary and capricious.”
Thus, the trial court found that (1) public facilities were or soon would be available to serve the land in question, (2) nearby similarly-situated property had already been rezoned for higher-density use, (3) existing zoning of the land in question was unreasonable and therefore invalid, and (4) it was discriminatory and therefore arbitrary and capricious to deny higher-density zoning to the land in question. The crucial question is whether the evidence supports the trial court’s findings.
The evidence shows that the land in question is located in the Middle Run subwatershed of the Pohick Creek watershed, in an area of Fairfax County south of the Capital Beltway and west of Interstate Highway No. 95. The Pohick Creek watershed, containing approximately 20,000 acres, consists of three segments: Main Branch containing approximately 11,000 acres, Middle Run containing approximately 2500 acres, and South Run containing approximately 6500 acres.
Because of urban development spreading southwardly from Washington, D. C., the Board in 1964 adopted a sewerage plan for the Pohick watershed as part of the county’s integrated sewer system. In 1965, issuance of bonds in the sum of $20 million to implement construction of the integrated system was approved by county voters.
The Pohick sewer plan provided for a sewage treatment plant near the mouth of Pohick Creek and a trunkline serving the Main Branch. The plan provided for no sewerage service in the South Run area and contemplated construction with funds from private developers of a trunkline to serve the Middle Run area. In early 1966, the county entered into a written contract with two developer-owners whereby the latter agreed to defray the cost, several hundred thousand dollars, to construct a trunkline to serve all the land in the Middle Run area. Under the agreement, the developers were to be reimbursed by the county from assessments imposed upon other property owners using the line. As a result of the agreement, a 15-inch trunkline was con*53structed to the eastern boundary of the land involved in the present rezoning applications.
On February 14, 1966, the county planning staff submitted to the Board a proposed comprehensive plan for the future development of the Pohick watershed. At the time, much of the land in the watershed was zoned for single-family occupancy on one-acre or larger lots, although substantial areas had recently been rezoned for development on smaller lots. The proposal emphasized that low-density “development does not provide for the efficient and economical provision of public facilities such as streets and highways, effective mass transit facilities, sewer, water, and drainage systems.”
The Board adopted the plan on January 18, 1967. The plan provided for residential development in the Main Branch and Middle Run areas on smaller lots, furnishing a population density of 10 persons per acre. Pursuant to the plan, a number of parcels of land were rezoned for higher-density development, including property contiguous to the eastern boundary of the land involved in the present controversy.
In July, 1968, because the 1967 plan had not been interpreted as intended and a “sprawl development pattern was emerging,” the Board ordered its planning staff to restudy the Pohick watershed. In January, 1969, the staff submitted its report, recommending that the Main Branch area be declared a “development zone,” where development would be encouraged, and that the Middle Run and South Run areas be declared “holding zones,” where development would be postponed.
In discussions on the restudy report, the Board was advised by the county attorney that “the holding zone technique, as propounded, is just not sustainable from a legal standpoint.” Supervisor Bowman, the leading advocate on the Board of a policy of “staging or timing” development, acknowledged that the “holding zone concept,” without further enabling legislation, was “beyond the realm of authority” of the Board. He pointed out, however, that, although the Board had unsuccessfully sought General Assembly authority “relating to the timing of development,”1 there were “other tools available” to ac*54complish the same objective as the “holding zone concept,” namely, “the object of inhibiting, or deferring, or restraining development of certain densities.” Upon motion of Supervisor Bowman, a resolution was adopted which stated, in part:
“It shall be the policy of the Board of Supervisors to avoid the presence of a population of urban density in the Middle Run sub-watershed until such time as public facilities and services commensurate with such density either shall be available or shall be programmed to be available in the reasonably near future.”
On September 10, 1969, the Board adopted the restudy report, with certain modifications, as a comprehensive plan for development of the Pohick watershed. The plan designated the various areas of the watershed as “neighborhoods.” *2 The land in question is located in neighborhoods 12 and 13, in which development is contemplated at a rate of up to two dwelling units per acre under conventional development and up to 2.2 dwelling units per acre under cluster development.
In addition to the previously-quoted Board resolution, the Pohick Plan contained statements of policy for future development of the watershed. In the statements, the South Run area was designated a holding zone. No reference, however, was made to a holding zone with respect to the Middle Run area. Instead, the policy statements concerning Middle Run declared:
“Between now and 1975, land development in the Pohick watershed should be limited to areas in the Main Branch that are north of the Southern Railroad right of way, west of Rolling Road, and in the vicinity of Lorton. Public expenditures for roads and community facilities between now and 1975 should be concentrated in these-areas.
“Between 1975 and 1980, land development in the Pohick watershed should be limited to the Main Branch and Middle Run areas. *55Public expenditures for roads and community facilities should be concentrated in these areas.”
A provision of the plan required annual review by the Board to determine whether public agency capacity had become adequate to permit higher-density development in the Middle Run area. Such annual review, however, was not undertaken by the Board.
At the time the Pohick Restudy Report was adopted in 1969, 850 acres, or 33.5%, of the 2542 acres included in the Middle Run area had already been zoned for higher-density development. Immediately following adoption of the Report, the Board granted' two applications for higher-density zoning involving 121 acres in the Middle Run area and, shortly before commencement of the trial of the present case, the Board granted another application for similar zoning involving 64 acres. Consequently, at the time of trial, 1035 acres, or 41%, of the 2542 acres in Middle Run had been rezoned for higher-density development.
As a result of the Board’s rezoning actions, the land in question bordered, along the entirety of its more than 7,000-foot eastern boundary, property in the Middle Run area zoned for higher-density development, including townhouse construction. Several hundred feet to the north, although located in the Main Branch area, property is zoned for commercial and higher-density residential use.
As has been noted, adequacy of highways to serve the land in question was one of the concerns in the trial court. There was evidence that the present roads are inadequate to support higher-density development of the land in question. There was other evidence, however, that the road system was being improved and was slated for further improvement. And it was shown that improvement of highway facilities followed, rather than preceded, development of an area.
Adequacy of school facilities was also an item of concern in the trial court, although, on appeal, the Board appears to have lost interest in the point, devoting only the following lines to argument in its opening brief:
“Schools are also a valid consideration in a zoning decision. Va. Code Arm. § 15.1-489. Schools in the area were and will continue to be deficient.”
*56The evidence fails to show, however, any serious deficiency in schools to serve the area. Indeed, the evidence shows that the previously-rapid increase in the county school population had “leveled off” and there were schools not filled to capacity so located that, with some busing, they could serve the land in question. Although the county had established a policy of attempting to construct elementary schools within walking distance of homes in a neighborhood, it was shown that the policy was an ideal not followed in practice and that more than half the county’s school population was bused with the use of some 650 vehicles. A school official acknowledged that the increased number of school children resulting from development at higher density of the land in question could be “absorbed,” without “undue burden,” into the present system. And, as with highways, it was shown that provision of schools to serve a particular area followed, rather than preceded, development of the area.
Adequacy of sewerage facilities was the other item of concern in the trial court. Although the sewer trunkline constructed with funds provided by private developers is in place at one of the boundaries of the land in question, treatment facilities are not presently available because the plant serving the Pohick watershed has become overloaded and a moratorium has been imposed upon additional connections. Treatment capacity, however, will be doubled upon completion in early 1976 of construction now in progress and the Pohick watershed then will have sufficient capacity available. At the commencement of the hearing below, the owners of the land in question stipulated that if the trial court ruled in their favor they would not use the ruling to demand development of the land “prior to the sewer being available.”3 So the question of the adequacy of sewerage facilities became, at most, a mere side issue.
With reference to developability of the land in question, there was testimony that because of its topography and location, it was “far superior” to other property in the Middle Run area. While it was conceded that the owners could develop the land under its existing one-acre zoning “and not lose money,” an expert appraiser testified that it would “border on [the] ridiculous” to develop under existing zoning. The witness gave as reasons for his opinion: (1) “the charac*57ter of the community has changed [and] is no longer an RE-1 neighborhood,” (2) the comparatively-higher per-unit cost of development under one-acre zoning “makes [higher-density development] extremely feasible and certainly is reasonable,” (3) as presently zoned, the land has a value of $1,922,500.00, but if zoned for development at 2.2 dwelling units per acre it would have a value of $4,367,368.00, or a difference of approximately $2,445,000.00, and (4) “a tremendous shortage of buildable lots” exists in Fairfax County and a developer would not attempt “to go” with one-acre zoning “as opposed to holding and going” to a yield of 2.2 units per acre.
The availability of building sites and the economics of building in Fairfax County were the subjects of comment by a number of witnesses. The expert appraiser, previously mentioned, stated that the shortage of buildable lots had caused an increase in cost of building sites and this was the reason “building costs have gone up so fantastically.” One of the owners of the land in question testified that he had “looked from border-to-border in the county for buildable property at an economical basis.” A school official opined that because the county had become “a higher-cost place to live,” it is almost prohibitive for “a working family with young children to come in.”
An expert in urban land economics stated that land in the county is so “zoned and structured,” resulting in expensive development on one-acre cr larger sites, that the county “is becoming more and more a place not simply for the affluent but for the fairly rich.” Pointing out that only 3.3% of the undeveloped land in the Pohick watershed was zoned for higher-density residential development, the witness stated that this was an insufficient supply of developable land. When he attempted to describe the “whole pattern of large-lot zoning” as “exclusionary,” the Board’s objection to his use of the word “exclusionary” was sustained. He then said that he could answer “without using that word,” and continued:
“The availability of land in Fairfax County is now such that in the one-acre and up category there is a great deal of land and so the way in which the land is being managed, only those with substantial means can afford to move into the County. People who would, let us say, earn in the $20,000-a-year category, people who would buy houses in the $50,000 category, do not have adequate opportunity, and people under 40 get very thin, and under that you can forget.”
*58As previously noted, the trial court made four important findings: (1) public facilities were or soon would be available to serve the land in question, (2) nearby similarly-situated property had already been rezoned for higher-density use, (3) existing zoning of the land in question was unreasonable and therefore invalid, and (4) it was discriminatory and therefore arbitrary and capricious to deny higher-density zoning to the land in question. We are of opinion that the record supports each and every one of these findings of the trial court.
In reaching this conclusion, we have not overlooked, but have given full credit to, the presumption of validity which accompanies the Board’s denial of the rezoning requests in this case. The denial was legislative action, action which is presumed to be reasonable. Although this presumption of reasonableness is not conclusive, it survives until the one who attacks the legislative action, and upon whom the burden of proof rests, shows clearly that the action is unreasonable. Board of Supervisors of Fairfax County v. Carper, 200 Va. 653, 660, 107 S.E.2d 390, 395 (1959).
We are concerned, then, with the reasonableness of the Board’s action in denying the rezoning requests. This legislative action was reasonable if the matter in issue, viz., the proper zoning classification of the land in question, is fairly debatable. County of Fairfax v. Parker, 186 Va. 675, 680, 44 S.E.2d 9, 12 (1947). The emphasis here is upon the word “fairly.” Given the human tendency to debate any question, an issue may be said to be fairly debatable when the evidence offered in support of the opposing views would lead objective and reasonable persons to reach different conclusions. The evidence to be sufficient for this purpose must meet not only a quantitative but also a qualitative test; it must be evidence which is not only substantial but relevant and material as well.
In determining whether, in a given case, the presumption of reasonableness of zoning actions prevails or is overcome, we have established these maxims:
“Where presumptive reasonableness is challenged by probative evidence of unreasonableness, the challenge must be met by some evidence of reasonableness. If evidence of reasonableness is sufficient to make the question fairly debatable, the ordinance ‘must be sustained.’ If not, the evidence of unreasonableness defeats the presumption of reasonableness and the ordinance cannot be sustained.” *59Board of Supervisors of Fairfax County v. Snell Construction Corp., 214 Va. 655, 659, 202 S.E.2d 889, 893 (1974).
In the present case, the evidence presented by the owners of the land in question showed that the existing zoning was unreasonable and that higher-density zoning was reasonable. The landowners’ evidence showed that their property was suitable for higher-density development; that the character of the neighborhood had changed materially from the time the land was placed in its one-acre category and even from the time the Board affirmed that classification in 1969; that there was a need for housing constructed on sites smaller than permitted under the existing one-acre classification; that public facilities were or soon would be available to serve the land; and that the land bordered or was nearby other similarly-situated property already zoned for higher-density use.
This evidence was sufficient to neutralize the presumption of reasonableness which attached to the Board’s denial of the rezoning requests and to shift to the Board the burden of producing evidence to establish the reasonableness of its zoning action. City of Richmond v. Randall, 215 Va. 506, 511, 211 S.E.2d 56, 60 (1975). In attempting to carry its burden, the Board relied exclusively upon the Middle Run policies of its 1969 Pohick Creek comprehensive plan, policies which were intended to “avoid” higher-density zoning in the Middle Run area until public facilities “shall be available or shall be programmed to be available in the reasonably near future.” The factual underpinning of the Board’s reliance failed, of course, with the trial court’s finding, supported by the evidence, that “public facilities to serve [the land in question] are either presently available or will be available in the reasonably foreseeable future.”
But even more disastrous to the position of the Board is the evidence that, despite its policy of avoiding higher-density development in the Middle Run area, at the very moment of the adoption of the policies there was already rezoned for higher-density development one-third of the land comprising the area which the Board declared should not develop until at least 1975. Immediately following adoption of the policies, the Board rezoned for higher-density development an additional 121 acres in the same area. And, shortly before commencement of trial of the present case, the Board granted the preferred higher-density status to another 64 acres in the Middle Run area.
It is true, as the Board points out, that a comprehensive plan, similar to the Pohick plan embodying the Middle Run policies, is merely *60a guide for development, rather than an instrument of land use control. In this case, however, the Board, relying upon the density provisions, has used its plan as a sword to permit development of some property in the Middle Run area and, relying upon the timing provisions, has used the plan as a shield to justify denial of similar treatment to other property in the same area.
It is also true, as the Board points out, that the fixing of boundary lines of zoning districts is, by nature, more or less arbitrary. In drawing the line between the land in question “and the urban-density zoning to the east and northeast,” the Board says, it was merely exercising its legislative discretion. The drawing of such lines, however, must rest upon some rational basis to withstand a charge of unreasonableness. In this case, the line between the land in question and the adjoining property is not the only important line. Equally important are the lines the Board drew around the entire Middle Run area. In drawing those lines, the Board included similarly-situated but dis-similarly-zoned property, added to the dissimilarity in disregard of its own policies, and has offered nothing, save the Middle Run policies themselves, as a basis for distinction.
The effect of the application of the Board’s Middle Run policies was to discriminate between similarly-situated property. In the present case, the discrimination was specifically and dramatically directed at the land in question. While hearing and granting other rezoning requests in the Middle Run area, the Board refused even to consider the present requests until forced by court action to hear the applications. But more important, the land in question extensively borders or is nearby other property already zoned for higher-density use. No demonstrated real difference distinguishes the various properties and justifies granting preferred status to one property while denying it to another. This is the same type discriminatory practice described as arbitrary and capricious and therefore condemned in Board of Supervisors of Fairfax County v. Allman, 215 Va. 434, 211 S.E.2d 48 (1975).
Another discriminatory effect, although perhaps unintended, of the Board’s zoning policies was to elevate the cost of building sites and housing and thus tend to exclude from portions of Fairfax County those persons who do not have the “substantial means” to “afford to move into the County.” Zoning action with similar exclusionary effect was held inpermissible in Board of Supervisors of Fairfax County v. Carper, supra.
*61Under all the circumstances of this case, the reasonableness of the Board’s action in denying higher-density zoning to the land in question is not fairly debatable. We affirm the trial court’s findings that the existing RE-1 zoning is invalid as applied to the land in question, and that the Board’s denial of the rezoning application was arbitrary and capricious. The case will be remanded to the trial court with instructions to enter another order. The new order will suspend the adjudication of invalidity for a prescribed period of time and direct the Board to consider further legislative action. Since the evidence shows that the alternative uses proposed by the owners4 are reasonable uses, and that either zoning classification R-17 or R-12.5 would permit such uses, the new order will enjoin the Board during the prescribed period from taking any action which would disallow these uses. The new order will further provide that should the Board fail to comply within the prescribed period, the adjudication of invalidity will become operative and the injunction will become permanent, provided that the landowners shall not put their property to any uses other than those shown by the record to be reasonable.
Affirmed and remanded.
This statement concerned efforts during the 1968 and 1969 sessions of the General Assembly to secure the desired legislation. Later, at the 1972 session, Senate Bill No. 95 was offered. The bill was intended to amend Code § 15.1-486 to permit the “timing” by zoning ordinances “of the development of uses otherwise permitted, when public facilities, including utilities, transportation, education, protective and *54recreational facilities, are not deemed by the governing body to be adequate to support development otherwise permitted in the district.” The bill was not enacted into law.
The plan describes a “neighborhood” as follows:
“A neighborhood is devoted primarily to single-family residences and residentially oriented uses—churches, elementary schools, neighborhood parks, and neighborhood shopping centers. A neighborhood normally contains 5,000 people and is bounded by expressways, arterial highways, or other barriers.”
The Board now complains that the trial court, in accepting the stipulation, improperly permitted the “introduction of new factors into a legislative decision at the time of judicial review.” The Board, however, failed to object when the stipulation was offered, and the complaint will not be considered on appeal. Rule 5:7, Rules of Court.
During trial, the landowners expressed a willingness to accept R-17 zoning, an intermediate classification between RE-1 and R-12.5. In its oral opinion, the trial court indicated that its directive to the Board permitted consideration of the R-17 classification. Our remand carries the same indication.