The district court denied the Save The Dunes Council’s motion to intervene in the United States’ condemnation action against the Northern Indiana Public Service Company. 100 F.R.D. 78. We affirm the denial of intervention.
I
The land involved in this case is a 36.96 acre tract bordering the southern edge of Lake Michigan. This area, commonly known as Crescent Dune, is situated between the Indiana Dunes National Lake-shore on the west, and one of Northern Indiana Public Service Company’s (NIP-SCO) generating stations on the east. The condemnation action underlying this case was instituted by the United States under the authority of the Indiana Dunes National Lakeshore Act, 16 U.S.C. § 460u-12, which authorized the Secretary of the Interior to acquire Crescent Dune. Section 460u-12 placed strict time and monetary limitations on the Secretary’s condemnation action. Among the limitations was the requirement that the property, excluding a sea wall, could not be purchased at a cost greater than $800,000, adjusted by the Consumer Price Index and excluding administrative costs. 16 U.S.C. § 460u-12. NIP-SCO has owned the land since 1932, which presently is subject to a mortgage to secure various bond instruments sold by NIP-SCO. In 1976, the value of the land, including the sea wall, was approximately $1,762,000.
The Save The Dunes Council is an Indiana not-for-profit corporation. The Council, a public interest group incorporated in 1952, seeks legal protection for public use of the Indiana Dunes. Since its incorporation the Council has lobbied extensively for national legislation protecting the dunes and expanding the protected areas. The Council lobbied hard for the passage of the 1976 amendments to the Indiana Dunes Act, which authorized acquisition of Crescent Dune, and prepared the base map used to determine the official boundary information for the 1976 amendments.
Although the United States’ condemnation action was filed in August 1978, the Council did riot move to intervene until April 1982.1 The Council also filed a complaint for mandamus in the United States District Court for the District of Columbia and in the Northern District of Indiana against the Secretary of the Interior on October 19, 1983. These mandamus actions are still pending. On September 7, *8581983, the government and NIPSCO submitted to the trial court a stipulation and joint motion to dismiss. Following briefing and a hearing on the Council’s motion to intervene, the district court denied the motion.
II
Four requirements must be met before intervention will be granted as of right. The application must be timely. The intervenor must show an interest relating to the property or transaction which is the subject of the action. The intervenor must show that the disposition may as a practical matter impair or impede the intervenor’s ability to protect that interest. And, the intervenor must show that that interest is not adequately represented by existing parties. Gautreaux v. Pierce, 690 F.2d 616, 635 (7th Cir.1982). The proposed intervenors must satisfy each requirement before a court will grant the motion to intervene. CFTC v. Heritage Capital Advisory Services, Ltd., 736 F.2d 384, 386 (7th Cir.1984).
The district court found that the Council met only the first requirement of timeliness of the motion but failed to meet the other three requirements. The Council bases its challenge to the court’s denial of intervention on the ground that its interest in Crescent Dune is legitimate, tangible and demonstrable, is unprotected by the parties to this action, and will be substantially impaired if the Council is denied intervention.
The district court examined the Council’s alleged interest in the Crescent Dune and determined that “[w]hile the Council has played a laudatory role in the development of the Indiana Dunes National Lake Shore [sic], with respect to this tract of land, [the Council] is essentially a private citizen with no interest in the property sought to be condemned.” Order at 5. Moreover, the district court determined that NIPSCO had the “paramount ... [and] only legal interest” in Crescent Dune. Id.
To obtain intervention as of right under Rule 24(a)(2), a proposed intervenor must show “a direct, significant legally protectable interest in the property or transaction subject to the action” in which intervention is sought. Wade v. Goldschmidt, 673 F.2d 182, 185 (7th Cir.1982) (per curiam) (citing Donaldson v. United States, 400 U.S. 517, 531, 91 S.Ct. 534, 542, 27 L.Ed.2d 580 (1971)). As the Wade court characterized the issue, the critical concern is not the “theoretical interests of proposed intervenors, ... ‘but whether already initiated litigation should be extended to include additional parties.’ ” 673 F.2d at 184.
An eminent domain proceeding such as this action considers only two legal interests. The first interest is that of the sovereign to exercise the power of eminent domain, which is essential to a sovereign government, United States v. Carmack, 329 U.S. 230, 236, 67 S.Ct. 252, 254, 91 L.Ed. 209 (1946), and exercisable only by the legislature or as conferred by congressional enactment. Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 585-86, 72 S.Ct. 863, 865-66, 96 L.Ed. 1153 (1952). The second interest in an ¿minent domain proceeding is one of private ownership — essentially the ownership of the condemned property.
The interest of the sovereign in this case is that expressed in the Indiana Dunes National Lakeshore Act, Pub.L. 89-761, 80 Stat. 1309 (1966) (codified as amended at 16 U.S.C. §§ 460u to 460u-23), to acquire and preserve for public use certain portions of the Indiana Dunes. This interest can be effectuated by the Secretary of the Interior only as authorized by Congress and only to the extent of appropriations from Congress. The Council cannot claim that its right to intervene derives from this sovereign authority to condemn property for public use. No entity, public or private, other than the legislature, can claim the sovereign authority to condemn property — a “direct, significant legally protectable interest” — unless Congress has delegated that authority to the party. Youngstown Sheet & Tube, 343 U.S. at 585, 72 S.Ct. at 865. Congress has not delegated such authority to the Council; the Secre*859tary of the Interior is the only person to whom Congress has delegated the authority to condemn Crescent Dune. 16 U.S.C. §§ 460u & 460u-12. The Council cannot, therefore, claim that its Rule 24(a) interest in the Crescent Dune is the same as that of the Secretary. Nor can the Council claim an ownership interest in the Crescent Dune. NIPSCO has the only claim to ownership of the Crescent Dune. The dune was acquired in fee by NIPSCO, together with other portions of its Michigan City, Indiana, generating station site in 1932.2
The Council argues, however, that on the basis of Sierra Club v. Morton, 405 U.S. 727, 92 S.Ct. 1361, 31 L.Ed.2d 636 (1972), the Council’s “intense concern for the National Lakeshore,” Appellant’s br. at 7, and “its members’ personal aesthetic, conservational and recreational interest in the property,” id. at 8, is a sufficient interest to allow intervention under Rule 24(a). Sierra Club is distinguishable, however, from the present case. Sierra Club arose under Section 10 of the Administrative Procedure Act (APA), 5 U.S.C. § 702, and not under Rule 24(a). There is a qualitative difference between the “interest” which is sufficient for standing to bring an action under the APA and the “direct, significant legally protectable interest” required to intervene in a condemnation action. The “interest” which will satisfy Sierra Club is simply one “arguably within the zone of interest to be protected” by the statute. 405 U.S. at 733, 92 S.Ct. at 1365. The interest of a proposed intervenor, however, must be greater than the interest sufficient to satisfy the standing requirement. As the Supreme Court in Donaldson stated, the interest must be a “significantly protectable interest.” 400 U.S. at 531, 91 S.Ct. at 542. This circuit has also defined the necessary interest as one that is direct, substantial, and legally protectable. Heyman v. Exchange National Bank of Chicago, 615 F.2d 1190, 1193 (7th Cir.1980).
While the Council’s aesthetic and environmental interest in Crescent Dune may indeed be legitimate and demonstrable, we cannot say that it is direct, substantial, or legally protectable. Therefore, the Council’s interest in “guaranteeing the preservation of [Crescent Dune’s] natural beauty,” Appellant’s br. at 8, for public use is not the type of interest which justifies intervention under Rule 24(a). Wade v. Goldschmidt, 673 F.2d 182 (7th Cir.1982), is particularly appropriate in the present context. In Wade, several property owners brought an action against the United States Department of Transportation and the State of Illinois challenging the proposed construction of an expressway and bridge across their property. Several groups sought and were denied the right to intervene in the action. One of the groups denied intervention was an Illinois nonprofit corporation formed specifically to support construction of the proposed bridge and expressway. Although Wade involved an action under the APA in which the government was a defendant, and not a condemnation action in which the government is a plaintiff, the proposed intervenors in this case nonetheless have sought, as in Wade, to assert the position of the government. In Wade, a panel of this court denied intervention because “the governmental bodies charged with compliance [with federal statutes] can be the only defendants.” 673 F.2d at 185. Similarly, where a proposed intervenor in a federal condemnation suit seeks to assert a position on behalf of the government, intervention must also be denied; only the Congress or its delegate can assert the rights of the sovereign.
Similarly, Meridian Homes Corp. v. Nicholas W. Prassas & Co., 683 F.2d 201 (7th Cir.1982), suggests that the Council’s interest is not “direct” in the sense contemplated by Rule 24(a). In Meridian a panel of this court upheld the denial of intervention by individuals who had an interest in *860one joint venturer’s share of a real estate development. The court stressed that Rule 24(a) demanded “rigor in the requirement that the interest be direct and substantial.” 683 F.2d at 204. The court thus held that a party with a legal right, and therefore an “interest,” “only in the profits of the joint venture” is not entitled to intervene in an action where the resolution of the cause of action involved “[h]ow the profits are generated, how the joint venture is managed, or whether the joint venture continues.” Id.
We therefore determine that just as the interest in Meridian Homes was not “direct and substantial,” so the Council’s “aesthetic and environmental interest” in NIPSCO’s property is not “direct and substantial.”
Accordingly, the district court’s denial of the Council’s motion to intervene as of right in the condemnation action below is affirmed.
III
The Council also appeals the district court’s denial of permissive intervention under Rule 24(b). Permissive intervention is wholly discretionary with the district court and will be reversed on appeal only for an abuse of discretion. EEOC v. United Air Lines, Inc., 515 F.2d 946, 949 (7th Cir.1975). The district court denied permissive intervention “in order to avoid the likelihood of undue delay and prejudice to the rights of the original parties” and to avoid prolonging “an already lengthy and tired lawsuit.” Order at 6. We find no abuse of discretion in this determination.
IV
The Council argues that our failure to allow its intervention in this condemnation action “would be to propose that no environmental group may step in to support a mandate of Congress for protection of land under the National Park System should the Department of the Interior choose not to carry out that mandate.” Appellant’s br. at 7. We disagree with that assertion. An action for a writ of mandamus is always available to the Council or any other citizen seeking “to compel an officer or employee of the United States or any agency thereof to perform a duty owed to the plaintiff.” 28 U.S.C. § 1361. The Council obviously recognizes the possible availability of mandamus since it has filed a complaint for mandamus in both the United States District Court for the District of Columbia, Cause No. 83-3091, and in the Northern District of Indiana, Cause No. H84-0214, both filed on October 19, 1983. Although the remedy of mandamus is a drastic one to be invoked only in extraordinary situations, Allied Chemical Corp. v. Daiflon, Inc., 449 U.S. 33, 35, 101 S.Ct. 188, 190, 66 L.Ed.2d 193 (1980), the Council’s allegations against the Secretary of the Interior are the type for which mandamus would provide a remedy, if appropriate. See United States v. Walker, 409 F.2d 477, 481 (9th Cir.1969). We do not intend to suggest by this that the Council will be successful in its mandamus action. That success, of course, will turn on whether the condemnation action was a ministerial duty, plainly defined and peremptory, or a discretionary duty, McClendon v. Blount, 452 F.2d 381, 383 (7th Cir.1971), an issue not presently before us. Our only holding in this decision is that the Council has no right to intervene in the condemnation proceeding and that permissive intervention was properly denied.
For the above stated reasons, the district court is affirmed.
AFFIRMED.