*1371Opinion
SCOTT, J.In issue is whether the adoption by the City Council of the City of South San Francisco (City) of an amendment to a development plan formulated pursuant to the Endangered Species Act (16 U.S.C. § 1531 et seq.) (Act) constitutes an administrative act not subject to referendum. The lower court answered in the affirmative and issued a writ of mandate prohibiting a referendum election. We affirm.
I
Standard of Review on Appeal
We follow the usual standard of appellate review. Our review is limited to a determination of whether there was substantial evidence to support the judgment of the trial court issuing the writ of mandate. (Appelgate v. Dumke (1972) 25 Cal.App.3d 304, 314 [101 Cal.Rptr. 645]; Sunseri v. Board of Medical Examiners (1964) 224 Cal.App.2d 309, 313 [36 Cal.Rptr. 553].) The facts are viewed in the light most favorable to the findings of the trial court. (Appelgate, supra, at pp. 307, 315.)
II
Background on Development of San Bruno Mountain
San Bruno Mountain (Mountain) contains approximately 3,600 acres of land. In 1980, respondent Visitación Associates, in response to intense opposition to development, donated and sold approximately 2,000 acres which it owned to San Mateo County and the State of California and agreed to limit development to one-third of the mountain. Shortly thereafter, it was discovered that the Mission Blue butterfly, which had been listed by the United States Fish and Wildlife Service (Service) as an endangered species in 1976, inhabited the Mountain. Further development, therefore, was restricted by the Act. In response, representatives of the City and County of San Mateo (County), the City, the Service, and the Committee to Save San Bruno Mountain, among others (collectively the Committee) initiated a biological study to determine whether development would result in the extermination of the species. The study concluded that because of encroaching brush, the butterflies’ continued existence was threatened even without development. On the basis of the study, the Committee began formulating a plan which would both protect endangered habitat and allow for limited development.
In 1982, Congress, aware of and in recognition of the value of such a plan, *1372amended section 10(a) of the Act (16 U.S.C. § 1539)1 to provide more flexibility in the regulation of development affecting endangered species. The purpose of the amendment was to allow developers to submit to the Secretary of the Interior “conservation plans which provide long-term commitments regarding the conservation of ... species and long-term assurances to the proponent of the conservation plan [i.e., developer] that the terms of the plan will be adhered to and that further mitigation requirements will only be imposed in accordance with the terms of the plan.” (H.R.Conf.Rep. No. 97-835, 97th Cong., 2d Sess., supra, p. 30 (1982).) Congress specifically addressed the issue of amendments to the plan: because “circumstances and information may change over time and ... the original plan might need to be revised... any plan approved for a long-term permit will contain a procedure by which the parties will deal with unforeseen circumstances.” (H.R.Conf.Rep. No. 97-835, 97th Cong., 2d Sess., supra, p. 31 (1982).)
Thereafter, the Committee finalized a habitat conservation plan (HCP) and a contract to implement the HCP (HCP Agreement). The HCP Agreement was signed by the Service, the California Department of Fish and Game, the California Department of Parks and Recreation, the County, the City, Visitación Associates, respondent W. W. Dean & Associates (the holder of an option to purchase a 337-acre parcel from Visitación Associates) (Dean), and others. Following a long period of public review and public hearings, which included the preparation of an environmental impact report (EIR) pursuant to state law, the City approved by resolution in November 1982 the execution of the HCP Agreement. Both appellant and respondents agree that the resolution constituted legislative action. The resolution was not challenged by the referendum process.
The HCP establishes a program for the enhancement of the ecology of all remaining open space on the Mountain. The HCP and HCP Agreement provide for the dedication of approximately 800 acres for open space (in addition to the 2,000 acres previously sold or dedicated), a supervised program of habitat conservation and enhancement, permanent private funding for conservation based upon initial developer contributions and subsequent homeowner assessments, and residential and commercial development within defined boundaries.
The HCP and HCP Agreement set forth a detailed procedure for amendments. Section IX of the HCP Agreement, entitled “Amendments,” subsection B, provides for amendments after (1) a noticed public hearing; (2) *1373written approval of the landowners affected by the amendment, the jurisdiction with local land use authority, the County, and the Service, and (3) a biological study which demonstrates that the amendment will not conflict with the primary purpose of the HCP. Subsection B further provides: “Approval of amendments pursuant to this Section IX{B) is subject to the consent of only those entities mentioned in Section IX(B) and no other entities.”2 (Italics added.) The City then sought a development permit from the Secretary of the Interior based upon the HCP pursuant to section 1539 of the Act. The permit was issued.3
The City subsequently approved, after public hearing, Dean’s specific plan for the development of the south slope area of the Mountain (Terrabay Project), which was consistent with the City’s amended general plan and the HCP. The specific plan provided that the grading proposals should “be considered informational only” and that detailed soil and geotechnical studies would be prepared and their recommendations implemented. Dean then had prepared soils and geotechnical studies which disclosed soil instability in areas designated for preserved habitat which could develop into hazardous landslide problems if Dean’s project went forward. The City therefore required Dean to seek an amendment to the HCP, HCP Agreement, and permit to allow slide repairs in these unstable areas. Without the amendment, the Terrabay Project could not go forward because there was no feasible redesign alternative. The amendment Dean ultimately proposed (in accordance with the findings of a supplemental EIR) provided for the elimination of 24 residential units and additional upslope grading with retaining walls in areas designated for habitat conservation. The amendment requires temporary disturbance of approximately 25 acres designated for conservation, with a minimal short-term impact on the total Mission Blue Mountain population. The amendment also requires Dean to fund offsite habitat enhancement on an additional 30 acres which were not originally scheduled for enhancement under the HCP. The supplemental EIR addressed the amendment’s visual impact: “... these changes are impercep*1374tibie and are insignificant by comparison to the visual impact resulting from the presence of the development itself.”
The City followed the procedure for adoption of amendments under section IX.B. of the HCP Agreement, set forth infra. The City obtained the consent of the City, the County, and the Service; the amendment was supported by a biological study showing it was consistent with the objectives of the HCP; and the City held a public hearing on the proposed amendment. The City approved the amendment by resolution No. 156-85 on July 10, 1985.
Following the City clerk’s certification of the necessary signatures on a referendum petition, the City council voted to set a referendum election on the amendment. In response, respondents filed in the superior court a petition for writ of mandate enjoining the City from holding the referendum election. Following extensive briefing and a hearing on the petition, the court found the amendment constituted merely an implementation of the legislative policies already enunciated after extensive hearings, and therefore was an administrative act not subject to referendum.
III
Governing Statutory and Case Law
Legislative acts of a city which establish general policies and objectives, and the ways and means of accomplishing them, are subject to the referendum process. (Merriman v. Board of Supervisors (1983) 138 Cal.App.3d 889, 891 [188 Cal.Rptr. 343]; Fishman v. City of Palo Alto (1978) 86 Cal.App.3d 506, 509 [150 Cal.Rptr. 326].) Administrative actions, which merely carry out those policies and objectives and are necessary to implement the ways and means already adopted by the Legislature, are not subject to referenda. (Ferrini v. City of San Luis Obispo (1983) 150 Cal.App.3d 239, 249 [197 Cal.Rptr. 694]; Fishman, supra, at p. 509; Lincoln Property Co. No. 41, Inc. v. Law (1975) 45 Cal.App.3d 230 [119 Cal.Rptr. 292].) “This legislative-administrative dichotomy reflects a determination to balance the ideal of direct legislation by the people against the practical necessity of freeing municipal governments from time consuming and costly referenda on merely administrative matters. [Citations.]” (Fishman, supra, at p. 509, fns. omitted.)
Zoning and rezoning ordinances, and the adoption of and amendments to general plans, are legislative actions. (Yost v. Thomas (1984) 36 Cal.3d 561, 570 [205 Cal.Rptr. 801, 685 P.2d 1152]; Arnel Development Co. v. City of Costa Mesa (1980) 28 Cal.3d 511, 516 [169 Cal.Rptr. 904, 620 *1375P.2d 565].) The approval of variances, conditional use permits, and tentative subdivision maps, which involve the application of preestablished standards and conditions to particular land uses, is administrative or “adjudicatory.” (See Horn v. County of Ventura (1979) 24 Cal.3d 605 [156 Cal.Rptr. 718, 596 P.2d 1134]; Arnel Development Co., supra, at p. 518.)
In Valentine v. Town of Ross (1974) 39 Cal.App.3d 954 [114 Cal.Rptr. 678], the Town of Ross adopted schematic plans for a flood control project, reserving rights to approve the detailed plans later. The town council later approved by resolution the detailed plans, and the plaintiff sought a referendum election from the resolution. In holding that the resolution was an administrative act not subject to referendum, the court pointed out that the declaration of public purpose, and the provision of ways and means of its accomplishment, were laid down by the earlier adoption of schematic plans; the later resolution of the town council was an administrative act for their implementation. (Id., at p. 958.)
In Lincoln Property Co. No. 41, Inc. v. Law, supra, 45 Cal.App.3d 230, the city zoned a tract of land “Planned Community.” The city then adopted a development plan in accordance with the zoning which prescribed a number of conditions for the detailed plan to be submitted by the developer. The developer then submitted a detailed plan and tentative subdivision map in accordance with the city’s development plan. Following its approval by the city council, certain members of the community filed a referendum petition. The court found that the city’s development plan constituted a zoning change in which legislative objectives and conditions of development were laid down. The developer’s plan simply carried out those purposes and conditions. The many facets of the detailed plan had been considered at the time of adoption of the development plan. (Id., at pp. 235-236.) The court pointed out that the detailed plan in fact decreased the general size of the buildings approved by the development plan. (Id., at p. 236.) The city’s approval of the plan therefore constituted an administrative act not subject to referendum.
The court in Lincoln Property Co. No. 41, Inc. distinguished the circumstances of its case from those in Millbrae Ass'n for Residential Survival v. City of Millbrae (1968) 262 Cal.App.2d 222 [69 Cal.Rptr. 251], where substantial alterations to a city’s general plan were tantamount to a rezoning of a district and therefore constituted a legislative act subject to referendum. (Id., at p. 236.)
In addition to the above criteria distinguishing administrative from legislative acts, when a city acts to implement a comprehensive system of state regulations affecting a matter of statewide concern, it is acting in an *1376administrative capacity not subject to referendum. (Yost v. Thomas, supra, 36 Cal.3d at p. 570; Associated Home Builders etc., Inc. v. City of Livermore (1976) 18 Cal.3d 582, 596, fn. 14 [135 Cal.Rptr. 41, 557 P.2d 473] [“We distinguish those decisions which bar the use of the initiative and referendum in a situation in which the state’s system of regulation over a matter of statewide concern is so pervasive as to convert the local legislative body into an administrative agent of the state.”].) In Friends of Mount Diablo v. County of Contra Costa (1977) 72 Cal.App.3d 1006 [139 Cal.Rptr. 469], the county board of supervisors approved the rezoning of a vast tract of land, which was not challenged by referendum. The Local Agency Formation Commission (LAFCO) then approved the reorganization of districts within the rezoned area. The court held that the latter action, taken pursuant to the District Reorganization Act (Gov. Code, § 56452 et seq.), was supplemental to the accomplishment of a state purpose and therefore was administrative and not subject to local referendum. (Friends of Mount Diablo, supra, at pp. 1012-1013.)
As a corollary to the above rule, where a local governing body implements federal policy pursuant to a comprehensive plan of federal regulations governing matters of national concern, its actions are administrative and not subject to local referendum. Such result is consistent with the principle of federal preemption: state law is nullified to the extent it stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress. (Fidelity Federal Sav. & Loan Ass'n v. De La Cuesta (1982) 458 U.S. 141, 153 [73 L.Ed.2d 664, 675, 102 S.Ct. 3014]; California Arco Distributors, Inc. v. Atlantic Richfield Co. (1984) 158 Cal.App.3d 349, 357 [204 Cal.Rptr. 743].) We do not hold that federal law entirely preempts all state and local laws when a development is governed by 16 United States Code section 1539. The development permit here in fact requires the observance of applicable local, state, and federal regulations, e.g., the EIR process and public hearing requirements. We do hold, however, that once the interested parties have adopted a conservation plan, and the federal government has issued a development permit conditioned upon strict compliance with the plan, state and local laws do not govern to the extent they conflict with the plan. One federal court has found that when the Act governs land use, regulations which would otherwise govern are nullified to the extent they conflict with the Act. (Pacific Legal Foundation v. Andrus (6th Cir. 1981) 657 F.2d 829, 835.)
In the petition for rehearing, appellant contends that if a state has entered into a cooperative conservation agreement with the Secretary of the Interior under 16 United States Code section 1535, there is no preemption of state law. Section 1535(c) provides that the Secretary of the Interior is “authorized to enter into a cooperative agreement ... with any State which establishes *1377and maintains an adequate and active program for the conservation of endangered species and threatened species.” After the secretary receives a copy of a proposed state program, he may “enter into a cooperative agreement with the State for the purpose of assisting in implementation of the State program.” Appellant contends that because California has a federally approved cooperative conservation agreement, state law governs exclusively here.
Section 1535 is irrelevant to the development in this case. The development here is not part of nor governed by any state cooperative agreement under section 1535(c). The HCP was approved and the development permit was issued pursuant to section 1539(a) of the Act. That section allows the Secretary of the Interior, not the states, to permit limited incidental “takings” of listed endangered species pursuant to a conservation plan approved by the Secretary. Section 1535(c) contains no parallel provision for such an incidental “taking” permit because no such state action is authorized by the Act. Moreover, as appellant itself points out, California’s Endangered Species Act (Fish & G. Code, § 2050 et seq.) does not even protect insect species such as the endangered butterflies on San Bruno Mountain.
IV
Discussion
In the instant case, it is undisputed that the City council’s adoption of the HCP and HCP Agreement were legislative acts. The HCP Agreement and, in more comprehensive form, the HCP, detail the objectives of preservation of an ecological balance and the conservation of “the habitat of nearly 400 native plants [and] animals----” They also set forth the ways and means of accomplishing these objectives. They provide for the dedication of open space, the conservation and enhancement of habitat, permanent private funding for conservation, and limited commercial and residential development within definite boundaries designated on maps incorporated in the HCP.
We find the adoption of the amendment was an administrative act. In so finding, we view the amendment in the context of the many interdependent facets of the HCP as a whole. The amendment is consistent with its objectives and the ways and means of accomplishing them. It does not change the provisions for dedication of substantial open space. It does not alter the boundaries of commercial and residential development, because it requires only grading and retaining walls in unstable areas reserved for conservation. These areas will be revegetated. It does not involve additional residential or commercial construction. In fact, it eliminates 24 residences *1378previously approved and requires additional acreage for habitat enhancement not previously required. Under these circumstances, we cannot say that the amendment calls for a change in land use as proposed under the HCP. Further, the amendment proposes only those changes which are absolutely necessary to enable the Terrabay Project to go forward and implement the HCP Agreement. The record establishes that without the additional grading and retaining walls, the Terrabay Project will not go forward, and funding critical to the implementation of the HCP will be withdrawn.
As in Lincoln Property Co. No. 41, Inc. v. Law, supra, 45 Cal.App.3d 230, changes of the type proposed by the amendment were contemplated at the time of the adoption of the HCP Agreement. Such changes were inevitable where private landowners had agreed to dedicate hundreds of acres of land for open space and to limit the areas of development prior to expending substantial sums for soils studies. For that reason, the HCP Agreement, section IX.R, contains a detailed procedure for the approval of amendments which ensures consistency with the HCP objectives. Section IX.B. sets forth the standards and conditions for amendments, similar to a general plan’s standards and conditions for variances and conditional use permits.
In rebuttal, appellant argues that although Government Code section 65357 anticipates amendments to a general plan and therefore provides the procedure for adoption of amendments, an amendment to a general plan is nevertheless a legislative act. (Yost v. Thomas, supra, 36 Cal.3d at p. 570.) We find a distinction, however, between an amendment to a general plan governed by Government Code section 65357, and the amendment in this case to a conservation plan governed by the Act which is necessary to implement the plan. Government Code section 65357 provides for the adoption of amendments to a general plan by the legislative body by the same procedure required for the adoption of the original plan. With modifications to a conservation plan under the Act, however, Congress foresaw the need for “long term assurances” to be made to the developer for the completion of its project. The Service therefore approved an administrative procedure for necessary amendments consistent with the objectives of the HCP.
Moreover, although generally an amendment to a legislative act is a legislative act (Yost v. Thomas, supra, 36 Cal.3d at p. 570), the purpose and impact of a modification to a land use plan must be analyzed prior to determining whether it is a legislative or administrative act. That the change is termed an “amendment” should not be the dispositive factor. In Fishman v. City of Palo Alto, supra, 86 Cal.App.3d 506, a city council modified a previously approved development plan to permit the construction of a screened enclosure for parked cars. The court held that the modification did not amount to a rezoning and was administrative. The court pointed out that *1379“treating any modification of a [zoned] district as a legislative act is inconsistent with the policy behind the legislative-administrative test, which permits the exercise of some judgment based on the costs and benefits of the referendum procedure.” {Id., at pp. 511-512, latter italics added.) Similarly, here, the HCP Agreement amendment procedure “permits the exercise of some judgment” by the parties required to give their consent— the City, County, and Service—which, under Fishman, is not inconsistent with an administrative act.
We note that the electorate could have rejected by the referendum process the adoption of the HCP Agreement which contained the explicit amendment procedure. The federal government then would have restricted development without the “unique partnership between the public and private sectors in the interest of... conservation” fostered by conservation plans. (H.R.Conf.Rep. No. 97-835, 97th Cong., 2d Sess., supra, p. 31 (1982).) The voters chose not to do so, but instead to accept the benefits of the HCP and HCP Agreement.
Our conclusion that the adoption of the amendment was an administrative act is not inconsistent with Yost v. Thomas, supra, 36 Cal.3d 561, where our Supreme Court confirmed that the adoption of a developer’s specific plan concurrently with approval of an amendment to a general plan were legislative acts. {Id., at p. 570.) Here, the necessary additional grading and retaining walls did not require an amendment to the City’s amended general plan because there is no change in land use such as from single family dwellings to planned community, residential to commercial, or open space to develop-able. The currently unstable upslope area is to remain open space, but stabilized with retaining walls.
That the adoption of the amendment proposed here was an administrative act is also compelled by the fact that the HCP was formulated and the permit was issued to Dean in accordance with federal law affecting a matter of the utmost national concern. (See TVA v. Hill (1978) 437 U.S. 153, 174 [57 L.Ed.2d 117, 134, 98 S.Ct. 2279].) The City, therefore, was acting as an administrative agent of the federal government in implementing the Act which precludes the referendum process. Further, the Secretary of the Interior issued Dean a permit on the basis of the HCP Agreement, which provides at section IX.B. that amendments are subject to the consent of only the entities designated therein. Forcing a developer to submit an amendment to the referendum process after the requirements of section IX.B. have been satisfied conflicts with overriding federal authority. (See also Pacific Legal Foundation v. Andrus, supra, 657 F.2d 829, 835.)
Appellant or other concerned citizens were not without means to challenge the adoption of the amendment. Because the amendment was based upon *1380the findings of a supplemental EIR as well as a determination that it was not inconsistent with the HCP, the City’s administrative action could have been challenged under section 1094.5 of the Code of Civil Procedure as an abuse of discretion. (See, e.g., Bowman v. City of Petaluma (1986) 185 Cal.App.3d 1065, 1071 [230 Cal.Rptr. 413].) That appellant chose not to use this remedy does not confer upon it the right to referendum.
V
Disposition
The judgment issuing the peremptory writ of mandate is affirmed.
Merrill, J., concurred.
Endangered Species Act Amendments of 1982 (Pub.L. No. 97-304 (Oct. 13,1982) 96 Stat. 1422-1424). The House Conference Report states that the San Bruno Mountain Plan is a “model” plan and that “similar conservation plans should be measured against the San Bruno plan ....” (H.R.Conf.Rep. No. 97-835, 97th Cong., 2d Sess., p. 31 (1982).)
Appellant contends that under section IX. A. of the Agreement, the parties were not authorized to effect the amendment pursuant to section IX.B. because the amendment changed the boundaries of the development area. The Service, however, implicitly approved the amendment pursuant to section IX.B. Further, the amendment did not change the boundaries of the development area. The amendment does not entitle Dean to develop but only temporarily to disturb the 25 acres which will be revegetated.
Following the issuance of the permit, a newly formed environmental group challenged the permit in Friends of Endangered Species, Inc. v. Jantzen (N.D.Cal. 1984) 589 F.Supp. 113. Plaintiff contended that the issuance of the permit constituted an abuse of the Service’s discretion and a violation of the National Environmental Policy Act. The Ninth Circuit affirmed the district court’s validation of the permit in every respect, noting Congress’s findings that the San Bruno HCP was a “model” plan. (Friends of Endangered Species, Inc. v. Jantzen (9th Cir. 1985) 760 F.2d 976, 982-983.)