concurring in the remand:
I concur in the remand, but for reasons different than the majority’s.
Congress intended the term “conservation” in § 209 to refer to the conservation of mineral resources, and not to more general environmental protection measures which may restrict production. The history of the 1933 statute shows that the concept of mineral conservation was advanced repeatedly *608by the bill’s sponsors and managers, and was agreed to by opponents.1 The Committee Reports on this and closely related suspension legislation reinforce this understanding.2 This was also Congress’s intention when it amended § 209 in 1946, an intent shown both by the statutory language and by the legislative history.3 Where, as here, Congress incorporates words with a special meaning in the regulated field, and does so to overcome industry objections to the regulatory program, that congressional choice is entitled to special weight. Corning Glass Works v. Brennan, 417 U.S. 188, 201-02, 94 S.Ct. 2223, 2231, 47 L.Ed.2d 1 (1974). The majority reads “conservation” in its modern sense, and inadequately weighs the special meaning of the term “conservation” intended by Congress.
The Interior Department, which had authored and advocated the 1933 and 1946 statutes, interpreted § 209 to apply only to mineral conservation.4 This example of contemporaneous construction by the responsible cabinet officer is strong evidence of the original meaning, especially where Congress reenacts the statute consistently with that construction. E. g., United States v. Sheffield Board of Commissioners, 435 U.S. 110,131, 98 S.Ct. 965, 979, 55 L.Ed. 148 (1978). The Department acted consistently with this interpretation in subsequent administrative adjudication and rulemaking. The decision in Texaco, Inc., 68 I.D. 194 (1961), relies strongly on this mineral conservation rationale.5 Later rulemaking sharply restricted the grant of lease extensions based on drilling permit restrictions imposed for reasons other than mineral conservation.6 That is precisely the sort of *609argument Copper Valley advances here, since it contends that the Department’s imposition of winter-only drilling restrictions in the drilling permit operated automatically to extend the lease by the same amount of time drilling was forbidden. The Department’s adherence to the mineral conservation rationale is entitled to respect.7 E. g., California v. United States, 438 U.S. 645, 675-76 n. 30, 98 S.Ct. 2985, 3001 n. 30, 57 L.Ed.2d 1018 (1978).
I think a remand appropriate however, for the Secretary and his subordinates relied on legally irrelevant grounds to deny the extension.8 The District Court should return the case to the Secretary and require him to decide explicitly whether winter-only drilling restrictions are “suspensions” under § 209, and to state the policy and legal reasons for his choice among plausible interpretations of § 209.
There are sound practical and legal reasons for this approach. We know little more about Alaskan drilling than the fact that it is expensive and difficult. By pronouncing a rule at sharp variance with present practice in Alaska, we may create significant new land title difficulties in areas which have been subject to leasing, make new investment in oil exploration substantially more risky and expensive, and shortchange the United States as lessor, by conferring an unbargained-for windfall on the holders of existing leases. These are cogent reasons for seeking a careful exercise of the Secretary’s expert judgment before deciding the interpretive issue presented here. Udall v. Tallman, 380 U.S. 1, 16-18, 85 S.Ct. 792, 801, 13 L.Ed.2d 616 (1965); McLaren v. Fleischer, 256 U.S. 477, 481, 41 S.Ct. 577, 578, 65 L.Ed. 1052 (1921). By pronouncing a flat rule before the Secretary has acted, we may significantly impede Alaskan oil development vital to meeting the Nation’s current and future energy needs. I doubt Congress intended that result.
. 78 Cong.Rec. 15363-65 (1932) (remarks of Rep. Eaton, Floor Manager); 79 Cong.Rec. 704-05 (same); 79 Cong.Rec. 1881 (1933) (same); 79 Cong.Rec. 3385-86 (same). Opponents agreed. 78 Cong.Rec. 15364 (1932) (remarks of Rep. LaGuardia).
. S.Rep.No.812, 72d Cong., 1st Sess. 3 (1932); H.R.Rep. No. 1737, 72d Cong., 1st Sess. 3 (1932). The same Congress enacted relief legislation allowing the Secretary to extend oil and gas prospecting permits where they had been suspended in the interests of conserving oil. Act of June 30, 1932, ch. 319, 47 Stat. 445^16 (1932). Under the Mineral Leasing Act as it stood then, Copper Valley would have held a permit and not a lease. Consequently, the Department’s construction of this permit extension statute, a construction strongly emphasizing mineral conservation, is especially relevant here. Letter of Interior Secretary Wilbur to House Pub. Lands Comm., reprinted in H.R. Rep. No. 1145, 72d Cong., 1st Sess. 3 (1932), and in S.Rep.No.786, 72d Cong., 1st Sess. 3 (1932).
. Congress continued to use “conservation” to refer to the conservation of mineral resources and their greatest ultimate recovery. The first sentence of § 209, added in 1946, authorizes lease adjustments “for the purpose of encouraging the greatest ultimate recovery.” The last sentence, also added then, applies § 209 to unit development plans, plans authorized “for the purpose of more properly conserving the natural resources of any oil pool, field, or like area.” Act of Aug. 8, 1946, ch. 916, § 5, 60 Stat. 952 (1946). Conservation is used in this sense elsewhere in the amendments: certain restrictions may be waived “whenever . .. the conservation of natural products may require it;” and subsurface storage is authorized “to avoid waste or promote conservation of natural resources.” Id., 60 Stat. 954 (1946).
The Interior Department, which had submitted the language of § 209 enacted by Congress, strongly agreed. See Development of Oil and Gas on the Public Domain, Hearings Before the Sen. Comm, on Pub. Lands, 79th Cong., 2d Sess. 232-33, 239 (Statement of Secretary Krug); Id., at Appendix 18, 23 (Dept, report and substitute bill, including current version of § 209); Development of Oil and Gas on the Public Domain, Hearings Before the House Comm, on Pub. Lands, 79th Cong., 2d Sess. 9 (1946) (Statement of Secretary Krug).
. See notes 2 and 3, supra.
. Texaco was denied a permit because oil drilling would have resulted in the loss of more than a million tons of potash ore. See Texaco, Inc., 68 I.D. 196-97 (1961). The lease was extended (evidently after potash mining) because the permit denial conserved potash ore. Id. at 198-99. Potash is covered by the Mineral Leasing Act. 30 U.S.C. § 181, 281-85 (1976 ed.).
. 30 C.F.R. § 221.21(b) (1979 ed.). The regulation precludes the § 209 automatic extension argument since the Secretary acted pursuant to his extension authority, including § 209, when he proposed and promulgated the regulation. See 31 Fed.Reg. 2614 (1966); 30 C.F.R. § 221 (1979 ed.) (history note). The Secretary failed to rely on that regulation in dealing with this case, however.
. The majority’s reliance on Gulf Oil v. Morton, 493 F.2d 141 (9th Cir. 1974), is misplaced. That decision allowed suspensions under § 5(a)(1) of the Outer Continental Shelf (OCS) Lands Act, 43 U.S.C. § 1334(a)(1) (1976 ed.), to prevent oil well blowouts in the Santa Barbara channel. That interpretation of the OCS Lands Act is neither controlling nor persuasive on the Mineral Leasing Act extension question here. The language of § 5(a)(1) differs greatly from § 209 of the Mineral Leasing Act. Moreover, the court found that the Submerged Lands Act’s broad statutory definition of conservation, 43 U.S.C. § 1301(e) (1976 ed.), was incorporated into the OCS Lands Act. Gulf Oil v. Morton, supra, at 145. That definition includes plant and fish life, as well as mineral conservation. Id. The Mineral Leasing Act incorporates no such definition. Finally, the legislative history shows that Congress intended “conservation” to be interpreted far more broadly in the OCS Lands Act than it was in the Mineral Leasing Act. Suspension of Operations on Oil and Gas Leases, 78 I.D. 256, 258-60 (1971) (Opinion of Interior Dept. Solicitor). Congress used “conservation” differently in § 209.
. The Secretary’s statute of limitations argument assumes that Copper Valley was not entitled to a mandatory extension under § 209, and so assumed his conclusion to the issue in dispute here. The Secretary’s argument concerning his discretion to deny a permit to a dilatory driller ignores the mandatory language of the statute. Moreover, in 1935, when Congress abolished the system of prospecting permits and replaced it with noncompetitive leases, like the one involved here, it made previously discretionary extensions for holders of prospecting permits mandatory for the leaseholders. Mineral Leasing Act Amendments of 1935, § 17, 49 Stat. 677, ch. 599 (1935).