Opinion for the Court filed by Circuit Judge ROGERS.
The principal issue in this appeal is whether Exemption 6 of the Freedom of Information Act (“FOIA”), 5 U.S.C. § 552(b)(6) (2000), applies to site-specific information about the location of an endangered species where disclosure might identify individuals’ private property. The National Association of Home Builders (“NAHB”) appeals the grant of summary judgment to the Secretary of the Interior on NAHB’s request for release of information on the location of nesting sites of the cactus ferruginous pygmy owl in Arizona. The Secretary provided NAHB with numerous documents on the location of the owl, but, invoking several FOIA exemptions, the Secretary redacted the documents to conceal most of the site-specific location that NAHB sought. Assuming that the requested files are “similar files” under Exemption 6, we hold, upon de novo review, that the public interest in disclosure outweighs the privacy interests reflected in the Secretary’s evidence. Accordingly, because Exemptions 3, 4, and 5 do not bar release of the requested documents, we reverse the grant of summary judgment and remand the case with instructions to order the Secretary to release the site-specific information without revealing individual property owners’ names, which NAHB no longer requests.
I.
In 1997 the Secretary of the Interior designated the pygmy owl as an endangered species and two years later exercised authority under the Endangered Species Act to designate critical habitats for the pygmy owl in Arizona. 16 U.S.C. § 1533(a) (2000); Determination of Endangered Status for the Cactus Ferruginous Pygmy-Owl in Arizona, 62 Fed.Reg. 10,730 (Mar. 10, 1997) (to be codified at 50 C.F.R. pt. 17); Designation of Critical Habitat for the Cactus Ferruginous Pygmy-Owl, 64 Fed.Reg. 37,419, 37,423-25 (July 12, 1999) (to be codified as 50 C.F.R. pt. 17) (“1999 Final Rule”). As a result, large tracts of land in southwest Arizona — over731,000 acres — were set aside as critical habitat for the owl, alerting “the public as well as land-managing agencies to the importance of these areas.” 64 Fed.Reg. at 37,419, 37,422. In the Final Rule, the Secretary explained that he “used data on known pygmy-owl locations” — the site-specific information that NAHB now seeks — initially to identify “important areas” for the owl. Id. at 37,423. The Secretary then used biological information to connect these “important areas” to determine the owl’s likely habitats. Id.
In 1998, NAHB filed a FOIA request seeking “previously documented, sitq-spe-cific locations, with appropriate addresses, identified landmarks, parcel or subdivision maps, polygons, or other points of reference sufficient to allow an average person to locate the property where members of the species are known or believed to exist.” The Secretary, acting through the Fish and Wildlife Service (“FWS”), responded to the request by producing hundreds of documents related to the location of pygmy owls. The Secretary redacted these documents, however, to conceal most of the site-specific locations that NAHB sought. Specifically, the Secretary redacted all section information, site directions, site names, and the names and addresses of owners of private lands on which the pygmy owls and their nests have been located.
Dissatisfied with the Secretary’s response, NAHB filed this lawsuit to compel disclosure of the owl-sighting information on the grounds that NAHB was entitled to the data as a matter of law under FOIA. The Secretary defended the withholding of information under four FOIA Exemptions: *31 Exemption 3, for information “specifically exempted from disclosure” by another statute; Exemption 4, for “trade secrets and commercial or financial information obtained from a person and privileged or confidential”; Exemption 5, for “inter-agency or intra-agency memorandums or letters which would not be available by law to a party other than an agency in litigation with the agency”; and Exemption 6, for “personnel and medical files and similar files the disclosure of which would constitute a clearly unwarranted invasion of personal privacy....” 5 U.S.C. § 552(b)(3)-(6). The Secretary presented the affidavit of FWS Director Jamie Rap-paport Clark, which recounted, in pertinent part, experiences in Texas and Arizona, where bird enthusiasts traveled to the location of pygmy owl sightings and adversely affected both the pygmy owls and the private property owners. In Clark’s opinion, such incidents have created in landowners a “well founded” fear that birdwatchers, in the hopes of glimpsing the owl, will unlawfully invade the landowners’ private property.
The district court granted summary judgment for the Secretary, ruling that the Secretary properly redacted the information under Exemption 6, but that Exemptions 3, 4, and 5 did not apply. The court, relying on the observations in Texas and the Arizona incident, concluded that “releasing the pygmy owl data would result in an unwarranted invasion of privacy.” The court recognized that withholding the information would deny the public information that would enable it to locate the pygmy owl’s nesting sites, and that the public would therefore be unable to determine whether the Secretary had properly designated critical habitats for the owl. Still, the district court was satisfied that the Secretary’s disclosure in the 1999 Final Rule of the method by which critical habitats are designated was sufficient to render the decisionmaking process clear, “even though the ultimate decisions remain secret.”
II.
The Endangered Species Act instructs the Secretary to “determine whether any species is an endangered species or a threatened species because of’ a range of enumerated factors, including “the present or threatened destruction, modification, or curtailment of its habitat or range.... ” 16 U.S.C. § 1533(a)(1). Once the Secretary identifies a species as endangered, the Act imposes penalties upon “any person” who engages in certain prohibited actions with respect to the species. Id. § 1538(a). The Act also provides that the Secretary, “to the maximum extent prudent and determinable,” shall “designate any habitat of [an endangered or threatened species] which is then considered to be a critical habitat....” Id. § 1533(a)(3). The Act specifies that the Secretary should base the critical habitat designation on “the best scientific data available” and should consider “the economic impact, and any other relevant impact, of specifying any particular area as a critical habitat.” § 1533(b)(2). In the 1999 Final Rule, the Secretary explained that, in making critical habitat designations, the information about the location of an endangered species is used to form “an interconnected system of suitable and potential habitat areas.... ” 64 Fed.Reg. at 37,423. “[W]ithin the delineated critical habitat boundaries,” the Secretary noted, “only lands containing, or ... likely to develop, those habitat components that are essential for the primary biological needs of the pygmy-owl are considered critical habitat.” Id.
The purpose of the Freedom of Information Act, as the Supreme Court instructed in
Department of the Air Force
*32
v. Rose,
is “ ‘to pierce the veil of administrative secrecy and open agency action to the light of public scrutiny....’”
A.
Under Exemption 6, a federal agency may withhold “personnel and medical files and similar files the disclosure of which would constitute a clearly unwarranted invasion of personal privacy.” 5 U.S.C. § 552(b)(6). Thus, the threshold question is whether the requested information is contained in a personnel, medical, or similar file.
United States Dep’t of State v. Wash. Post Co.,
In considering the scope of the “similar files” language in Exemption 6, the Supreme Court has made clear that information that “applies to a particular individual” may qualify for protection.
Dep’t of State v. Wash. Post,
The files that NAHB seeks are not files that would normally be described as “de-tailed Government records on an individual.”
Dep’t of State v. Wash. Post,
The court need not resolve whether the pygmy owl records constitute “similar files” under Exemption 6. The Supreme Court has embraced the legislative history stating that “ ‘the balancing of private against public interests, not the nature of the files in which the information was contained, should limit the scope of the exemption.’ ”
Dep’t of State v. Wash. Post,
To establish that the release of information contained in government files would result in a clearly unwarranted invasion of privacy, the court first asks whether disclosure “would compromise a substantial, as opposed to a
de minimis,
privacy interest.”
Horner,
The Secretary relies on the declaration of FWS Director Clark to show that disclosure of private landowners’ names and addresses would constitute an unwarranted invasion of those individuals’ privacy because birdwatchers and other persons intensely interested in the location of pygmy owls will unlawfully trespass upon the private lands. Clark described an incident in Arizona in which the Audubon Society placed the location of a pygmy owl sighting on its website and telephone hotline: “On the same day the information was placed on the Audubon hotlines several car loads of birders were observed in the area of the reported location. The following day birding groups included at least two out-of-state vehicles.” Clark noted that “property owners indicated displeasure at the number of people on and around their properties” during the Arizona incident. She added that, in light of these prior experiences, “several landowners have already discussed their fears of disclosure of the information.... ” Clark also referred ambiguously to adverse effects from birders on pygmy owls in Texas, but at oral argument the Secretary disavowed any reliance on incidents in Texas as evidence of trespass by birdwatchers.
NAHB contends that the district court erred in relying on what it characterizes as Director Clark’s speculative and internally inconsistent declaration. Essentially, NAHB maintains that the single Arizona incident cited by Clark is insufficient to support the speculation that birdwatchers would not only seek out this information in order to locate the owls but would then go to the location and unlawfully trespass on private property. Although it is true that Clark noted that landowners “indicated displeasure at the number of people on and around their properties,” it is also true that Clark did not affirmatively state that illegal trespass was a problem during the Arizona incident. And in the 1974 study on which Clark based her conclusion regarding adverse effects on the Texas pygmy owl population, the author stated that the birds were located on “privately owned land,” and thus “harassment may not be a problem.” Further, the Clark affidavit included as an exhibit an advertisement by a private ranch proclaiming the presence of pygmy owls on its property, but the Secretary offered no evidence that this establishment has been overrun by lawless birdwatchers, as feared by the Secretary and the district court.
The Secretary’s evidentiary support for unlawful trespass, therefore, is weak. One incident in which there is no claim that unlawful trespass occurred hardly demonstrates a general problem, and there is nothing to suggest that property owners cannot be protected against unlawful trespassers. Even if property owners have expressed displeasure about birdwatchers’ presence on and around their properties, those statements bear little weight in light of the landowners’ awareness that the owl information could be disclosed. Before allowing the Arizona Game and Fish Department (“State agency”) to survey on their land for pygmy owls, the property owners sign confidentiality agreements providing that although the information will be held confidential, it is subject to public disclosure laws and court orders. As the Secretary rightly notes, this court has stated that where “a substantial probability that disclosure will cause an interference with
*35
personal privacy” exists, “it matters not that there may be two or three links in the causal chain.”
Horner,
NAHB contends, somewhat less persuasively, that “minimal privacy interest” exists in the “unfocused information” that would be disclosed in this case. It suggests that the data is of dubious reliability for the purposes for which the Secretary speculates it will be used, because it is too voluminous and too old, and because it includes both active and inactive sightings. The Secretary’s privacy claim holds some merit, however, because the address of a private landowner on whose property an endangered species has been spotted is not necessarily “unfocused information.” Knowing the square and lot numbers of a parcel of land is only a step from being able to identify from state records the name of the individual property owner. In the context of an individual residence, the court has recognized that “the privacy interest of an individual in avoiding the unlimited disclosure of his or her name and address is significant.... In our society, individuals generally have a large measure of control over the disclosure of their own identities and whereabouts.”
Horner,
Viewing the asserted privacy interests as involving more than minimal invasions of individual privacy, the court must still address the question whether the public interest in disclosure outweighs the individual privacy concerns. As noted, our inquiry is limited to the question whether disclosure will shed light on the “agency’s performance of its statutory duties.”
Bibles v. Or. Natural Desert Ass’n,
NAHB asserts several “public” interests in disclosure. The first fails because the “ ‘purposes for which the request for information is made’ ” have “no bearing on whether information must be disclosed under FOIA.”
Bibles,
But NAHB also points to the public interest in examining the FWS’s use of the owl data in the 1999 critical habitat designation and “on a day-to-day basis ... in a broad array of other contexts.” Appellant’s Br. at 23. This interest in exploring how the Secretary and the FWS are using the information is distinct from NAHB’s more limited interest in itself using the information to advance its lobbying efforts. The former relates to “citizens’ right to be informed about ‘what their government is up to,’ ”
Reporters Comm.,
Upon balancing the privacy interest against the public interest, we conclude that the privacy interest is relatively weak. As the court’s reasoning in
Horner
indicates, disclosure of site specific information is not “inherently and always a significant threat” to privacy.
The other reasons put forth by the Secretary do not lend weight to the asserted privacy interest. The Secretary has established only the speculative potential of a privacy invasion without any degree of likelihood. The access agreement between private landowners and the State agency neither significantly supports the privacy interest asserted nor bars disclosure, as the agreement expressly provides that the information is subject to public disclosure. Given the strong public interest in knowing “what the government is up to,” we hold that the Secretary has failed to rebut the presumption favoring disclosure, which is at its zenith under Exemption 6,
Wash. Post v. HHS,
B.
The Secretary additionally relies on Exemptions 3, 4, and 5 to justify withholding the information NAHB requests. We agree with the district court that these exemptions do not preclude disclosure.
Exemption 3 covers data “specifically exempted from disclosure by statute ... provided that such statute (A) requires that the matters be withheld from the public in such a manner as to leave no discretion on the issue, or (B) establishes particular criteria for withholding or refers to particular types of matters to be withheld.” 5 U.S.C. § 552(b)(3). Consistent with congressional intent that exemptions to disclosure be narrowly construed, the court has identified nondisclosure statutes as those that are “the product of congressional appreciation of the dangers inherent in airing particular data” and that “incorporate! ] a formula whereby the administrator may determine precisely whether the disclosure in any instance would pose the hazard that Congress foresaw.”
Am. Jewish Cong. v. Kreps,
The Secretary’s reliance on the Endangered Species Act as a statute that establishes particular criteria for withholding particular types of matters is misplaced. Looking first to “the plain language of the statute,”
Ass’n of Retired R.R.
Workers,
Inc. v. United States R.R. Ret. Bd.,
Contending that § 1533 supplies criteria for determining whether it would be “prudent”' to include or withhold particular location information in the critical habitat designation, the Secretary also points to legislative history that, in her view, suggests that Congress contemplated permitting the Secretary to withhold information in the critical habitat designation.
*38
The cited committee reports indicate that the Secretary should act in “the best interest of the species” and note approvingly the interpretation of “prudent” to refer to situations “where the designation of critical habitat would inform those who would take a species illegally....” H.R.Rep. No. 95-1625, at 16 (1978),
reprinted in
1978 U.S.C.C.A.N. 9453, 9466; H.R.Rep. No. 97-567, at 20 (1982),
reprinted in
1982 U.S.C.C.A.N. 2807, 2820. However, for purposes of qualifying as a withholding statute under Exemption 3, a statute “must
on its face
exempt matters from disclosure. We must find a congressional purpose for exempt matters from disclosure in the actual words of the statute (or at least in the legislative history of FOIA) — not in the legislative history of the claimed withholding statute, nor in an agency’s interpretation of the statute.”
Reporters Comm. for Freedom of the Press v. United States Dep’t of Justice,
Exemption 4 protects “trade secrets and commercial or financial information obtained from a person and privileged or confidential.” 5 U.S.C. § 552(b)(4). The terms in Exemption 4 are to be given their “ordinary meanings,”
Pub. Citizen Health Research Group v. Food and Drug Admin.,
The Secretary contends that Exemption 4 applies because the withheld information is confidential commercial information. The Secretary points to a cooperative agreement between the FWS and the State agency, which initially collects the site-specific information after obtaining permission from the landowner and promising to hold the information in confidence (subject to certain exceptions). The agreement generally describes the programs and relationships between the parties and also provides that FWS will supply, upon application, “available financial assistance for the implementation of acceptable projects,” and that the parties will “exchange biological and other data....” Because the State agency provides access to its database in return for money, the Secretary maintains that this relationship falls within the ordinary meaning of a commercial transaction.
We are unpersuaded that owl-sighting information qualifies as “commercial or financial” information simply because it was provided pursuant to a government-to-government cooperative agreement. The FWS stated in an internal memorandum (from the Regional Director in Albuquerque, New Mexico) that the State agency is forbidden by statute to sell the owl-sighting data, and it noted that the State agency would be reluctant to do so even if permitted. Instead, the FWS memorandum stated, the State agency provides federal agencies with access to the data only as a condition to the receipt under Section 6 of the Endangered Species Act, 16 U.S.C. § 1535 (2000), of funds that it uses to assist in maintaining its data-colleetion system. Such a quid-pro-quo exchange between governmental entities does not
*39
constitute a commercial transaction in the ordinary sense. No “business information” is involved,
see Wash. Post v. HHS,
Exemption 5 covers “inter-agency or intra-agency memorandums or letters which would not be available by law to. a party other than an agency in litigation with the agency.” 5 U.S.C. § 552(b)(5). Otherwise known as the “deliberative process privilege,” Exemption 5 “shelters documents reflecting advisory opinions, recommendations and deliberations comprising part of a process by which governmental decisions and policies are formulated.”
Petroleum Info.,
The site-specific information that NAHB seeks is predecisional, because the State agency prepared it in part to assist the FWS in making its determinations under the Endangered Species Act. It is not, however, “deliberative.” This court has drawn a distinction between factual information, which “generally must be disclosed,” and “materials embodying officials’ opinions,” which are “ordinarily exempt.”
Id.
Although the “fact/opinion distinction ... is not always dispositive,”
id.,
it is here. The privilege is designed to protect agency policy-oriented judgments and the processes by which policies are formulated, rather than “purely factual, investigative matters.”
Id.
at 1435 (citing
EPA v. Mink,
For these reasons, we hold that Exemptions 3, 4, 5, and 6 do not permit withholding the requested site-specific information. Accordingly, we reverse the grant of summary judgment insofar as the district court ruled that Exemption 6 applied, and we remand the case with instructions to order the Secretary to release the site-specific information while withholding the individual property owners’ names, which NAHB no longer seeks.
