16 U.S.C. 460bb. Although the National Park Service generally requires that pets be on-leash in

national parks, the Park Service allows dog owners to walk their dogs off-leash at Fort Funston.2

         3.         Plaintiff Dog Walkers

         Perhaps because they may run off-leash on voice command, dogs and their owners frequent Fort Funston, although they are not its only visitors. Ft. Funston Dog Walkers was formed in 1996 so that the members could get to know one another and organize regular park clean-ups. The group has approximately 600 members. The group meets once a month on a Saturday morning. Clean-up supplies are provided to members who attend. Annual dues are ten dollars. SFDOG was formed in 1976 as a consolidated voice for dog owners in the San Francisco Bay Area. It has approximately 650 members. Both organizations are plaintiffs. Also serving as plaintiffs are four individuals. Plaintiffs Linda McKay and Lindsay Kefauver are members of Ft. Funston Dog Walkers and frequently walk their dogs in Fort Funston. Ms. McKay is one of the organizers of the Fort Funston Dog Walkers. Plaintiff Florence Sarrett belongs to SFDOG and has frequently visited Fort Funston for more than thirty years. Plaintiff Marion Cardinal is a frequent visitor to Fort Funston.

         4.         The Bank Swallows

         The closure at issue is intended to protect the bank swallow, a species listed as threatened by the California Fish and Game Commission.3  The Fort Funston colony of bank swallows winters in South America and nests in the cliffs at Fort Funston from March or April until August. They burrow small holes horizontally into eroding cliffs, just large enough for a nest. The Fort Funston colony is one of two active colonies remaining on the west coast. Their nesting site used to be at the north end of the Fort Funston cliffs. In 1997 and 1998, however, the colony moved somewhat southward after the El Nino and La Nina winters eroded much of those cliffs. Their new nesting area is still in Fort Funston but is farther south; therein lie the seeds of the controversy.

         5.         The 1995 Closure

         To protect the original nesting area of the bank swallows and for safety reasons, the National Park Service closed two sites in Fort Funston in 1995. One of the two sites covered several acres at the most northern bluffs between the beach and the Coastal Trial. The purpose of this closure was to protect the bank-swallow nesting colonies, located then on the sheer, vertical faces of the bluffs. This closure was unpopular with plaintiffs.

         At the time of the closures, Brian O'Neill, the General Superintendent of the GGNRA, represented to Richard Avanzino, president of the San Francisco Society for the Prevention of Cruelty for Animals, that the northern bank-swallow closure would not be expanded southward:

(A.R. US06438-39, ltr. from Gen. Superintendent O'Neill to R. Avanzino, Mar. 15,1995).4 At a large meeting in 1995, Ranger Jim Milestone represented to approximately 250 members of the plaintiff organizations that there would be no further closures (Undated Declaration of Linda McKay filed Apr. 3, 2000, Par.14)

         6.         The 2000 Closure

         Contrary to its statements that the bank-swallow closure would not be expanded, the National Park Service decided in 1999 to do just that. This decision was provoked by the southward move of the bank-swallow nesting. The new closure, the one now at issue, encompasses another ten acres south of the 1995 bluff closure. Fort Funston, as stated, comprises approximately 222 acres along the Pacific coast. The Coastal Trail runs roughly parallel to the beach on top of the bluffs in the northern part of the park. (See map appended hereto.)5  It is the main artery for hikers, joggers and dog walkers. The northern terminus of the Coastal Trail runs through the 1995 closure and curves westward and downward to the beach. About half of the new closure is "seasonal," meaning it is closed only while the bank swallows are in residence, and about half is permanent, meaning year-round. The new permanent closure borders and extends south of the 1995 permanent closure segment. The seasonal closure borders and extends south of the new permanent closure. The new closures are, as stated, about ten acres.

         The new closures comprise land between the Coastal Trail and the cliffs. This land includes undulating terrain and dunes on which dogs run, children play and adults hike. Children enjoy sliding down a steep dune called Joey's Hill. The high points offer excellent elevated scenic views of the surf. Within the closure is the middle of only three gaps providing access to the beach, the steep cliffs otherwise making the descent hazardous. This middle access is particularly important at high tide when the entire beach is awash, providing an avenue to safety midway between the other two gaps.

         Plaintiffs oppose the new closure for several reasons. First, they see it as a violation of the representation that there would be no further closures. Second, they contend that the area being closed is especially pleasant in the views and activities it sustains. Third, they are concerned because the closure voids the middle of three draws to and from the beach.

         7.         The Decision to Implement the 2000 Closure

         In 1998, the GGNRA started organizing to close off the bluff area south of the 1995 permanent closure. On February 2, 1999, the National Park Service generated a project statement. It recommended activities such as nest monitoring and educating the visiting public about the bank swallows and their nests (A.R. US00262-66). Importantly, the project statement also recommended restrictions on park use, including erecting a fence to protect the swallows:

         The National Park Service did not immediately inform the public of its progressing plan. On July 31, 1999, Ranger Mary A. Petrilli, an interpretive ranger at Fort Funston, sent an email to Ranger Chris Powell, a National Park Service public relations staff member, stating that the Bank Swallow Site Extension had been approved through Project Review and that funding had been secured for the new fence line. The email was copied to six other National Park Service staff members. It warned all recipients to be "discreet" with the information in the email and cautioned that "we do not want this to blow up in our faces":

(A.R. US06293, email from M. Petrilli to C. Powell, July 31, 1999) (emphasis added). In September 1999, the National Park Service was hoping to put up the fences in October before the rainy season (A.R. US06225, email from S. Farrell to T. Fortmann, et al., Sept. 1, 1999).

         On October 27, 1999, Ranger Farrell wrote the following email to Ron Schlorff of the California Department of Fish and Game soliciting official DFG input that recreation at Fort Funston should be curtailed to protect the bank swallows:

(A.R. US06939, email from S. Farrell to R. Schlorff, Oct. 27, 1999). A few days later, on November 1, 1999, the park staff briefed the San Francisco Committee of the GGNRA Commission about the need to protect the bank-swallow habitat through closure of a portion of the bluffs (A.R. US04641-44).

         8.         Reaction of the Dog Walkers

         Although the National Park Service had obtained funding for the closure in the summer of 1999 and had originally intended to go forward with the project in the fall of 1999, it was not until December 3, 1999, that the National Park Service informed the Ft. Funston Dog Walkers of their plan, albeit in an indirect way. The topic came up during a so-called walk-through. Walk­through is the term used by the dog walkers and the National Park Service to refer to on-site discussions about park issues. The dog-owner representatives did not know that the walk­through would include a discussion of closures. Instead, they expected to discuss the usual issues such as a dog water fountain on the Coastal Trail, boxes for plastic bags to pick up after dogs, and the locations of several trash cans. During the walk-through, Ranger Chris Powell volunteered that there was a possibility that a further closure south of the 1995 closure might be made for bank-swallow protection and revegetation (A.R. US06200).

         On December 21, 1999, Ranger Roger Scott, a public relations staff member, emailed Ms. McKay a set of minutes purportedly summarizing the walk-through. As stated, Ms. McKay is an organizer of the Ft. Funston Dog Walkers. The minutes stated that "Chris Powell began discussion with the group the very likely possibility that a six-acre cliff area might be restricted from access because of a Bank Swallow relocation and ongoing revegetation project" (A.R. US06200). This statement was more definite than had been the casual and hypothetical conversation during the walk-through. Ms. McKay was surprised by the minutes. She had not understood that the National Park Service was planning to close six acres of property between the beach and the Coastal Trail. She so informed Ranger Kevin Turner, the head ranger and an interpretive specialist, who then sent the following email to a fellow ranger:

(A.R. US06197, email from R. Weideman to M. Scott, C. Powell, R. Scott, and Y. Ruan, Dec. 28, 1999, forwarding email from K. Turner to R. Weideman, Dec. 27, 1999). The day after her meeting with Ranger Turner, Ms. McKay wrote the following email to Rangers Fortmann and Scott regarding problems with the minutes from the December 3 walk-through:

(A.R. US06197, email from L. McKay to T. Fortmann and R. Scoff, Dec. 27,1999) (emphasis added). Later, the actual size of the closure proved to be almost ten acres, not five or six acres as the minutes suggested.

         The walk-through minutes mentioned that closure was to be on the agenda at the January Advisory Committee meeting; however, the dog walkers contend that they did not get notice of the meeting until January 14, 2000, four days before the meeting (A.R. US060200, Dec. 3 Committee Meeting Minutes). When the dog walkers did get a copy of the agenda, the closure was not listed as a public-discussion item. On January 15, 2000, Ms. McKay sent an email entitled "Fort Funston Crisis" to members of Ft. Funston Dogwalkers, informing them of the meeting and the bank-swallow closure issue. The email called on members to attend the meeting: "We need bodies there, even though we may not be able to comment -- but have comments ready if we can!" (email from L. McKay to Ft. Funston Dog Walkers, Jan. 15, 2000).

         The Advisory Committee Meeting occurred on January 18, 2000 (A.R. US06150). Ranger Farrell, a National Park Service plant biologist, and Ranger Hatch, a National Park Service wildlife specialist, gave a slide presentation to illustrate the four objectives of the project: to protect the threatened bank-swallow colony at Fort Funston; to stabilize eroding inland dunes and increase biological diversity by restoring the coastal dune habitat; to increase public safety by reducing visitor exposure to imminent threats; and to protect geologic and historic coastal features from human-induced erosion (A.R. US06151). The meeting was open to the public. Dog walkers, as well as other members of the public, attended and were allowed to speak. Of the thirteen members of the public who spoke, seven were dog owners (ibid.).

         During this period, as before, officials were very aware of the possibility that the dog walkers would wish to be heard and sought to preclude or minimize such input. In this vein, Assistant Superintendent Mary Gibson Scott wrote the following in an email on January 24 with the subject line "Ft. Funston dogwalkers and attachment":

As I have indicated on my messages we have completed the public process for the project (perhaps one of the more contentious ones) and are ready to start. The project involves the installation of approximately 1,750 linear feet of fencing using the same template/construction design as was used at Crissy Field to protect the dunes. The materials are peeler posts, wire mesh, cable and cable clamps and u-nails to attach the mesh to the fence posts.

The project is to protect the state threatened bank swallow species and involves closing 5.8 acres of Fort Funston (much to some of the dog walkers dismay - however will have significant benefit to the swallow). The fence is installed along the coastal trail and is in sand - just like Crissy. There are two areas where the construction will require some thought as the terrain is pretty rough.

The project is probably in the top 10% of the park's most visible projects therefore I have hired a staffperson to work with the public/crew the duration of the project - similar to how we did the tree removal project at Inspiration Point. Brian wants to ensure that we are in and out as quickly and professionally as possible, so if we can have an experienced crew it will probably save us both headaches in the long run. The crew will need to work continuously and consistently for the duration of the project.

James felt that the project was reasonable in the timeframe given so I want to confirm with you that this is feasible - we have had some challenges in the past with underestimation of resources and I want to ensure that it is not the case in the project. What I would like to propose is that if the crew finishes earlier than the contract calls for then we pay you the balance in full - the project is that political. However, on the flip side, after your review we will need the guarantee that the project can be accomplished in the time that we agree upon, and with the resources provided.

A.R. US04208-09, email from S. Farrell to J. Gomes, Jan. 26, 2000, copied to M. Petrilli) (emphasis added)

         9.         The Demand For Public Input and Rebuff

         By early February, the dog owners requested a written record of the public involvement in the National Park Service's decision to close more of the coastal bluffs. These requests triggered a search within the National Park Service for documentation of any public hearings, as reflected by the following series of emails between Michael Feinstein, Ranger Farrell, and Ranger Fortmann:

(Ibid., email from T. Fortmann to R. Scott, Feb. 14, 2000). Ranger Roger Scott then wrote an email to Assistant Superintendent Mary Gibson Scott, Ranger Fortmann, and Michael Feinstein, concluding that there had been no formal notice or hearing before the 1995 closure. Ranger Roger Scott recommended that the National Park Service take the position that no notice or hearing had been necessary as follows:

(A.R. US06260, email from R. Scott to M. Scott, T. Fortmann, and M. Feinstein, Feb. 15, 2000) (emphasis added). According to Ranger Roger Scott's email, outreach staff would be on hand one week prior to commencement of the fences and all through the fence building. The outreach was not for the purpose of receiving input on the closure itself. That was a fait accompli. The outreach was a public-relations campaign to sell the closure and to create the appearance that the National Park Service wanted the public's input. General Superintendent Brian O'Neill and Assistant Superintendent Mary Gibson Scott met with representatives of the dog-walking community on February 17, 2000, to discuss their concerns. Fencing began a few days later, as planned, on February 22, 2000.

         On February 25, 2000, Lydia Boesch, counsel for plaintiffs, faxed a letter to Ranger Fortmann stating that the recreational users of Fort Funston were considering applying for a temporary restraining order to prevent the closure. The letter requested the results of all public use surveys completed in the preceding three years at Fort Funston. Ranger Roger Scott is quoted in a March 1, 2000, newspaper article as saying "[w]e knew this was not going to be a popular thing" (A.R. US06113, Marianne Constantinou, "Dog Owners Snarl At Fences," S.F. Exam., Mar. 1, 2000 at A-1, A-8). Ranger Roger Scott admitted in his deposition that he made this statement.

         10.         Procedural History          

The fences were built between February 22 and mid-March, 2000. On March 13, 2000, plaintiffs simultaneously filed a complaint for injunctive relief and applied for a temporary restraining order preventing the National Park Service from closing off the designated permanent and seasonal closure areas. On March 14, 2000, the Court held a hearing on the motion for a temporary restraining order. The Court granted plaintiffs' application in limited part, allowing the permanent closure to remain closed, but enjoining the National Park Service from closing the seasonal area barring an emergency under 36 C.F.R. 1.5(b). On April 11, the Court visited Fort Funston, accompanied by the parties and their counsel. On April 12, the National Park Service reported to the Court that the bank swallows had returned. The National Park Service declared an emergency and closed off the seasonal area. On April 14, the Court held a hearing on plaintiffs' motion for a preliminary injunction, which this order now addresses.

ANALYSIS

To obtain a preliminary injunction, the moving party must show either (1) a combination of probable success on the merits and the possibility of irreparable injury, or (2) that serious questions are raised and the balance of hardships tips sharply in its favor." Rucker v. Davis, 203 F.3d 627, 634 (91h Cir. 2000) (internal citation and quotation marks omitted). "These are not two tests, but rather the opposite ends of a single continuum in which the required showing of harm varies inversely with the required showing of meritoriousness." Republic of the Philippines V. Marcos, 862 F.2d 1355, 1362 (9th Cir. 1988) (internal citation and quotation marks omitted).

         A strong showing of entitlement to a preliminary injunction is required where the moving party seeks to enjoin governmental action taken in the public interest pursuant to a statutory or regulatory scheme. In such cases, the moving party must establish both irreparable injury and a probability of success on the merits. NAACP, Inc. v. Town of East Haven, 70 F.3d 219, 223 (2d Cir. 1995). But the lower preliminary injunction standard may be applied where there are public interest concerns on both sides. Time Warner Cable of New York City v. Bloomberg L.P., 118 F.3d 917, 923 (2d Cir. 1997). As seen below, the outcome is the same under either the higher or lower standard in this case.

         1.         Likelihood of Success on the Merits and/or Serious Questions

36 C.F.R. 1.5(b). The National Park Service did not publish the 2000 Fort Funston closure as rulemaking in the Federal Register. Thus, if the closure was either "highly controversial" or involved a "significant alteration," the regulation was violated.

        The government argues that the National Park Service made an implicit decision, as evidenced by the lack of a published proposed rule, that the closure was neither of a "highly controversial nature" nor a "significant alteration in the public use pattern." That implicit decision, the government argues, is entitled to deference. According to the government, plaintiffs can prevail only if this implicit decision was arbitrary and capricious based on the administrative record. The Court disagrees.

         While an agency's interpretation of its own regulation is normally given substantial deference by courts, post-hoc rationalizations are entitled to little or no deference, Motor Vehicle Mfrs. Assn. of United States, Inc. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 50 (1983) ("It is well-established that an agency's action must be upheld, if at all, on the basis articulated by the agency itself "). In this case, there was no contemporaneous interpretation whether the closure was "highly controversial" or a "substantial alteration of the public use pattern" before the National Park Service made its decision to put up the fences. Before the fencing began and before plaintiffs sent a letter about seeking an injunction, the National Park Service did not prepare a written determination explaining that the closure was neither "highly controversial" nor a "significant alteration in the public use pattern."

         In addition, the administrative record is replete with evidence that the National Park Service was aware the closure would be highly controversial. As far back as 1995, the National Park Service knew that such closures were strongly opposed by the dog walkers. In 1999, Mary Petrilli cautioned fellow rangers "we do not want this to blow up in our faces" and "[e]veryone copied on this should be very discreet with this information, PLEASE" (A.R. US06293, email from M. Petrilli to C. Powell, July 31, 1999). Assistant Superintendent Mary Gibson Scott indicated that any meetings with the dog walkers should be kept small, so as not to facilitate their further organization by providing them a forum (A.R. US06268, email from M. Scott to D. Mannel, J. Scheumann, Y. Ruan, and T. Thomas and copied to R. Scott, T. Fortmann, M. Bartling, dated Jan. 24, 2000). In organizing the fence-building, Ranger Farrell referred to the closure as "perhaps one of the more contentious" projects, predicted that the closure would be "much to some of the dog walkers dismay," characterized the closure as being "in the top 10% of the park's most visible projects," and proposed to pay the balance in full if the crew finished earlier than the contract called for because "the project is that political" (A.R. US04208-09, email from S. Farrell to J. Gomes, Jan. 26, 2000, copied to M. Petrilli). After the fences started to go up, Roger Scott admitted to a reporter "[w]e knew this was not going to be a popular thing" (A.R. US06113, Marianne Constantinou, "Dog Owners Snarl At Fences," S.F. Exam., Mar. 1, 2000 at A-1, A-8) (quoting Roger Scott). Ranger Scott admitted under oath that he made this statement. The National Park Service did not solicit the views of the dog walkers during the decision-making process. Instead, the National Park Service solicited the views of only select groups in favor of the closure, like the California Department of Fish and Wildlife.

         Now, after the fact, after litigation has commenced, Assistant Superintendent Mary Gibson Scott has submitted a declaration stating that she determined at the time of the justification memorandum that the closure would be neither highly controversial nor a significant alteration in the public use of the land. This declaration is, of course, outside the administrative record. Regardless, the declaration is of limited value. First, it is not contemporaneous, and likely not as reliable as a document drafted at the time the decision was made. Second, even at the time Assistant Superintendent Scott made the Section 1.5(b) decisions regarding "highly controversial" and "significant alteration," plaintiffs had already. threatened litigation, so the undocumented analysis was made in contemplation of litigation. Third, Assistant Superintendent Scott's declaration regarding her interactions with the dog walkers is at odds with the contemporaneous evidence. In her declaration, she states that she believed the dog walkers had no on-going concerns about the closure:

On February 17, 2000, 1 personally met with Lydia Boesch, Lindsay Kefauver and Anne Farrow, representatives of the off leash dog walker groups and individuals, to discuss their concerns and further discuss the basis of the closures. I also explained that a Park Service regulation prohibited pets off leash in national park areas (36 C.F.R. Section 2.15) and that the park has an obligation to protect sensitive resources, such as the dunes and the bank swallows. This meeting went well, and within a few days, we received correspondence from both Ms. Farrow and Ms. Kefauver expressing their satisfaction with our meeting. They expressed no on-going concerns about the closure or requests for changes in the closure in that correspondence. True and accurate copies of this correspondence are attached hereto as Exhibits A and B (US06570 and US06125-26), respectively. None of my interactions with this group caused me to conclude that this small closure was highly controversial in nature.

(3d Scott Decl., Par.12). This statement is at odds with several parts of the record. First, less than a month before, Assistant Superintendent Scott instructed National Park Service staff not to encourage communication with the dog walkers:

(A.R. US06268, email from M. Scott to D. Mannel, J. Scheumann, Y. Ruan, and T. Thomas and copied to R. Scott, T. Fortmann, M. Bartling, dated Jan. 24, 2000). In addition, between the February 17 meeting and Assistant Superintendent Scott's March 3 justification memorandum, the dog walkers were actively opposing the closure. On February 25, counsel for plaintiffs faxed a letter to Ranger Fortmann stating that the recreational users of Fort Funston were considering applying for a temporary restraining order to prevent the closure. On March 1, a front-page story in the San Francisco Examiner quoted angry comments from dog walkers and noted that the dog walkers were going to seek an injunction. In that same article, Ranger Roger Scott admitted that "[w]e knew this was not going to be a popular thing," a statement he acknowledged under oath.

         The letters appended to Assistant Superintendent Mary Gibson Scott's declaration as Exhibits A and B, while pleasant in tone, did not suggest that the dog walkers were satisfied with the closure. In Exhibit A, Lindsay Kefauver thanked Assistant Superintendent Scott for meeting with the dog walkers and expressed hope that the National Park Service and the dog walkers would continue to talk about preserving off-leash privileges at Fort Funston:

(3d Scott Decl., 12, Exh. A, ltr. from L. Kefauver to M. Scott, Feb. 22, 2000). In Exhibit B, Anne Farrow expressed concern that the Ft. Funston Dog Walkers be a part of decisions concerning the park:

Please let me know who will be the GGNRA representative at our February 29 (7 pm) meeting as soon as possible. We need to be sure our clean-ups are organized for the next several months and be sure we are informed of and part of decisions affecting Fort Funston.

         C.         Highly Controversial Nature

Ranger Milestone showed you two areas, Battery Davis' hill slope erosion control project and the Bank Swallow critical habitat, both are management concerns. The swallow habitat restoration area is nearing its completion and will not be expanded southward. To protect the newly restored habitat, pets will be required on leash while passing through the Bank Swallow trial system.

These excerpts show an intent on the part of the National Park Service to railroad through the closure, to maintain secrecy, to unleash the fencing with lightening speed, and to establish a fait accompli.

         Second, contrary to the government's argument the closure affected a significant and strategically located parcel. The ten-acre closure should be viewed in terms of the 220 acres of Fort Funston, not the larger GGNRA. Otherwise, a closure within a multi-site park could never be considered of a "highly controversial nature." The closure must be considered in conjunction with the previous closure of the same type; otherwise, piecemeal closures could never be challenged even though large in overall scope. This parcel is especially significant. The closure encompasses beach-front land with important beach access and large sand dunes on which people exercise and play with their dogs. Put differently, plaintiffs are able to articulate objectively plausible issues about the closure that explain why the closure is legitimately highly controversial. It is a project whose details might well be modified by public input even if it goes forward.

         D.        Substantial Alteration in Public Use Patterns

         Two decisions have discussed the term "significant alteration in the public use pattern." In Mausolf v. Babbitt, 125 F.3d 661 (8th Cir. 1997), the snowmobilers sought to enjoin the National Park Service from enforcing restrictions on snowmobiling in Voyageurs National Park. The plaintiffs argued, inter alia, that the restriction should have been published in the Federal Register under Section 1.5(b) because it would result in "a significant alteration in the public use pattern." The Eighth Circuit rejected the argument. Snowmobiling in Voyageurs National Park was already generally prohibited absent special regulations permitting the activity. Id. at 669 n.10. The court reasoned that although the National Park Service had neglected to enforce the provision and had allowed snowmobiling to continue despite regulations to the contrary, the challenged closure order restricting snowmobiling did not amount to a "significant alteration" in what was previously an unlawful public use of the park. Ibid.

         In Spiegel v. Babbitt, 855 F.Supp. 402 (D. D.C. 1994), the court held that the National Park Service's decision to limit mooring hours in Georgetown Waterfront Park did not create a "significant alteration in the public use pattern." Without lengthy analysis, the court concluded that plaintiffs' arguments to the contrary were not sufficient to outweigh the deference a court normally grants to an agency decision. In Spiegel, the National Park Service had a written a letter to the plaintiff explaining that its limited docking restriction did not constitute a significant alteration of public use warranting publication in the Federal Register. Id. at 404. The District of Columbia Circuit affirmed this portion of the district court's order. Spiegel V. Babbitt, 56 F.3d 1531, No. 94-5184, 1995 WL 364555, *1 (D.C. Cir. May 31, 1995).

         Here, however, walking dogs off-leash in Fort Funston was expressly permitted (A.R. US01472, GGNRA, 36 C.F.R. 1, Compendium Amend., signed on July 8,1996, by Brian O'Neill, Gen. Superintendent). Thus, Fort Funston had the reverse scheme from Mausolf, which required special regulations to allow snowmobiling. The National Park Service's closure of the coastal bluff area was not simply enforcement of existing law. Likewise, this case differs significantly from Spiegel. There the court's decision rested solely on deference to the National Park Service, which had memorialized its decision that its restriction did not significantly alter the public use pattern in a letter. Here, as discussed above, deference to the National Park Service is not appropriate.

         Comments to the "significant alteration" language in Section 1.5(b) provide:

A permanent closure of a limited area within a park does not require the use of notice and comment procedures, unless it also has the required effect of significantly altering or disrupting use by a substantial number of park visitors. In this connection, it should be noted that a particular closure or restriction in a small park unit may require rulemaking, even though it would not if applied in a park with a different pattern.

Dated: April 26, 2000.