Correction appended Oct. 29

Vice President Joe Biden, his wife and 11 other family members spent four nights on vacation this August at a lakeside log cabin overlooking the snowcapped peaks of Mount Moran in Grand Teton National Park.

The four-bedroom Brinkerhoff Lodge, where they stayed, is owned and operated by the National Park Service. Under a policy adopted in 1992, after controversy over VIPs using the cabin for vacations, the National Park Service banned purely recreational activities by federal employees at the property, restricting its use to "official purposes." But in recent years, the park service has interpreted that same rule so broadly as to again allow senior officials to take cheap vacations in Grand Teton with friends and family.

While visiting the park, Biden held no events, kept no public schedule, and his staff initially declined to answer a reporter's question about where he spent the night. Last week, after TIME uncovered documents confirming his stay at the lodge, Biden's office said the Vice President planned to personally reimburse the park $1,200 for "renting the Brinkerhoff" for his family's vacation.

Under park service rules, the lodge is maintained for use by federal employees for "training and official conferences" and for those on "temporary duty in the park." In practice, the superintendent of Grand Teton National Park, who has discretion over whether to demand payment for the lodge, has interpreted those rules to allow extended family vacations if there is an element of official business involved.

A Grand Teton National Park spokeswoman, Jackie Skaggs, said last week the Biden family visit met the internal criteria, since the Vice President received an official park briefing and tour while staying at the lodge. “With few, if any, exceptions, officials who stay at the Brinkerhoff are given in-depth briefings and/or issue tours,” she wrote in an email to TIME.

But that explanation may not stand. In response to further questions from TIME, the Interior Department said Tuesday that it was launching an investigation into how the park service has managed the Brinkerhoff. "In light of inconsistencies in billing practices and ambiguity in the policy at the park, the Interior Department has directed the National Park Service to conduct an immediate review of compliance with the policy and related recordkeeping and to seek reimbursement, where appropriate, for use of the Brinkerhoff," wrote National Park Service spokeswoman April Slayton in an email to TIME.

A Favorite Vacation Spot

Biden is not the only senior member of the Obama Administration who has taken advantage of the Brinkerhoff in recent years for family vacations or getaways with friends. Records obtained by TIME through the Freedom of Information Act show that at least four cabinet-level officials, a deputy White House chief of staff and the director of the Park Service have made use of the lodge with friends and family since 2011.

Former Environmental Protection Agency Administrator Lisa Jackson stayed three nights in 2011 with her husband, and five other people, including a person listed as a friend. She received a tour of a new air quality monitoring station, according to a park official.

Former Transportation Secretary Ray LaHood traveled there in 2012 for eight nights with his wife, his daughter-in-law, three grandchildren, two other adults and his son, Illinois State Sen. Darin LaHood. He attended the Department of Transportation grant award event, according to LaHood's office.

Education Secretary Arne Duncan stayed there for six nights with his wife and children in 2013. He attended a nearby roundtable with tribal leaders and an event at a local school, according to the Department of Education.

Former Secretary of Interior Ken Salazar, who oversaw the National Park Service, stayed there with his family for three nights in 2011. His office did not return a call about the purpose of his visit.

Former White House Special Advisor Phil Schiliro also used the lodge for one night in August of 2011 with his wife and one other person. The White House did not return emails about the purpose of his visit.

National Park Service Director Jon Jarvis, his wife, his son and his son’s girlfriend stayed for five days in August of 2012. The park service said he had official business on two of the five days. " The director took personal time during the remaining days," a spokesperson said in a statement.

Under federal policy, family members may accompany government employees who travel on official business. "Family members’ travel costs and incidental expenses are not typically reimbursed by the federal government, although they may stay in the accommodations reserved for the traveling employee, as long as any additional costs incurred as a result of the stay are covered by personal funds," wrote National Park Service spokeswoman Slayton.

Confusion Over The Rules

The offices of several officials who stayed at Brinkerhoff, including the Vice President, Duncan and LaHood, said there was initial confusion over their need to pay for extended stays at the lodge with family members.

Under National Park Service policy, "a bill of collection will be prepared" for those who visit the Brinkerhoff on "project related travel that will be billed to another entity." The Freedom of Information Act request returned no documents showing that any bills had been issued. The park service also produced no records of official stays at the Brinkerhoff between 2000 and 2010.

A spokesperson for the Vice President, who declined to be named, said Biden's office was still waiting for an invoice from the park two months after the stay, when TIME made inquiries. “The office understood from the park service that personal use would cost the local per diem rate," the spokesperson said, referring to the a schedule of overnight hotel costs maintained by the General Services Administration for a single hotel room. Biden's office said the Vice President will now personally pay $1,200 for the four nights, a figure that includes an extra $10 per night for each additional member of his family.

That cost, which assumes that a four-bedroom lodge is comparable to a single hotel room, is far below market rate for other nearby accommodations, especially during peak summer tourism season. At the nearby Jackson Lake Lodge, a two-bedroom cabin that sleeps four without a view of the lake, averages $250 a night in August. Nearby homes outside the park can rent for more than $1,000 per night during the summer.

A spokesperson for the Department of Education says the park service “never conveyed” to Duncan that he would have to pay for the non-official portion of his family’s nearly week-long stay. “Secretary Duncan requested an invoice for his family’s stay and will reimburse the park fully for the time he was on personal leave,” the official said.

A spokesperson for LaHood, who is now a policy adviser at a law firm, said he made a donation to the park at the time of around $250 after consulting with Salazar. LaHood has since asked the park if he is obligated to pay more.

With the exception of a $150 check from Salazar, the park service has no record of any payment from other officials for their stays, though Skaggs said charges are sometimes directly billed to other government offices and that the park doesn’t maintain records of those transactions.

There is evidence, however, that the park service is now trying to improve its management of the Brinkerhoff, at least on the public relations front. After being contacted by TIME, a computer with an IP address registered to the National Park Service made alterations to the Wikipedia page for the Brinkerhoff Lodge.

A phrase describing the property as a "vacation lodge" was changed to "historic lodge." A phrase noting the Brinkerhoff's history as a destination for "VIP housing" was deleted.

A Controversial History

Located on the banks of Jackson Lake with views of the glacier-strewn peak of Mount Moran, the Brinkerhoff Lodge was built in 1947 by the family of Zachary Brinkerhoff, a prominent Wyoming oil company executive. It features a two-story living room, a full-length deck, Western-style chandeliers and interior walls lined with log or knotty pine paneling.

After it was acquired by the National Park Service in the 1950s, the lodge became one of several “VIP” properties across the country, which were used by presidents, members of Congress and government bureaucrats. The park service curtailed their use following public outcry in the late 1980s and early 1990s. "The Secretary has concluded that the public interest will be better served by having the four existing VIP accommodations used only for official purposes," reads a memorandum by former Parks Service director James M. Ridenour, which remains in effect. "As of February 10, 1992, these sites will no longer be available as VIP accommodations."

All but the Brinkerhoff were eventually converted to other uses. The Bodie Island Cottage, a three-bedroom lodge that sleeps 11 just off the beach below the Cape Hatteras Lighthouse in North Carolina, was turned into a ranger station. Little Cinnamon House in Virgin Islands National Park, where former President Jimmy Carter stayed for nearly two weeks after his 1980 electoral defeat, was turned into employee housing, and “is currently in disrepair and uninhabited” according to park service officials. Camp Hoover in Virginia’s Shenandoah National Park, once a favorite of members of Congress with sweeping views of the Blue Ridge Mountains, was converted to a museum in 1996.

The park service maintains that it is cheaper for the federal government to house officials at the Brinkerhoff on official travel because it costs less than nearby hotels.

“Historic structures are better maintained when they are actively used and the park has determined that seasonal use of the Brinkerhoff will better protect this valuable historic facility,” Skaggs said. “By allowing officials and governmental employees access to occasional overnight stays in the Brinkerhoff, the park is able to fund the long-term maintenance of this historic structure.”

She added that the fees, when collected from stays at the Brinkerhoff, are earmarked for preserving the building.

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Correction: The original version of this story incorrectly identified Phil Schiliro's former title. He was an assistant to the President and special advisor.