WASHINGTON — The decision by the Trump administration to move the Washington headquarters for the Bureau of Land Management to Grand Junction, Colo., last year left the agency with high vacancies as veteran employees — especially African Americans — quit rather than move, a government watchdog said in a report issued this week.

Senior officials at the Department of the Interior under former President Donald J. Trump had argued the move was needed to ensure that top bureau employees would be closer to the federal land the agency manages, most of which is in the western half of the country.

But the report from the Government Accountability Office was critical of the decision, saying that the agency lacked a “strategic work force plan” that could have guided its decision-making. As a result, the report found that the headquarters move caused many staff to quit rather than relocate to Colorado.

Out of a total headquarters staff of about 560 people, 134 people left the agency after the move was announced in 2019. Of the remaining staff, 176 were asked to relocate, but 135 refused, according to the report.

The report, which was first obtained by The Washington Post, said other decisions by the agency at the same time, including changes to its organizational structure, led to further departures and an increased reliance on “details,” which are employees from other agencies temporarily assigned to perform the duties of a position that has been vacated.

The result, the report said, was a “loss of headquarters staff, increased numbers of headquarters vacancies, loss of experienced staff, and decreased representation of employees of some races and ethnicities. Increased vacancies, and the details used to temporarily fill those vacancies, sometimes led to confusion and inefficiency.”

In September, Deb Haaland, the current Secretary of the Interior, announced that she had decided to reverse the decision by the Trump administration to move the B.L.M. headquarters to Colorado.

But the report by the G.A.O. had already been requested by Representative Raúl Grijalva, Democrat of Arizona and the chairman of the Committee on Natural Resources in the House. Mr. Grijalva asked the accountability office to examine changes in the work force at the bureau in the wake of the decisions by members of the Trump administration.

Authors of the government report said it was difficult to assess the full impact of the move of the headquarters and the other changes on the 8,800-person agency because officials did not maintain comprehensive data about vacancies and other personnel issues.

The report said there was only a minor change in the racial and ethnic makeup of the overall agency after the headquarters move.

Before the move, about 83 percent of the agency’s employees were white, about 8 percent were Hispanic, about 3.3 percent were Black and the rest were Native Americans, Asians or others. After the move, the makeup was: 80 percent white, 9.5 percent Hispanic, 3.1 percent Black and a slightly larger share for the other racial and ethnic groups.

But the report found that the changes in the racial makeup of the headquarters staff was much more significant.

Before the move, Black employees made up more than 21 percent of the staff at the B.L.M. headquarters, perhaps reflecting the population of Washington D.C., which is about 45 percent Black according to the 2019 census. After the move to Colorado, the racial makeup was different, the report said.

“By January 2021, after the relocation was completed, the number of Black or African American headquarters staff decreased by more than half, making up 12 percent of total headquarters staff,” the report said.

The authors of the report urged the agency to do a better job of tracking vacancies throughout its work force in order to allow them to better understand the impact of decisions by its leadership.

They also recommended that the agency’s senior officials create a strategic plan to guide them on future changes to its personnel.

“B.L.M. does not have complete and reliable data on vacancies and details, and, therefore, does not have a complete picture of its staffing needs,” the report concluded. “Without such data on vacancies and details across the agency, B.L.M. officials do not have complete information to make decisions about filling vacancies and initiating details to help the agency achieve its mission and goals.”

Officials currently at the B.L.M. said in their response to the report that they intend to make those changes.

“Moving forward, the B.L.M. intends to establish a more standardized process to track vacancies and detailees bureau-wide,” Laura Daniel-Davis, the principal deputy assistant secretary for Land and Minerals Management, wrote in the agency’s response.

She added that the B.L.M. is “currently in the process of developing a process for bureau-wide strategic work force planning.”