More than 1,000 D.C. police officers will become eligible to retire in the next five years, the beginning of a "retirement bubble" that has some officials concerned with the department's ability to keep up with the departures.

A host of sworn police officers hired in the 1980s and early '90s will become eligible to retire soon as they meet two requirements -- officers hired during that time must be at least 50 years old and have served on the force for at least 25 years.

"We are really going to be struggling in the next five years," Police Chief Cathy Lanier said in November on NewsChannel 8's "NewsTalk" program.

Overall, 1,042 sworn officers will become eligible for retirement between now and 2017, including 354 officers in 2015, according to projections provided by the Metropolitan Police Department. By comparison, an average of 90 officers became eligible to retire each of the past three years.

While not all officers leave the department as soon as they're eligible, those numbers don't account for officers who resign, retire due to a disability or are fired from the department, according to police spokeswoman Gwendolyn Crump.

And the longer an officer stays on the force, the bigger the retirement bubble grows as retirement-eligible officers carry over year to year, she said.

About 400 officers, or approximately 10 percent of the 3,866 sworn officers currently on the force, are eligible to retire right now, according to Kris Baumann, the head of the city's police union.

The number of separations from the department rose in fiscal 2012, when 204 sworn officers left the force after an average of 175 officers left in each of the previous five years, Lanier wrote in a letter to D.C. Council Chairman Phil Mendelson.

Lanier wrote that the department is at least funded to keep pace with attrition through the current fiscal year.

But the number of officers leaving is growing, according to Baumann. Twenty-five officers left the department in October, and another 26 left in November, he said.

If that many officers continue to leave every month, "you can throw all our predictions out the window," Baumann said. "Even if we react now, we're way behind the curve at this point."

The council rejected two proposals by Mayor Vincent Gray last month that would have funded hiring 100 new officers, including a plan to tie speed-camera revenue to fund 52 officer positions.