The trickle of budget cut-induced furlough notices going to federal employees turned into a steady flow in recent days, on Thursday lapping at the doors of the government’s central budget agency itself.

The Office of Management and Budget, which has been guiding agencies on furloughs and other fallout from sequestration, told its own employees that they are to be put on unpaid leave for 10 discontinuous days, starting the week of April 21 and continuing into early September.

“At this time we do not reasonably anticipate the need for furlough beyond 10 work days,” Acting Director Jeffrey Zients said in the notice.

Also on Thursday, U.S. Customs and Border Protection sent out furlough notices, which as the agency earlier had said will impose 14 intermittent unpaid days off. They also are to start the week of April 21.

“It is clear that moving forward, sequestration will take a particularly heavy toll on CBP’s trade-related mission, resulting not just in longer wait times at the border, but in the loss of perishable goods and a constricted flow of commerce,” said a statement from the National Treasury Employees Union, which represents CBP employees.

The Federal Aviation Administration on Tuesday notified its employees that they will be furloughed for 11 discontinuous days beginning the week of April 7.

“Please know that I sincerely regret the impact that even a single furlough day will have on you,” FAA Administrator Michael P. Huerta said in an e-mail to employees.

Doug Church, spokesman for the National Air Traffic Controllers Association, said in an e-mail: “We continue to implore Congress to act now to stop the very negative effects of these budget cuts before they take full effect. This does not need to happen. Travelers may face unneeded delays and the closure of nearly 200 towers would be very bad for the aviation system and the economy and communities that depend on those airports.”

And on Monday, the Environmental Protection Agency sent notices of 13 potential furlough days, requiring employees to take four of them through June. After that, the agency will reevaluate whether it will need to impose the other nine days.

Furlough notices specify that employees cannot work without pay voluntarily, nor can they substitute paid leave such as vacation time for unpaid furlough days. The notices trigger a 30-day waiting period during which employees can respond and have access to agency documentation. However, making a response does not delay a furlough, nor does bargaining, which is allowed on limited matters in unionized workplaces.

Even before sequestration started March 1, the Justice Department notified some employees of an expected 14 days, and the National Labor Relations Board sent notices to all employees anticipating 22 days.

Numerous other agencies have said they expect to impose furloughs but have not yet issued formal notices. The largest, the Defense Department, anticipates sending notices around March 15 telling employees that it will need to impose 22 days, to be spread out as one day a week from late April through September. The IRS has said it expects five to seven days but won’t impose them at least until summer.

Several agencies, including the Government Accountability Office and the Agency for International Development, have said they will not need to impose furloughs, while the State Department has said it will not need them at least through June. Self-funding agencies such as the U.S. Postal Service are not affected by sequestration, while the Veterans Affairs Department is exempt by a separate law.