WASHINGTON (AP) — Trying to get a handle on hundreds of sensitive, closely held surveillance programs, a Senate committee is compiling a secret encyclopedia of American intelligence collection. It’s part of an effort to improve congressional oversight of the government’s sprawling global spying effort.

Sen. Dianne Feinstein launched the review in October 2013, after a leak by former National Security Agency systems administrator Edward Snowden disclosed that the NSA had been eavesdropping on German Chancellor Angela Merkel’s cellphone. Four months earlier, Snowden had revealed the existence of other programs that vacuumed up Americans’ and foreigners’ phone call records and electronic communications.

“We’re trying right now to look at every intelligence program,” Feinstein told The Associated Press. “There are hundreds of programs we have found … sprinkled all over. Many people in the departments don’t even know (they) are going on.”

Feinstein and other lawmakers say they were fully briefed about the most controversial programs leaked by Snowden, the NSA’s collection of American phone records and the agency’s access to U.S. tech company accounts in targeting foreigners through its PRISM program. Those programs are conducted under acts of Congress, supervised by a secret federal court.

But when it comes to surveillance under Executive Order 12333, which authorizes foreign intelligence collection overseas without a court order, there are so many programs that even the executive branch has trouble keeping track of them, Feinstein said. Many are so sensitive that only a handful of people are authorized to know the details, which complicates the management challenge.

Lawmakers who serve on the intelligence committee sometimes have difficulty making sense of the information they receive, some of which can’t be shared even with some of their own staff.

Director of National Intelligence James Clapper has joked that only one entity in the universe has complete visibility over all the U.S. government’s secret intelligence programs — “That’s God.”

Feinstein, a California Democrat, initially wasn’t sure that Sen. Richard Burr of North Carolina, who took her place as chairman of the panel when Republicans took control of the Senate in January, would agree to continue the review. But Burr and Feinstein recently reached an agreement to do so, said Senate aides. They were not authorized to discuss the inner committee workings publicly and spoke only on condition of anonymity.

Two executive branch officials who had been detailed to the committee are returning to the executive branch and will not be replaced, the aides said, so the effort will be entirely the work of congressional staff. The project will end in September, the aides said.

Burr declined to comment. His spokeswoman, Rebecca Glover Watkins, said in an email that the committee “is constantly and continuously engaged in oversight of intelligence community activities. It is the very core of what the committee does, day in and day out, and it is a key component of the work done by the committee’s professional staff.”

Feinstein initiated the review, she said, after she and other lawmakers were taken by surprise by the revelation that the NSA was spying on the leader of a close ally.

At the time, Feinstein said the intelligence committee, which is regularly briefed on spying programs, had not been “satisfactorily informed,” about some NSA surveillance. “Therefore our oversight needs to be strengthened and increased.”

After that disclosure, President Barack Obama ordered his own review of NSA surveillance that resulted in the termination of some eavesdropping on the leaders of certain unidentified friendly countries.

The review will allow lawmakers to maintain and access information on all the programs, but will avoid creating a single document that amounts to a roadmap to American surveillance, said U.S. officials. They were not authorized to be quoted because some details are classified. Although the Senate intelligence committee has vaults, safes and secure computer networks, officials do not want to risk leaving such a file in the custody of the Senate.

If senators object to any of the surveillance, they can raise the issue in secret with Obama administration officials. They can’t force a change, but they can use their influence over legislation, budgets and nominations to press for it.

However, that influence has its limits, as Sens. Ron Wyden and Mark Udall discovered when they sought to warn about some of the NSA collection that Snowden ultimately leaked. They could not make their warnings clear enough without disclosing secrets.

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