WASHINGTON – Thousands of recommendations that could save taxpayers tens of billions of dollars are gathering dust, the watchdog arm of the federal government says.

“That’s a lot of money,” Oklahoma Sen. James Lankford said in an interview.

Lankford, a Republican, highlighted the issue by holding a recent hearing of the Regulatory Affairs and Federal Management Subcommittee, which he chairs.

Federal agencies have not fully implemented 4,800 recommendations made by the U.S. Government Accountability Office within four years, according to a GAO report to Lankford’s panel.

They represent about one-fifth of all GAO recommendations and involve a range of programs and problems such as Medicare over-payments, long waits for Veterans Affairs services and fraudulent Social Security payments.

The worst at following through on money-saving changes, the GAO reported, is the Department of Defense. It has not fully implemented 1,000 recommendations. Its weapons-buying program has been considered at high-risk of waste since 1990, said the report.

Among wasted opportunities highlighted by the GAO was contracting for a series of near-shore combat ships by the U.S. Navy, even though the ships have not been shown to be able to handle rough water or shock. The Navy only “partially agreed” with the recommendations to do more tests before ordering more ships, the report said.

The Defense Department did not respond to an inquiry about the GAO’s recent report.

Among other recommendations that haven’t been followed:

> Auditors recommended in 2012 that the Centers for Medicare and Medicaid Services change accounting methods after over-paying private health plans between $3.2 billion and $5.1 billion from 2010 to 2012.

The centers only said they would “take our findings into consideration,” the GAO said.

Medicare also hasn’t taken the steps necessary to get off GAO’s “high-risk” list, where it has been included since 1990, the report said.

> The Social Security Administration hasn’t caught up on reviews of thousands of disability cases to see if recipients still qualify for benefits.

In 2012, the GAO found reviews of 24,000 cases were at least six years – in some cases, more than 13 years – overdue. One-quarter of those cases involved children who were expected to improve within 6 to 18 months after qualifying for benefits.

The GAO said the government could save $3.1 billion over five years if it does all the reviews.

> The Department of Veterans Affairs hasn’t implemented more than 100 recommendations to improve service, the GAO said. It recommended improved training, clearing up ambiguous processes and better oversight.

Agencies that heeded the GAO’s advice saved $74.7 billion last year, according to the report. Among the changes they made was the elimination of direct subsidies to farmers based on historical yields, instead of whether they actually are planting crops.

In 2012, the GAO found about 2,300 farms receiving payments even though their land was reportedly “fallow.”

Agencies have a “too cavalier” attitude about findings by the government’s watchdog,  Sen. Heidi Heitkamp, D-North Dakota, said at the hearing in December.

They think “we may have a bad hearing on the Hill, but we’ll get over it and move on with our life,” said Heitkamp, the subcommittee’s ranking Democrat.

Gene Dodaro, the GAO’s comptroller general, said agencies generally agree with the recommendations.

Their follow-through “may not be at the level of intensity you want,” he told lawmakers.

Steve Ellis, vice president of Taxpayers for Common Sense, noted in a statement that GAO works for Congress, which should demand compliance.

Otherwise, he said lawmakers “are undercutting their own investment.”

“It is disappointing but not that surprising that agencies are slow to implement some of the GAO recommendations. In some cases it would require a change of agency culture, in others it would be tantamount to admitting error, and in others it may offend some well entrenched special interest,” he said.

Heitcamp said lawmakers should press nominees for department-head posts to agree during confirmation hearings to implement any outstanding GAO recommendations.

Lankford said the GAO should send progress reports to the appropriations committees that hold agencies’ purse strings.

He’s also pushing a bill requiring the government to publish a list of programs, their costs and how they’re performing, so that taxpayers can see where their money goes.

“There’s a sense that there’s nothing that can be done about the deficit, and I wanted to show there is,” he said of the hearing.

Some agencies say they’re trying.

Social Security Administration spokeswoman Nicole Tiggemann said the agency didn’t receive additional funding it requested to do reviews of disability benefits cases in 2012 and 2013.

It received funding in 2014 and was able to review more than twice as many cases involving children in the past year as it had the previous year and four times as many as in 2013.

Veterans Affairs spokeswoman Walinda West said the GAO’s report comes at a critical time for the agency, when it realizes it needs to make “significant improvements.”

The department began trying to improve customer service in 2014, including improving staff training and revamping the website that veterans use to access services.

Kery Murakami is the Washington, D.C., reporter for CNHI’s newspapers and websites. Reach him at kmurakami@cnhi.com.