WASHINGTON — Since the discovery of 47 improperly placed grave markers at Fort Sam Houston National Cemetery in Texas in 2011, government audits have found more than 150 additional mismarked military graves nationwide, and the National Cemetery Administration has tightened its procedures, Veterans Affairs Department officials told a House panel Wednesday.

In October 2011, the NCA, which maintains 131 national cemeteries and 33 soldiers’ lots and monument sites under VA, independently reviewed all its burial sites, but VA’s Inspector General found “the audit lacked impartial and independent procedures and found that the timeframe … did not take into account the various sizes of national cemeteries.”

The audit discovered seven errors from a sample of 200 randomly chosen gravesites. Upon further review, the NCA found 146 more errors. VA maintains more than 3 million gravesites, noted Steve Muro, undersecretary for memorial affairs.

Rep. Jon Runyan, R-N.J., chairman of the House Veterans’ Affairs Committee’s disability assistance and memorial affairs panel, praised the progress being made at Arlington National Cemetery, where it was discovered that a number of graves were mismarked, bodies were buried on top of each other, and graves were too shallow. There also were allegations of financial wrongdoing.

Muro told Runyan that the NCA achieved a 96 percent approval rating for its quality of service in 2012.

Nevada Rep. Dina Titus, ranking Democrat on the subcommittee, noted that considering the number of gravesites, “it’s pretty remarkable that the number of mistakes you found were so low.”

Kathryn Condon, executive director of Army National Cemeteries Program, noted that Arlington National Cemetery became the first geospatially managed cemetery in March 2012, helping ensure more accurate mapping of the graves.

“The [geographic information system] helps synchronize all phases of our operations, from scheduling to headstone placement to authoritative documentation,” Condon said.

The new GIS technology allowed the creation of ANC Explorer, a web-based application launched in October that allows viewers to locate loved ones’ gravesites, capture their headstone or monument, and receive directions to their desired site.

Overseas sites such as the Pointe du Hoc Ranger Monument in France also are embracing new technology. The American Battle Monuments Commission, which oversees foreign monuments to fallen soldiers, launched its first mobile app in December. It is similar to the ANC Explorer.

ABMC Deputy Secretary Raymond Wollman said the app continues to ensure the achievement of the commission’s mission: “Keep the headstones white; keep the grass green; and tell the story of those we honor.”

Titus noted that 11 states lack national cemeteries, including her home state of Nevada.

But, Muro said, “approximately 90 percent of the veteran population — about 20 million veterans — has access to a burial option in a national state, or tribal veterans cemetery within 75 miles of their home.”