The head of the Minerals and Management Services (MMS) has resigned.

MMS, which is charged with monitoring and regulating offshore drilling, has come under intense criticism since the explosion of the Deepwater Horizon in the Gulf of Mexico.

Interior Secretary Ken Salazar told a House panel this morning that Director Elizabeth Birnbaum had stepped down.

“She did it on her own terms and her own volition,” he said at a House Appropriations Committee hearing.

Salazar called Birnbaum “very strong and very effective” and said she had helped to implement reforms at the long-troubled agency. Birnbaum has helped to address a “culture of corruption,” Salazar said.

“Liz Birnbaum has been a strong leader, and we have done tremendous work,” he said.

Birnbaum has held the post since July of 2009.

“I’m grateful to the President and to the Secretary for allowing me to serve this Administration and the country,” Birnbaum said in a statement.  “It’s been a great privilege to serve as Director of the MMS.  I have enormous admiration for the men and women of the MMS who do a difficult job under challenging circumstances.  I’m hopeful that the reforms that the Secretary and the Administration are undertaking will resolve the flaws in the current system that I inherited.”

A report released earlier this week revealed MMS employees had accepted numerous gifts from oil companies and had viewed pornography on government computers. At least one inspector had used meth.

The report -- the latest in a years-long series of negative reports about the agency -- addressed misconduct that occurred under the Bush administration. Salazar has asked the inspector general for a new study that explores the agency since he implemented ethics reforms.

MMS has also come under fire for allegedly lax environmental oversight under both the Bush administration and President Barack Obama -- including its approval last year of the BP drilling project that went catastrophically awry in the Gulf of Mexico.

The Obama administration is reviewing the agency's environmental analysis process, and has also asked Congress to lengthen the time it has to review company drilling plans before granting permits.

Salazar has decided to split MMS into three branches. Birnbaum is not expected to be assigned to any of those agencies.

When announcing the splintering of the agency earlier this month, Salazar declined to directly address Birnbaum's role.

Rep. Nick Rahall (D-W.Va.), chairman of the House Natural Resourices Committee, said he was not satisfied that Birnbaum's resignation would change the culture of the agency.

“The departure of Elizabeth Birnbaum from MMS does not address the root problem. She has only been the public face of MMS for 11 months and the most serious allegations occurred prior to her tenure. This might on the surface be a good start but must not be the end game," Rahall said.