BOISE, Idaho — Interior Secretary Dirk Kempthorne defended his two-year tenure in Washington, D.C., saying it was highlighted by ethics reforms he hopes will improve the agency’s integrity after a slew of scandals.

The former Idaho governor, who took national office in May 2006 after Gale Norton’s departure, spoke here Monday in what he called his “last formal speech” as a Bush administration cabinet member. U.S. Sen. Ken Salazar, D-Colo., has been nominated by President-elect Barack Obama to replace Kempthorne.

The past two years have seen news accounts of Interior staffers who have been found to have improperly interfered with Endangered Species Act decisions; have been convicted of lying to Congress; and have been discovered to have had sex with oil-industry executives, as well as using cocaine and marijuana. Most of this activity took place while Norton headed the office, between 2001 and 2006.

Kempthorne said he’s installed a new ethics officer, has stressed the importance of recording discussions on potentially dicey matters in an ethics logbook, made an ethics DVD required viewing for new employees and fired employees involved in the worst of the transgressions.

“Without question, there have been a variety of issues concerning the integrity and activities of certain aspects of the Department,” Kempthorne, Idaho’s governor from 1999 to 2006 and Boise’s mayor for eight years starting in 1985, told more than 200 people at a City Club speech.

“We have endeavored to create an atmosphere and culture of ethics in the department, which is critically important,” he said. “I tell them, ’My mantra is, if in doubt, don’t.”’

Julie MacDonald, a deputy assistant secretary overseeing the U.S. Fish and Wildlife Service until her resignation in May 2007, was found to have exerted improper political interference on nearly every decision made on the protection of federally endangered species over five years.

Also, Steven Griles, a former Norton deputy, in June became the highest-ranking Bush administration official convicted in the Jack Abramoff lobbying scandal. He was sentenced to 10 months in prison for lying to the U.S. Senate.

And in September 2008, an Interior Department Inspector General probe found a “culture of substance abuse and promiscuity” in Interior’s Denver Minerals Management Service office, in charge of collecting billions of dollars in federal oil royalties. From 2002 through 2006, some staffers there were having sex with oil company personnel and using cocaine and marijuana, the report said.

For much of the last eight years, the Department of Interior, whose 73,000 employees oversee the federal Endangered Species Act, a fifth of U.S. territory and 391 national parks, has been lambasted by environmental groups as an agency where politics and power trumped good policy.

“The Department of the Interior has been a place where the interests of private companies supersede sound science and the public interest,” said Charles Clusen, a senior analyst at the Natural Resource Defense Council, in Washington, D.C.

Clusen criticized recent Bush administration-issued changes to Endangered Species Act regulations that environmentalists say would, among other things, block the law from being used to combat global warming. The changes, which also eliminate some of the independent reviews government scientists do on dams, power plants and timber sales, take effect this month, just as Obama takes office.

Kempthorne disputed the contention that his office has rushed modifications late in Bush’s final term.

He said he gave ample warning about the impending Endangered Species Act changes when he listed the polar bear as a threatened species in May due to receding sea ice, but refused to endorse the 1973 law as an instrument to regulate climate change. His role as the Bush administration winds down was akin to that of a quarterback in the waning minutes of the Super Bowl, he said.

“If you’re to play in the entire game, you’re to do what you’ve been asked to do,” Kempthorne said. “Until Jan. 20, I am the secretary of Interior and I work for you. And I’m not just going to sit on the sidelines.”