The Defense Department is paying the salary of a Marine officer who has been assigned to the personal staff of Sen. Roger W. Jepsen (R-Iowa) to help Iowa businesses obtain Pentagon contracts.

Under the arrangement, reported yesterday by Congressional Quarterly, Lt. Col. James E. Secrist is continuing to draw his officer's pay of about $45,000 a year while he is detailed to Jepsen's staff for an indefinite period.

Jepsen is chairman of the Armed Services subcommittee on manpower and personnel, which sets employe ceilings for each military branch and has jurisdiction over military pay and benefits.

Secrist joined Jepsen's staff July 1 after the senator sought and received permission from Navy Secretary John F. Lehman Jr. for the arrangement, according to James Lafferty, Jepsen's press secretary. Lafferty said Secrist had been a Pentagon liaison officer who worked with Jepsen's subcommittee.

"We needed someone on our staff who was familiar with defense procurement contracts and procedures," Lafferty said. He said Secrist had helped the subcommittee and "has responded to queries from Iowa business people about defense contracts."

Lafferty said Jepsen sees no conflict of interest in having the Pentagon pay Secrist's salary, nor does he think the arrangement gives Iowa contractors an unfair advantage. "I just don't see where it would be a problem," Lafferty said. "It may indicate that Iowa residents have a senator that has a lot of initiative."

Navy spokesman Lt. Tom Yeager said that "although it's an uncommon practice, it's not unprecedented" for officers to be detailed to congressional staffs.

Pentagon rules say that such assignments are "generally not favored" unless they further "specifically identifiable interests of the Department of Defense," Congressional Quarterly reported. Yeager said the practice gives military officers a valuable chance "to see the inside picture on how the legislative process works."

"We rely on the senator's good judgment and on Col. Secrist's good judgment not to assign or accept any jobs that would place him in a compromising position," Yeager said.

He said that each military service has an office to help small business, and that Secrist would not be giving Iowa companies any information "that they wouldn't be able to get by calling the department."