Jack E. Ravan, head of water programs at the Environmental Protection Agency, will leave Washington in late April to take over as regional EPA administrator in Atlanta, the agency announced last week. The current regional administrator, Charles W. Jeter, will become a special assistant to the EPA's policy office, in charge of an agency ecology laboratory in Athens, Ga. Ravan was named assistant administrator for water programs in 1983, shortly after most of the agency's top leadership left in a controversy over the management of hazardous-waste issues. Agency officials said the move was prompted by Ravan's desire to return to Atlanta, where he served as head of the EPA regional office from 1971 to 1977.

David Newhall III has been named principal deputy assistant secretary of Defense for health affairs. Newhall served as chief aide to Richard S. Schweiker when he was a senator and secretary of Health and Human Services. After Schweiker resigned from HHS in 1983, Newhall left to operate a farm and an ornamental fencepost business on an old plantation in Virginia.

Former Interior secretary William P. Clark has joined the law firm of former secretary of State William P. Rogers in an "of counsel" role. Clark will work part time for the New York firm, Rogers and Wells, in its Los Angeles office and plans to visit its Washington office about once a month. Clark also will be taking on occasional projects for the White House. He is now at work on a task force, along with Jeane J. Kirkpatrick and James R. Schlesinger, studying management of nuclear weapons programs.

Mari Maseng, assistant secretary for public affairs and Elizabeth Hanford Dole's chief spokesman at the Transportation Department, is planning to join Beatrice Companies Inc., a consumer goods holding company, in April as vice president for corporate affairs. She was formerly a speech writer for Reagan.

Reagan has nominated Donald E. Shasteen to the post of assistant secretary of Labor for veterans' employment and training programs. Shasteen, 56, has served since 1981 in the department, the last two years as the deputy assistant secretary.