Mary Frances Callan, embattled superintendent of the Palo Alto Unified School District, Friday announced plans to retire in 2007, effective Aug. 30.

Callan said her retirement is according to a "five-year plan" she had when she joined the district in January 2002.

She said she leaves with mixed emotions, but that when she arrived at the district "I made it clear I was committing to a five-year tenure. I realized this summer that I was about to reach that five-year mark."

She said she "also realized that, given the current extended timelines for superintendent searches, I would need to let you know of my plans prior to 2007 so that the Board would have sufficient time to find my replacement."

Callan informed school board members through a 2 1/2-page letter she delivered personally to school board President Mandy Lowell, attending the California School Boards Association meeting in San Francisco, while staff members notified school administrators, teachers and staff. (See full text of letter in separate link.)

For most of the letter, Callan cited successes she felt the district has had in recent years. She did not mention the controversy relating to leadership and trust issues raised by middle managers in the district, members of the "management team" of principals, vice principals, program directors and some school psychologists.

School board President Mandy Lowell said the district "is fortunate to have the lead time to do a complete search," and that it will be a national search.

"We will find an outstanding superintendent and, if that person can afford the housing prices in Palo Alto, we will continue to have outstanding leadership in the district," Lowell said.