Departing Chairman Glenn McCullough says the Tennessee Valley Authority is stronger than when he arrived in 1999.
But the former mayor of Tupelo, Miss., says the nation's largest public utility still faces financial, environmental and competitive challenges.
The 50-year-old McCullough leaves the TVA on Wednesday as the 12th and final full-time chairman in the 72-year history of the federal agency.
McCullough doesn't know his future plans or if he will be on an expanded part-time board that is being created after he leaves.
Senate Majority Leader Bill Frist pushed the board restructuring to make the group more open and responsive. But the White House has yet to name nominees.