WASHINGTON (AP) — Environmental Protection Agency Administration Lisa Jackson says she's stepping down after nearly four years on the job.

Jackson announced her departure in a statement Thursday. She gave no particular reason for leaving but said she was ready for new challenges, time with her family and new opportunities to make a difference.

Jackson's tenure was marked by high-profile brawls, including the fight over whether hydraulic fracturing was causing groundwater pollution in the tiny Wyoming community of Pavillion

She says she's leaving the agency, in her words, "confident the ship is sailing in the right direction."

Jackson is expected to leave after the State of the Union address in late January. Cabinet members looking to move on often leave at the beginning of a president's second term.