Environmental Protection Agency Administrator Lisa Jackson has announced her resignation after four years at the EPA. Jackson’s tenure was marked by controversial policies involving a number of high-profile issues including global warming, the Keystone XL pipeline, and emissions controls on coal-fired plants. And recent scrutiny over Jackson’s use of an alias e-mail account has led some to believe that her resignation was inevitable.

Jackson plans to step down after the president gives January’s State of the Union speech. In a prepared statement, she said, "I will leave the EPA confident the ship is sailing in the right direction, and ready in my own life for new challenges, time with my family and new opportunities to make a difference."

While Jackson does not provide a specific reason for her resignation, many analysts believe that it is a result of the never-ending controversy surrounding her policies at the EPA.

The New York Daily News reports,

Jackson, the agency’s first black administrator, constantly found herself caught between administration pledges to solve controversial environmental problems and steady resistance from Republicans and industrial groups who complained that the agency’s rules destroyed jobs and made it harder for American companies to compete internationally.

Jackson played a significant role in pushing for a delay in the Keystone XL Pipeline and led the EPA to set new fuel-efficiency standards for American vehicles as well as new rules for power plants.

Under Jackson, the EPA added increases to Corporate Average Fuel Economy standards which require cars and light trucks to reach 34.5 mpg by 2016, and 54.5 mpg by 2025.

Last week, the EPA finalized changes to the Clean Air Act standards for boilers and incinerators and also updated its national air quality standards for fine particle pollution.

Click here to read the entire article.

Photo of EPA Administrator Lisa Jackson: AP Images