EPA Administrator Lisa Jackson announced her plans to leave her post after President Obama's inauguration. During her time in the role, she drew fire from the coal industry and manufacturers for her work to increase scrutiny of mountaintop removal coal mining and tighten regulations on coal-fired power plants. But she also won support from environmental groups and occasionally grudging respect from her opponents.Her successor is unknown, but reports are speculating it could be either Deputy Administrator Robert Perciasepe or Assistant Administrator for Air Gina McCarthy.Twitter reaction to the announcement ranged from an enthusiastic "the witch is gone!" from @VoteCoal, to praise for Jackson's work pushing through landmark air pollution regulations from groups like the Sierra Club and Moms Clean Air Force.Here's a roundup of news and reaction to the announcement from the Twittersphere: [View the story "Twitter reaction to EPA chief's resignation" on Storify]