When the EPA announced it will require states to reduce emissions of carbon dioxide to 30 percent below 2005 levels by 2030, it wasn’t applying that exact target to everyone.

In practice, some states will have to lower emissions by more than 30 percent while others will cut below that, but the overall reduction would basically amount to the EPA reduction (see map below). That’s because the agency set up a formula that looks at states' most recent emissions along with other factors such as their ability to shift to natural gas or expected closings of coal plants when setting a 2030 goal.

The agency started with a baseline of 2012 emissions and applied some key assumptions about what each state could reasonably achieve by 2030. The EPA took that 2012 data, assumed basic increases in efficiency, accounted for unused capacity in the less-harmful natural gas sector, estimated how much a state could generate from renewable or nuclear sources and, lastly, forecasted how much a state could decrease demand from users.

That method led to great variation among states, from a 14-percent target in Rhode Island to about 72 percent in Washington state. EPA officials explained in a conference call with reporters that Washington’s target is higher because the state already plans to close a major coal plant in 2020 and the state is aggressively pursuing renewable sources that will likely curb emissions dramatically.

Big coal-producing states such as Kentucky, Wyoming and West Virginia have more modest targets, at 18 percent, 19 percent and about 20 percent respectively. Vermont and Washington, D.C., have no emissions goal because neither has a fossil-fuel-powered plant.

Susan Tierney, an expert on energy policy at the Analysis Group, said that she believed the EPA’s new requirements were and “respectful of existing technology” in each state, and that the methodology to determine how much each state must reduce emissions does not unfairly target states that rely on coal for their current power. “The EPA is not asking a state to go farther than its resources will allow it to go,” Tierney added.

States will have the opportunity to question the targets set by the EPA over the next 120 days and try to amend them before the agency finalizes the rules about a year from now. The rules will likely face legal challenges from states and private companies.

The map below shows the percentage of carbon dioxide (from 2012 levels) each state will have to reduce from its power utilities, with greater reductions shown in red. The cuts are in pounds of carbon dioxide per megawatt hour of electricity generated. For more on the methodology, read the EPA's technical guide. For more on the agency's thinking for each state, see this interactive map.