Washington state regulators on Tuesday completed the initial steps toward establishing rules that would prohibit the use of fossil fuels in producing electricity.

In a state where nearly 70% of the power already comes from hydro-electric sources, the Washington Utilities and Transportation Commission (WUTC) is finalizing a work plan toward implementing state Senate Bill 5116, the Clean Energy Transformation Act (CETA) and related bills.

In May, Gov. Jay Inslee signed into law a bill requiring 100% alternative energy by 2045.

“We are committed to carrying out the requirements of CETA and reaching the goal of 100% clean energy in Washington,” said WUTC Chair David Danner. “It’s complicated but absolutely achievable. Now we’re rolling up our sleeves and getting to work.”

Still to be completed are specifics in individual rulemakings, which WUTC spokesperson Kate Griffith said should “engage stakeholders on what investor-owned utilities will need to do to comply with the new laws.” The next round of integrated resource planning should shed more light on future needs.

“The commission’s final plan released Tuesday incorporates many changes suggested by the public, and continued public input throughout implementation will be a key component of implementing CETA and related legislation over the next three years,” she said.

The most recent data from the state Department of Commerce identified nearly 68% of the state’s electricity from hydroelectric sources, 13% from coal, nearly 11% from natural gas and less than 3% from wind and solar. A total of 77.6 Bcf of gas was used for power generation in 2017 in Washington, or 38% of its overall gas consumption.