On March 31, 2004, Washington Governor Gary Locke signed into law a bill that requires new fossil fueled power plants in the state to offset 20 percent of their CO2 emissions. All new fossil fueled electric generating facilities over 25 MW are covered by the legislation, as are existing facilities that seek to make modifications that would increase CO2 emissions by 15 percent or more. Affected parties may invest directly in CO2 mitigation projects, or they may pay an approved third party to conduct the mitigation at a rate per ton specified by the state Energy Council. The affected facilities also may meet some or all of their offset requirements through direct application of combined heat and power. The Washington requirement is modeled after one adopted by Oregon in 1997, which requires CO2 offsets of 17 percent.