A powerful national environmentalist group is challenging the EPA permit for a large co-generation power plant to be built at Sierra-Pacific's Mill in Anderson. The company was awarded a permit modification in May to start building a much larger biomass co-generation plant than the one currently used at their mill on the Sacramento River next to Interstate Five. The steam is used to dry lumber, with the excess used to generate electricity. Shasta County Department of Resource Management says the new 31-Megawatt biomass-burning plant will be comparable in size to the Wheelabrator Plant on the other side of town. The local group "Citizens For Clean Air" had successfully held up the project through the EPA appeals process, demanding the use of "best available technologies" and questioning the facility's effect on ambient air quality. That group has apparently exhausted their avenues of protest. On Friday, the Center for Biological Diversity, which claims to have more than 775-Thousand members, filed suit against the EPA in the 9th U.S. Circuit Court of Appeals. The suit accuses the EPA of failing to control carbon dioxide pollution, and questions whether the plant should be allowed to burn whole trees rather than just mill waste.