Tanya Lewis, chairwoman for the Yavapai-Apache Nation in Arizona, left, and Col. Andrew Baker, commander of the U.S. Army Corps of Engineers Los Angeles District, right, sign a project agreement Dec. 16 for design and construction assistance for the Yavapai-Apache Nation Wastewater Treatment Plant in Arizona. The project aims at providing a sustainable treatment method that will improve overall health, sanitation and security for the Nation, the environment and all communities that rely on the Verde River.