HRA assisted the Washington State Department of Transportation (WSDOT) with public involvement, National Environmental Policy Act/State Environmental Policy Act documentation, and cultural resources inventory and assessment for the U.S. Highway 12 Four-Lane Project between Wallula and Walla Walla. HRA assisted WSDOT in defining the area of potential effects for several alternatives, participated in Tribal consultations, and conducted background research and field investigations of the 1,500-acre project area. HRA staff analyzed the results and recommended National Register of Historic Places-eligibility determinations and mitigation measures for significant resources in support of WSDOT’s Section 106 of the National Historic Preservation Act compliance requirements. HRA staff also drafted a construction monitoring plan that ensured avoidance of several historic properties, including Wallula, an important traditional heritage resource of the Confederated Tribes of the Umatilla Indian Reservation.