HRA assisted the Bureau of Reclamation with construction of a new irrigation outfall from the Columbia Basin Irrigation Project in Pasco, Washington. HRA provided archaeological monitors at a ¼-mile segment of the outfall pipe right-of-way where it enters the Columbia River, which is located within a previously recorded archaeological site. HRA sampled within an area designated an Archaeological Inspection Trench without finding cultural material, but several archaeological shell midden, hearth, and living floor features, likely a pithouse, were observed when construction excavation expanded to the broader water pipeline trench. In each case, HRA verified that the features were intact and provided additional information on their potential significance and integrity, and this led to emergency data recovery excavations at three locations within the right-of-way and a determination that the pithouse could be protected in place and avoided by further trench excavation. The archaeological excavations revealed additional features, including a likely storage pit, representing two components with the older one dating to more than 5,000 years ago. In total, HRA collected 2,704 pieces of debitage, 55 formed artifacts (tools), 117 pieces of fire-modified rock (FMR), 14 pieces of ochre, 1,339 faunal specimens, and tens of thousands of freshwater mussel shell from 12 excavation units. Throughout the project, HRA subcontracted with the Yakama Nation and Umatilla and Colville Tribes to ensure that tribal monitors could observe the work.