The John Day Turbine Replacement and Generator Rewind Project is a significant undertaking by the U.S. Army Corps of Engineers (USACE) to replace 16 turbines within the John Day Lock and Dam on the Columbia River. Planning for this project originated with the Columbia River System of Operations (CRSO) Environmental Impact Statement (EIS), which broadly identified maintenance and operations improvement alternatives for the larger system of 14 USACE-operated projects in the Columbia River System. Pinyon developed an Environmental Assessment (EA) that tiered off the CRSO EIS to provide a specific, local assessment of the environmental effects for the turbine replacements. Development of the EA included a heavy focus on aquatic habitat, fish survivability, and hydrology, along with evaluation and consideration of regional tribal interests in fishing along the Columbia River.