Three generators at the 6.8GW Grand Coulee Dam – the largest hydropower facility in the US – are to be modernized under plans announced by the US Bureau of Reclamation (USBR).

A final Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) has been released for the project, which would replace generating units G-19 through G-21 that have been in service for 30-years and have surpassed their life expectancy. “This modernization project in the Third Power Plant will result in higher efficiency and reliability, ensuring another 40 years of service and enabling Reclamation to meet its contractual obligations for power generation,” said Grand Coulee’s Deputy Power Manager Doug Anderson.

In this EA, the Proposed Action and No Action alternative for any potential environmental impacts were analyzed. The Proposed Action – Third Power Plant Units G19 through G21 modernization with potential for full replacement of major unit systems – was selected. The Proposed Action includes a design-build option for the contractor to provide up to a full component replacement of each generating unit if necessary. Construction work is expected to begin as early as 2023.