To build the main dams at Muskrat Falls, the river was diverted through the spillway in summer 2016.
The spillway has five bays with gates that open and close as needed to control the release of water from the reservoir.
Cofferdams will be built upstream and downstream of the North Dam construction site to create a dry environment to build the North Dam. The upstream cofferdam will be used to divert the river through the spillway.
In fall 2016, when the cofferdam is in place, water levels in the lower Churchill River valley (upstream of Muskrat Falls) will be increased to an initial elevation of 25 m. This will be the first phase of creating the Muskrat Falls reservoir.