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River Diversion & Impoundment

Since construction on the Muskrat Falls Project began in 2013, progress on the new 824 megawatt (MW) hydroelectric generating facility has continued. To facilitate construction of the North Dam at Muskrat Falls, the lower Churchill River has been diverted through the spillway and, in fall 2016, the reservoir will be impounded to an initial elevation of 25 m.

Browse through the information below to learn more about river diversion and impoundment at Muskrat Falls.

Construction Activities in 2016

MF Spillway InfographicTo 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.

PrintCofferdams 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.

Change in Water Levels 25mIn 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.

Change in Water Levels 39mWhen the North Dam is complete, water levels in the reservoir will be increased to the maximum height of
39 m.

River Diversion

River diversion is the redirection of the river. To build the North Dam across the main river channel at Muskrat Falls, the lower Churchill River has been redirected through the spillway.

How will the river be diverted?

PrintRiver diversion began by placing rock material across the main river channel to build a cofferdam. This is just upstream of the location where the North Dam will be constructed. This process is called river closure.

During river closure, the spillway bays will open to let water flow through. As rock placement and river closure progress, water flow through the spillway will increase. When rock placement has advanced all the way across the river channel, the river will be completely diverted through the spillway.

River closure will not change the downstream flow or water level from its natural state.

Creating the Muskrat Falls Reservoir (Impoundment)

Reservoir impoundment is the process of increasing the water elevation behind a dam to create a reservoir.

Impoundment of the lower Churchill River to an elevation of 25 m will begin in fall 2016, immediately following completion of the upstream cofferdam.

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It will take approximately two to three weeks to impound the reservoir to the initial elevation of 25 m. The reservoir is expected to rise by approximately 0.5 to 1.0 m/day.

Change in Water Levels 39mDuring impoundment, water flow downstream of the dam will be kept above 30% (552 m3/s) of the historical average flow (1840 m3/s).  After impoundment, water flow downstream of the dam will be the same as the natural flow.

When the North Dam is complete, water levels in the reservoir will be increased to the maximum height of 39 m.

Important Public Safety Information

Stay safe around hydroelectric facilities. Watch for signs and be aware of the hazards.

Important Safety Information

The Muskrat Falls facility will be marked with safety signs. There will also be fences, buoys, booms and barriers to keep you a safe distance away. If you are in the lower Churchill River valley, here’s what you should to do to stay safe:

  • Avoid waterways upstream and downstream of generating facilities, whether open water or ice covered.
  • Obey all danger and warning signs and stay a safe distance from booms and hazard buoys.
  • Stay well back from the edge of a waterway or steep slopes along the reservoir. These areas may be slippery or unstable.
  • Be aware of changing water levels.
  • Never stand, anchor or tie your boat below a dam. Water levels and flows can change rapidly, swamping your boat or putting you in an undertow.
  • Be cautious of dry areas below dams. Water levels can quickly change and exposed sandbars can become submerged.
  • Stay away from generating facility structures.
  • Do not enter secured areas or tamper with equipment.

For more information, read the Important Safety Information sheet.

Keeping Our Facilities Safe

The Muskrat Falls generating facility is being built to the highest standards of dam safety and construction.

As part of our safety program, detailed inspections, monitoring and analysis will be performed throughout the life of the facilities at Muskrat Falls.

Keeping our Facilities Safe Graphic

Regular monitoring will be conducted using:

Keeping our Facilities Safe Table

Stay Informed

Nalcor Energy is committed to providing timely, relevant information to the public about changes to the Churchill River.

During construction at Muskrat Falls, watch and listen for public notices in the local newspaper and on the radio, signs along the river to warn of safety hazards, and safety notices posted on our website and in social media on Twitter and Facebook.

If you have questions or would like more information, contact our team:

E: lowerchurchill@nalcorenergy.com
T: 1-888-576.5454
Project Office: 18-21 Burnwood Drive, Happy Valley-Goose Bay

MUSKRAT FALLS PROJECT