Grand Falls-Windsor Dam Project

grand-falls-damHydro will be undertaking extensive rehabilitation work to modernise the dam at the hydroelectric plant in Grand Falls-Windsor over a three year period, starting October 2016.

The primary work includes  the reinforcement of the existing concrete structure and the installation of a new inflatable spillway over the dam’s crest. This work will stabilize the dam, allow greater control for spilling, better assist fish passage, and make ongoing maintenance activities much safer.

The generation facility at Grand Falls-Windsor is the largest of three hydroelectric facilities on the Exploits system and has an electrical generating capacity of 75 MW for the island grid. The main purpose of the dam is to divert water to the power canal.

Upgrading the dam is essential in terms of ensuring generation supply and reliable service for customers.

New Inflatable Spillway

The dam, which extends across the Exploits River, currently uses timber flashboards to increase pond elevation for additional generation and fish passage. These flashboards need to be replaced often and it is challenging and dangerous work.

The inflatable overflow spillway – the first of its kind in the province – will replace the flashboards and allows greater spill capacity/control. It is designed to improve the ability to adjust water flows and levels for power production, fish passage and safety reasons.

The inflatable portion of the dam will be installed in three sections which can control flows independently along the dam – this will make it easier to control ice and other debris which could impact power generation.

Other Work

The project will also include the creation of a single lane vehicle bridge and a pedestrian bridge to provide safe access during construction and future maintenance activities.


Construction activities are planned to be completed in various phases over a three year period during which the Grand Falls generating facility and dam will continue to function as per its current operating and water management practices.

Atlantic Salmon Run

Hydro is an active steward in the development of the Atlantic salmon run on the Exploits River. Migration patterns will not be hampered by construction activities.