How hydro works, why Canada is a hydro superpower, its real impacts and partnerships, micro-hydro for rural land, and hydro's role in net zero.
When you flip a light switch in Quebec, Manitoba, British Columbia or Newfoundland and Labrador, the power almost certainly comes from falling water. Hydroelectricity is the backbone of Canada's electricity system, supplying more than half of the country's power in a typical year. Yet most people know surprisingly little about how it works, what it costs, or who has lived with its consequences.
This course gives you the full picture in plain language. You'll learn how hydro stations turn water into electricity, the three main types of hydro, why Canada's geography makes it a hydro superpower, and how hydro shapes provincial grids and electricity bills. We look honestly at the environmental effects of dams and reservoirs and at the history of hydro development on Indigenous lands, including today's move toward Indigenous partnership and ownership. Finally, we cover micro-hydro for rural properties and hydro's growing role in balancing wind and solar on the road to net zero.
Sundamentals is an independent non-profit. We don't sell energy systems or take commissions, and we don't represent any utility or developer. Our aim is to help you understand the energy choices facing your household, your community and your province.
The course is free, self-paced and takes about 50 minutes. It has three modules with short knowledge checks and a 10-question final exam. Score 80% or higher on the exam to download your PDF certificate of completion.
Hydroelectricity captures the energy of water as it moves downhill. The sun evaporates water from oceans and lakes, and it falls again as rain and snow, much of it on higher ground. As that water flows back toward the sea, it carries energy that a hydro station can turn into electricity. In a sense, hydro is solar energy delivered by the water cycle.
At a typical station, water enters an intake protected by screens and travels down a large pipe or tunnel called a penstock. The rushing water spins a turbine, which is connected by a shaft to a generator. Inside the generator, magnets turn past coils of copper wire, producing alternating current electricity. The water then flows out through a channel called a tailrace and back into the river, and transformers raise the voltage so the power can travel long distances on transmission lines.
Two things decide how much power a site can make: head and flow. Head is the vertical distance the water falls. Flow is the volume of water passing through each second. Double either one and you roughly double the power. A mountain stream can have a lot of head but little flow, while a big river like the St. Lawrence has modest head but an enormous flow. Different turbine designs suit different sites, from bucket-wheel Pelton turbines for high heads to propeller-style Kaplan turbines for low heads.
Hydro is remarkably efficient and long-lived. Large modern turbines and generators can convert around 90% of the water's available energy into electricity, far more than any fuel-burning power plant. Some Canadian stations have been running, with upgrades, for close to a century.
It also helps to separate capacity from energy. Capacity, measured in megawatts, is how much power a station can produce at once. Energy, measured in megawatt-hours, is how much it actually produces over time, and that depends on how much water arrives in a given year. In a dry year, even the biggest station produces less.
Reservoir hydro, sometimes called storage hydro, uses a dam to hold back a large lake. The reservoir stores spring snowmelt and rain so it can be used months later, including through the long Canadian winter. Operators can open or close the gates within minutes, so a reservoir station can follow demand up and down. Canada's largest hydro systems, such as the La Grande complex in northern Quebec, the W.A.C. Bennett Dam on BC's Peace River and Churchill Falls in Labrador, are built around huge reservoirs.
Run-of-river hydro uses a river's natural flow with little or no storage. Some stations divert part of a stream through a pipe and return it downstream; others sit on large rivers with a steady flow. Because there is little or no reservoir, run-of-river projects usually flood much less land, but their output rises and falls with the river: high during the spring freshet, lower in late summer and in the depths of winter. They can still affect fish and stream flows, so careful design and monitoring matter. Many smaller run-of-river projects operate in British Columbia.
Pumped storage works like a giant rechargeable battery. It uses two reservoirs at different heights. When electricity is plentiful and cheap, for example on a windy night, pumps move water to the upper reservoir. When power is needed, the water flows back down through turbines. Some energy is lost along the way, typically around 20% to 30%, so pumped storage is a way to store electricity rather than a source of it. It is the largest form of grid energy storage in the world today.
Canada has relatively little pumped storage so far, because its big reservoirs already provide so much flexibility. Ontario operates a pumped storage station at Niagara, and larger new proposals in Ontario and Alberta are in planning and assessment stages. As wind and solar grow, interest in pumped storage is rising.
Canada's geography is almost purpose-built for hydro. The country is vast, receives plenty of rain and snow, and is crossed by large rivers that drop from mountains, plateaus and the rocky Canadian Shield on their way to the sea. Countless lakes provide natural storage. Few countries combine so much water with so much elevation.
Hydro is the single largest source of Canada's electricity. In wetter years it has supplied around 60% of the country's power. In recent dry years the share has dipped: the Canada Energy Regulator reports about 58% in 2023, and Statistics Canada reports about 55% in 2024, when drought cut output in Quebec and Manitoba. Canada also ranks among the world's largest hydro producers, alongside China, Brazil and the United States.
Much of today's system was built in waves. Early stations at places like Niagara Falls and Shawinigan powered growing cities and industries in the early 1900s. After the Second World War, provinces built massive projects: the Manicouagan and James Bay developments in Quebec, the Peace and Columbia River projects in BC, Churchill Falls in Labrador, and the Nelson River stations in northern Manitoba.
Building continues, though more slowly. Keeyask in Manitoba was completed in 2022 as a partnership with four Cree Nations. Muskrat Falls in Labrador is operating after major cost overruns. BC Hydro's Site C, at roughly 1,100 megawatts, reached full operation in 2025. In August 2026, Newfoundland and Labrador, Quebec and the federal government announced a new agreement to replace the 1969 Churchill Falls contract and pursue a new Gull Island station, with final binding agreements still to be completed.
Hydro also makes Canada a major electricity exporter. Hydro-Québec's power now flows to New York City through the Champlain Hudson Power Express line, which began commercial operation in May 2026. Exports depend on the weather, though: in dry years, Canada exports less and imports more.
Electricity in Canada is mostly managed province by province, and each grid reflects its local resources. In Quebec, Manitoba, British Columbia and Newfoundland and Labrador, hydro typically supplies around 90% or more of electricity generation. Ontario relies mainly on nuclear, with hydro supplying roughly a quarter, plus natural gas, wind and solar. Alberta and Saskatchewan have few good hydro sites and depend mostly on fossil fuels, with growing wind and solar.
That mix shows up on your bill. Hydro-heavy provinces have some of the lowest residential electricity rates in North America. Many of their big dams were built decades ago and are largely paid off, hydro burns no fuel, and stations can run for a century with upgrades. Publicly owned utilities in these provinces generally set rates under regulatory oversight, passing on those low costs.
New hydro is a different story. Large projects take a decade or more to plan and build and can face major cost overruns. Site C's budget grew to around 16 billion dollars, and Muskrat Falls cost far more than first estimated, which raised concerns about rate increases in Newfoundland and Labrador and led to rate-mitigation efforts. Today's ratepayers benefit from yesterday's dams; tomorrow's projects need careful scrutiny.
Hydro-heavy grids are also among the cleanest in the world. That means switching to a heat pump or an electric vehicle in those provinces cuts emissions dramatically, a topic covered in our heat pump and EV courses.
Finally, hydro depends on the weather. Drought means less water, so utilities may import more power, sometimes generated from fossil fuels, and pay more for it. Climate change may shift when and how much precipitation falls, which is why utilities are studying long-term water supply carefully.
Hydro produces very low emissions once it is running, but it is not impact-free. Large reservoirs flood forests, wetlands, hunting grounds and trap lines. Flooded vegetation decomposes and releases greenhouse gases, mostly in the first years after flooding. Flooding can also release naturally occurring mercury from soils, which bacteria convert into methylmercury that builds up in fish. This has led to fish consumption advisories that can last for many years.
Dams change rivers too. They can block fish migration, alter water temperatures, trap sediment and change the timing of downstream flows. Fish passages, minimum flow rules and protections under the federal Fisheries Act aim to reduce these harms, but they cannot eliminate them.
Many of Canada's largest projects were built on Indigenous lands with little or no consultation, let alone consent. Communities saw homes, burial sites and traditional territories flooded, and some were relocated. In northern Manitoba, Cree communities lived with the effects of river diversions for decades. In Quebec, Cree and Inuit opposition to the James Bay project led to the 1975 James Bay and Northern Quebec Agreement, often called Canada's first modern treaty, and later to the 2002 Paix des Braves agreement. Site C faced long-running opposition and legal challenges from some Treaty 8 First Nations.
Today the approach is changing. The Crown has a legal duty to consult, and governments have committed to implementing the United Nations Declaration on the Rights of Indigenous Peoples. More projects are now built as partnerships, with Indigenous nations as owners who share in revenues, as with Keeyask in Manitoba and many smaller run-of-river projects in BC. Partnerships do not erase past harms, and every community's experience is different. The best guide is to listen to the communities most affected.
Micro-hydro refers to small systems, usually up to about 100 kilowatts, and home systems are often just a few kilowatts or less. Their big advantage over solar and wind is that they can run 24 hours a day whenever the water is flowing. A turbine producing just one kilowatt continuously makes about 24 kilowatt-hours a day, which is a meaningful share of a typical home's daily use.
A good site needs both head and flow. A rough rule for estimating output is: power in kilowatts equals 9.81 times the head in metres, times the flow in cubic metres per second, times the system efficiency, often around 50% to 70% for small systems. For example, a stream with 20 metres of head and 20 litres per second of flow could produce a little over 2 kilowatts, or roughly 55 kilowatt-hours a day. What matters most is reliable flow through the driest part of late summer and the coldest part of winter, so measure your stream across the seasons before you buy anything.
A typical system has a screened intake, a pipe running downhill, a turbine and generator, and a controller that sends any surplus power to a dump load such as a water heater. Off-grid systems usually add batteries and an inverter. Long wire runs between the turbine and the house waste power, so distance matters.
Water in Canada is publicly owned, so you will usually need a water licence or approval from your province, and fish habitat is protected under the federal Fisheries Act. Grid-connected systems must also follow your utility's interconnection rules. Talk to your provincial regulator early.
Micro-hydro makes the most sense on hilly, off-grid or remote properties with a year-round stream, especially where diesel or long power lines are the alternative. It often pairs well with solar, since streams tend to run strongest when sunlight is weakest. It rarely makes sense on flat land, with seasonal creeks, or where cheap grid power is already available.
Canada has legislated a goal of net-zero emissions by 2050 under the Canadian Net-Zero Emissions Accountability Act. Getting there means electrifying much of our heating and transportation, and many analyses, including the Canada Energy Regulator's net-zero scenarios, suggest Canada could need roughly twice as much electricity by 2050. Much of that new supply is expected to come from wind and solar, which are now among the cheapest sources of new power but vary with the weather.
This is where hydro reservoirs shine. When the wind is blowing and the sun is out, hydro operators can hold water back in their reservoirs. When the wind drops or the sun sets, they can release it and ramp up quickly. In effect, a large reservoir works like an enormous battery that can store energy for days, weeks or even seasons, something batteries cannot yet do economically at that scale.
Transmission links multiply that value. Hydro provinces already trade power with neighbours, and stronger connections between provinces, such as linking BC's hydro to Alberta's growing wind and solar, could let regions share their strengths. Upgrading existing stations with new turbines and generators, adding pumped storage, and building new projects as true partnerships with Indigenous nations are all part of the picture.
Hydro has limits. The best large sites are already developed, new dams are costly and contested, and droughts show that water supply can't be taken for granted. That's why hydro works best as a partner to wind, solar, storage and efficiency rather than a solution on its own.
For households, hydro's clean, flexible power is a big reason heat pumps and electric vehicles cut emissions so effectively in many provinces. Understanding your province's grid helps you make the most of it.
Next step: Explore hydro energy →
