Hydroelectricity works by letting water flow from a higher point to a lower one through a turbine, which spins a generator to make electricity. Canada has enormous rivers, lots of elevation change and a long history of building dams, so hydro supplies more than half of the country's electricity, about 55% in 2025 according to Statistics Canada. That's why grids in Quebec, Manitoba, British Columbia, Newfoundland and Labrador and Yukon are among the cleanest in the world.
Key takeaways
- Hydro turns the energy of falling or flowing water into electricity, with very high efficiency (often around 90% at the turbine).
- Canada is one of the world's largest hydroelectricity producers, and hydro made up about 55% of national generation in 2025.
- Reservoir dams can store energy and ramp up or down quickly, making hydro an ideal partner for wind and solar.
- Drought since 2023 has noticeably lowered Canadian hydro output, pushing the share to its lowest level in a decade.
- New large dams have major environmental and social impacts, especially on Indigenous communities, which shapes how and whether they're built.
How a hydro plant makes electricity
- Water is held back behind a dam in a reservoir, or diverted from a river.
- Gravity pulls it down through a large pipe called a penstock.
- The water spins a turbine. The higher the drop (called "head") and the more water flowing, the more power.
- The turbine turns a generator, where magnets and copper coils produce electricity.
- Transformers step up the voltage and transmission lines carry power to cities, sometimes over a thousand kilometres away.
- Water returns to the river downstream.
Unlike burning fuel, no combustion is involved, so operating emissions are very low. Our main hydro page has diagrams and more detail.
Types of hydro
| Type | How it works | Strengths | Trade-offs |
|---|---|---|---|
| Reservoir (storage) | A dam stores large volumes of water | Stores energy; flexible output; very large scale | Floods land; changes river ecosystems |
| Run-of-river | Uses natural river flow with little or no storage | Smaller footprint | Output follows river flow and seasons |
| Pumped storage | Pumps water uphill when power is cheap, releases it when needed | Acts like a giant battery | Uses more energy than it returns; needs suitable geography |
| Small hydro | Plants under roughly 50 MW, often run-of-river | Can serve remote and Indigenous communities | Site-specific; limited output |
Why Canada runs on hydro
Geography
Canada has vast rivers flowing from high plateaus and mountains to the sea, plus abundant rain and snowmelt. The Canadian Shield, the Rockies and Labrador's plateaus create the drops hydro needs.
History
Provinces built publicly owned utilities in the 20th century and invested in massive projects, including Quebec's James Bay complex, Labrador's Churchill Falls, Manitoba's Nelson River stations and BC's Peace and Columbia river dams.
Provincial differences
| Province or territory | Role of hydro |
|---|---|
| Quebec | The vast majority of generation; major exporter |
| Manitoba | The vast majority; exports to neighbours |
| British Columbia | The large majority; Site C reached full operation in 2025 |
| Newfoundland and Labrador | The large majority, including Churchill Falls and Muskrat Falls |
| Yukon | The majority of grid power |
| Ontario | A significant share alongside nuclear |
| Alberta, Saskatchewan, Nova Scotia | Smaller shares in grids still using fossil fuels |
See your own grid on our provinces page, or jump to the Quebec and Manitoba guides.
Hydro as the grid's "battery"
Reservoir hydro is incredibly flexible. Operators can open or close gates in minutes, so hydro can:
- Follow daily swings in demand.
- Fill in when the wind drops or the sun sets.
- Store water when wind and solar are plentiful, saving it for later.
That's why provinces with large hydro systems are well placed to add wind and solar. Wind's variability (see capacity factor explained) matters less when a reservoir can balance it.
Drought and a changing climate
Hydro depends on precipitation. Persistent drought since 2023 has lowered reservoir levels in several provinces. Statistics Canada reported that hydro generation in 2024 hit a record low for its current data series, with 2025 only slightly higher, and hydro's share fell to about 55% of national generation in 2025. Lower hydro output reduced exports and increased imports, and Canada was even a net electricity importer in some months.
Climate change is expected to shift precipitation patterns, with some regions getting wetter and others drier, and more variability overall. Diversifying with wind, solar and storage helps make hydro-based grids more resilient. Read more on our future of energy page.
Environmental and social impacts
Hydro is low-carbon, but not impact-free:
- Flooding land for reservoirs can destroy habitat, forests and farmland.
- Methylmercury can rise in new reservoirs as flooded vegetation decomposes, affecting fish and people who rely on them.
- Fish passage and river flows change downstream.
- Reservoir emissions from decomposing vegetation can be significant in early years, then decline.
- Indigenous rights and communities: many large projects flooded traditional lands and disrupted ways of life. Modern projects increasingly involve consent, partnership and ownership, though histories remain painful.
Frequently asked questions
Is hydroelectricity renewable?
Yes. It relies on the water cycle, powered by the sun. Its lifecycle emissions are generally very low compared to fossil fuels, though they vary by reservoir.
Can I install hydro power at home?
If you have a stream with enough drop and flow, micro-hydro systems can provide steady power, often more consistently than solar or wind. Permits for water use are required, so check with your province first.
How long do hydro dams last?
Many operate for 100 years or more with upgrades. Turbines and generators are refurbished periodically, sometimes increasing output.
The bottom line
Hydroelectricity is simple in principle, falling water spinning a turbine, and it's the backbone of Canada's clean electricity. Its flexibility makes it the ideal partner for wind and solar, while recent droughts show why diversity matters. Understanding hydro helps explain why some provinces already have very clean grids and how others can get there. Explore related terms in our glossary.
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