The Hidden Cost of Hydropower: 7 Alarming Ecological Impacts

Dams generate clean electricity — but at a steep ecological price. Here's what America's rivers pay for that power.

Dams Block Salmon Runs — A Pacific Northwest Crisis

Salmon need unobstructed rivers to spawn. The Snake River dams alone have driven wild salmon populations to near-collapse, threatening indigenous livelihoods and ecosystem health.

Sediment feeds deltas, beaches, and floodplains. Without it, coastlines erode and river ecosystems starve of nutrients vital to aquatic life.

Reservoirs Release Cold Bottom Water — Shocking Native Species

Cold water released from dam depths disrupts the natural seasonal temperature cycle, killing warm-water fish species adapted to natural river rhythms downstream.

"Green" Hydro Emits Methane From Rotting Vegetation

Reservoirs flood forests and grasslands. Decomposing organic matter releases methane — a greenhouse gas 80× more potent than CO₂ — making some dams net climate emitters.

Habitat Loss, Invasive Species & Tribal Water Rights

Reservoirs flood riparian habitat (5), create warm stagnant conditions that favor invasive species like quagga mussels (6), and violate indigenous communities' treaty water rights across the West (7).

Dam Removal is Restoring American Rivers

Over 2,000 US dams have been removed. The Elwha River restoration — removing two dams in Washington — brought salmon back within years. River recovery is possible.