Why is the water green at Niagara Falls?

Short answer: It's not actually green—it's a mix of blue-green from dissolved minerals and the way sunlight hits the water. The Niagara River carries about 60 tons of dissolved minerals per minute, mostly limestone and shale particles. That gives the water a milky, emerald tint, especially on sunny days. The color changes with weather, season, and water volume, so don't expect it to look like a postcard every time.

If you're seeing a really vivid green, it's usually in the summer when algae blooms kick in, or after a heavy rain when the river churns up more sediment. The water is actually clearer in winter when the flow slows down. But no, it's not dyed or anything weird—just nature doing its thing. If you want the best color, go on a bright, sunny afternoon in late spring or early fall.