What's in the water? Lake Ontario turns neon blue

Thursday, September 19, 2013, 9:20 AM -

Lake Ontario is looking very different these days. 

Photos taken by NASA's Earth Observatory show the lake as a neon blue-green colour, strikingly different than it's usual dark blue. 

Initially this colour change was thought to be caused by a massive algae bloom, raising great concern. Algae is known to produce toxins and cut off oxygen in the water.

Turns out however, that the bluish-green hue was caused by a very common process called "whiting." 

"Whiting is a late summer event common in lakes that have a lot of calcium carbonate in the water," says Jim Watkins, Post Doctoral Researcher at Cornell University in New York. "At the end of the summer these crystals form a solution, which forms a kind of milky colour which reflects a lot of light and actually creates a neon blue colour."

(NASA)

Lake Ontario has a limestone basin, primarily made up of Calcium Carbonate.

When temperatures go up, it changes the water's PH level, which leads the mineral to precipitate out into fine particles that linger in the water column. 

Typically its milky effects last four to six weeks, then its back to its usual blue in early October. 

Unlike algae, whiting poses no real threat to humans or life in the water.