So what causes TDG supersaturation? That's easy, think waterfalls.

When water plunges over a waterfall and into a deep pool, it takes air bubbles with it. The high pressure causes the bubbles to change into a solution. This mixes with the normal water, so now the water is supersaturated with gases, primarily nitrogen (70%). It's kind of like putting the fizz into soda pop.

So if you're looking at a beautiful waterfall, you may be seeing TDG supersaturation happening as a normal part of nature. And if you're looking at water falling over the spillway of a dam, you may be seeing it as part of what humans create.

In the Columbia Basin, there are a lot of dams in both Canada and the United States. As a result, monitoring and finding ways to reduce TDG supersaturation to safe levels is a big deal.