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Cascade River State Park

Root Beer Water

Have you ever been exploring the North Shore and come across a river or a body of water that looks similar to root beer? This is not uncommon here! Most people think root beer water caused by water containing large amounts of silt, or the result of mud from the bottom of the river.  Neither of these is actually the cause of Root Beer Water, however.

The Real Cause

Turns out, the amber-brown color of the water comes from tannins.  Tannins are the bitter and astringent compounds that come from the wood, bark, and leaves of oak and fruit trees in the area. When root beer water appears, it typically means the river has flowed through a swamp area. This is due to swamp areas having an abundance of tannins in the water. They get caught in the river flow and head downstream. By the time you see them on the rivers or waterfalls near Lake Superior, the tannins have fully blended in.

Tannins’ purpose in the wild is to give plants and fruits a bitter taste before they become fully ripe.  This deters animals from eating unripened foods. If you are a wine enthusiast, you may also be familiar with tannins as they relate to wine production. They provide taste. texture, and weight to red wines.

One example of where you can often see this weird phenomenon is at Cascade River State Park. With how fast the water rushes down the cascades, it’s hard to believe that it’s really just tannins being carried along!

Root Beer Water in Lake Superior

Lake Superior sometimes seems reddish-brown in color, as well.  This is usually not caused by tannins. Instead, this happens when strong winds or rains launch red clay particles and other sediments into the water. The sediments don’t cause any harm, although we imagine it does give spectators an uneasy feeling.  Most are used to that cool-blue water that the lake is known for.

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