Clarity

Torch Lake is known for its clear turquoise water. You can see more than 30 feet down into the water.

Key Facts

  • Clarity is a measure of the depth that sunlight penetrates into the water. The ore clear the water, the farther down you can see.
  • Clear water is considered an indicator of clean water.
  • The colors of Torch Lake are related to its clarity.

 

Did you know?

Water Clarity

Particles floating in water decrease clarity.

Particles can come from soil erosion, stormwater run‐off, algal blooms or bottom sediments stirred up by boats and storms.

Clarity is measured with a secchi disk, which looks like a plate with a black and white pie design.

When you lower the secchi disk on a rope into the lake, you can measure the distance from the surface of the water to the depth where it can no longer be seen by the naked eye.

Clarity can be changed by invasive species such as the zebra mussel. These non-native mussels filter more particles out of the water than native mussels. This enables the sunlight to reach farther down in the water, which causes the water to be warmer and reduces the amount of food available for fish. So, the fish population decreases.

Weather can also change clarity. When storms stir up bottom sediments, clarity decreases.

Image source: Minnesota Pollution Control Agency

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You Care

We know you want to enjoy the lake for many years (and generations) to come. So, we’ve put together a list of simple steps you can take to reduce the nutrients, sediments and toxins flowing into the lake and its streams.

Restore the shore.

Let your shoreline go natural. The deep, root systems of trees and shrubs prevent the shore from eroding and bringing sediment into the water.

Eliminate invasive species.

Before putting your boat in the lake, wash your boat and trailer with hot water to remove invasive plants and animals.

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