The Types of Soils on Your Lake Bottom

(What is all that icky stuff I’m wading in?)

All lakes are temporary, viewed in geologic time scales. They will fill in over time, eventually becoming wetlands and finally dry land. It is the destiny of lakes to become good farmland. This process cannot be stopped.

Not to worry though, millions of new lakes will be formed when the next glacier comes and goes. That will be approximately 50,000 years from now, give or take a few years. So, until that time, you’d probably like to do something about that yucky, mushy lake bottom.

Here are a few terms that get used interchangeably to describe lake bottom soils...

Sediment is any naturally occurring material that is broken down by weathering and erosion and is moved around by water, wind and ice. Gravity moves sediment to the nearest low spot — your lake!

Silt is granular soil of a size between sand and clay, eroded from other soils and rock. Silt occurs on land as a soil or as suspended sediment in water or settles on the lake bottom. Some of that gooey stuff on your lake bottom used to be majestic rocky cliffs and white, beach sand.

Marl is an old term referring to a variety of soils that occur as loose deposits consisting mostly of a mixture of clay and calcium carbonate, (yes, the same stuff that’s in some antacids) formed under freshwater conditions. Marl is that thick, slippery clay-like soil that’s found beneath mucky sediment.

Mud is just a catch-all term form any type combination of wet soils.

Muck is a soil made up primarily of humus. (Not to be confused with “hummus” the stuff you eat).  Humus refers to any organic matter (like decayed lake weeds) that has reached a point where it can break down no further and can remain essentially as it is for centuries, if not millennia. And that’s a lot of muck.

Consider how “muck” is created:

Lake weeds killed with herbicides decay and make more muck.

• Each fall, as lake all the lake weeds die off, they decay and make more muck.
• Every year when trees leaves blow into the water they decay and make more muck.
• Dust and silt blow into the water everyday and make more muck.
• Everyday, all the creatures in the water relieve themselves and make more muck.
• Waterfowl and other birds relieve themselves everyday and make more muck.
• Everyday, shorelines erode a little and makes more muck.
• Farm runoff makes more muck.
• Agricultural and lawn fertilizers run off make more muck.
• Occasionally, bad septic systems make more muck.

As you can see, there’s not much we can do to stop the natural progression of muck buildup. But what we can do is walk over the top of it on a MuckMat®!