Occasionally, a season comes along that allows the growth of a bacterium native to Wisconsin soils. This anaerobic bacterium needs a little warmth, moisture and no oxygen to grow. If the ice is thin over an area of soil that has the bacterium, and the sun warms the ground under the ice, thus cutting off the oxygen - these conditions may allow the bacterium to grow. As it grows, it produces its own heat making the ice above soft. It starts to bulge the ice upward, have a brownish tint to it and it stinks. The bulges expand causing bumps we can’t fix. Although harmless to humans and clothing, the bacterium stinks. This is thanks to Mother Nature again. We have found that if it is really cold early and for a long time during our initial buildup, the ice gets thick enough and does not allow the sun to warm the soil beneath the ice. Thicker ice usually means less bacterial growth.