Bacteria and soil.
Bacteria are microscopic bugs. While many types of bacteria are actually good for you, a few can make you sick.
Bacteria are found in many waterways. That’s why you shouldn’t drink straight from a river or lake. These critters can get into rivers from all sorts of places, but a major source is manure from deer, geese, cows, pigs, and other animals.
Also, soil can pollute rivers when it erodes (moves) off of the land and into the water. Soil is one of the most important things on earth because it’s needed for much of the food we eat. But when soil washes into water, it can no longer be used for growing crops. Instead, it causes big problems for fish and boats.
According to the U.S. Environmental Protection Agency, about 13 percent of all river and stream miles are damaged by bacteria. About 12 percent are damaged by eroding soil.
Sediment, or soil, turns a lake muddy. Sediment is the second most common type of pollution in U.S. rivers.
Photo: USDA NRCS