Sediment
What is the Sediment?
Sediment is the loose sand, clay, silt and other soil particles that settle at the bottom of a body of water. Sediment can come from soil erosion or from the decomposition of plants and animals. Wind, water and ice help carry these particles to rivers, lakes and streams.
Contaminated sediments present risk to human health and the environment and limit the uses of many water bodies. Sediments can become contaminated in a number of ways:
- Urban runoff that discharges to surface waters often contains oil, grease, heavy metals and other harmful substances.
- Agricultural runoff may contain nutrients and pesticides.
- Industrial spills and releases, especially those that occurred before controls were in place, can put damaging products into the water.
- Airborne contaminants may also be deposited in sediments, such as mercury.
- Contaminated groundwater can discharge through sediments to the overlying surface water.