Superfund: Contaminated Sediments

Sediments are materials found at the bottom of a water body. Sediments may include clay, silt, sand, gravel, decaying organic matter, and shells.

Contaminated sediments present risk to human health and the environment and limit the uses of many water bodies. They are often a contributing factor to fish-consumption advisories.

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.
   
• Air pollution can deposit substances such as mercury into sediments.
   
• Contaminated groundwater can discharge through sediments to the overlying surface water.

EPA uses Superfund, in collaboration with other EPA programs, to clean up sediment sites that present an unacceptable risk to human health and the environment.