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MIAMI RIVER COMMISSION c/o Rosenstiel School 4600 Rickenbacker Cswy Miami, Fl. 33149 305-361-4850 Fax: 305-361-4755 e-mail: miamiriver@bellsouth.net This site prepared and designed by Mark Sell Communications, Inc. Public Relations	DREDGING Dredging FAQs:		MORE Historical Overview Dredging Benefits

	What types of polllutants are in the sediments? Are all of the sediments polluted?	The most common types of pollutants in Miami River sediments are heavy metals, such as lead, copper, zinc, cadmium, and mercury. These metals concentrations are ten to one hundred times above what would be expected for natural sediments. They also contain trace amounts of petroleum-related compounds and some types of pesticides. Contamination occurs throughout the navigable section of the River, however the highest concentrations are from Wagner Creek to the mouth of the River. Contaminants are associated primarily with the fine-grained silt and mud which has accumulated in the channel.

	Is the sediment considered "hazardous waste"?	No. "Hazardous waste" is a designation under state and federal law pertaining to substances that could pose a significant threat to human health or the environment if the substance is disposed of, treated or handled improperly. Although the sediments are contaminated, they do not have high levels of pollutants or other properties that pose a significant threat to human health as defined by "hazardous waste".

	If it isn't "hazardous", then why is there a concern about the pollutants?	Federal and State agencies have conducted laboratory experiments, called "bioassays," to evaluate the biological effects of the sediment on marine life. These studies have shown that the sediments from the Miami River are toxic to a variety of marine animals, including crustaceans, worms, clams, small fish, and larval oysters and sea urchins. Over the years, many different studies using a variety of different animals and test procedures have been completed. In these studies, the Miami River sediments have caused mortality, reduced reproduction or growth, or accumulation of contaminants in the test animals. This finding means that the pollution in the sediment could be affecting marine life in the River, and that sensitive wildlife and fisheries resources in Biscayne Bay could be affected if additional polluted sediment is discharged into the Bay.

	Who conducted the sediment tests?	Sediment analyses and bioassays were performed as part of dredging-related and regional studies done by State and Federal agencies. The Florida Department of Environmental Protection, the National Oceanic and Atmospheric Association (NOAA), and the U.S. Army Corps of Engineers from the 1980's through the 1990's performed the most significant work

	Which pollutant causes the toxicity?	The concentrations of the metals, as well as the petroleum-based substances, exceed levels believed to cause biological effects. The toxicity is probably the combined result of several of the pollutants.
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