Decomposition
The breakdown of complex organic substances into more simple organic chemicals or substances. The ultimate product of decomposition in an aerobic environment is carbon dioxide.

Designated Scientific and Natural Areas SNA
See Scientific and Natural Areas

Designated Uses
The role that a water body is slated to fulfill, such as a drinking water source. Uses are specified in water quality standards for each water body or segment, whether or not the current water quality is high enough to allow the designated use. Other typical uses of a water body include propagation of fish and wildlife, recreation, agriculture, industry, and navigation.

Dichlorodiphenyltrichloroethane DDT
DDT, one of the nine critical pollutants, was commonly used as an insecticide after World War II and is now banned in the U.S. and Canada. DDT and its metabolites are toxic pollutants with long-term persistence in soil and water. They concentrate in the fat of wildlife and humans and may disrupt the human body's chemical system of hormones and enzymes. DDT caused eggshell thinning in a number of fish-eating birds and is associated with the mortality of embryos and sterility in wildlife, especially birds. DDT still enters the Great Lakes, probably from a number of sources including airborne transport from other countries, leakage from dumps, and the illegal use of old stocks. Related Program - Binational Program

Dieldrin
Dieldrin, a critical pollutant, was used as a pesticide for veterinary uses and to control soil insects. In the U.S. and Canada, its use is now restricted to termite control. Dieldrin has a long half-life in shallow waters compared to most chlorinated organic compounds. It is acutely toxic and poses a potential carcinogenic threat to humans. This chemical enters the Great Lakes System from the air or contaminated sediments and has been detected in fish and wildlife in all of the Great Lakes. Related Program - Binational Program

Dioxin TCDD
A critical pollutant considered to be highly toxic, 2,3,7,8 tetrachlorodibenzo-p-dioxin or TCDD is a variant in a family of 75 chlorinated organic compounds referred to as dioxins. An unwanted chemical byproduct of incineration and some industrial processes that use chlorine, dioxin tends to accumulate in the fatty tissue of fish. Dioxin is a suspected human carcinogen. Related Program - Binational Program

Discharge
Any release or unloading of a substance or materials from a pipe, or other emission source. The addition of any pollutant to the Waters of the State or to any disposal system from a point source. Related Programs - 40 CFR

Discharge of Dredged or Fill Material
Any addition of dredged or fill material into navigable waters or into the waters of the United States. This includes the driving of pilings and the addition of any material that changes the bottom elevation or configuration of a water body or material that might destroy or degrade any navigable water. Related Programs - Section 404, 33 CFR

Dry Deposition
The deposition of pollutants from the atmosphere that occurs during dry weather periods (such as dust and particulate matter). Dry deposition rates are often drastically different than wet deposition rates.

Duluth Seaway Port Authority
The Authority, consisting of seven members representing state, county, and city (Duluth) interests, promotes growth of international and domestic maritime commerce for Minnesota's World Port and strives to strengthen the financial condition of the Port while enhancing the regional economy through industrial development and construction of port facilities. The Authority co-sponsored, along with the Lake Carriers Association, the Voluntary Ballast Water Exchange Plan for the Control of Ruffe in Lake Superior.

Duluth-Superior Port Plan
A local program where the MN DNR is required to establish a port plan before it can authorize the filling of protected waters for port development. The plan includes provisions to protect designated natural resources areas, and to adopt a policy of no net loss for wetlands, fish habitat and aquatic communities in the St. Louis River and Estuary.