ENVIRONMENTAL EFFECTS OF HARBOR DREDGING DULUTH-SUPERIOR

Abstract

The Duluth-Superior harbor is a natural port created as a result of the formation of a unique bay mouth sand bar which, over a period of years, has been modified into two points .of land termed Minnesota and Wisconsin Point. The harbor is complex area which acts as. a receiving area for the waters and sediment load of two major streams, the Saint Louis forming the Minnesota and Wisconsin state line, and the Nemadji. While the former is considered to be the carrier of significant amounts of industrial effluent the latter is a very important transporter of suspended Pleistocene-aged red clay. As the Saint Louis flows into the Duluth portion of the harbor its natural flow path turns to the southeast and joins the outflow of the Nemadji before exiting into Lake Superior through the Superior entry.