CONTROLLING SEDIMENT IN MINNESOTA SLIP

View an abstract of the project.

See a slideshow of the construction (10 slides).

• Storm sewer lines for the western end of downtown Duluth have been discharging excessively turbid, muddy water, often filled with trash, into the Duluth-Superior Harbor at the Minnesota Slip where the William Irvin Ore boat has been berthed for years.

• The high load of suspended sediment is the result of excessive stormwater runoff, wash off of winter sand, and erosion in the upper watershed. 

• The EPA’s Great Lakes National Program Office (GLNPO) funded a proposal submitted by the City of Duluth’s Stormwater Utility as a demonstration project for the sediment trap technology and to help protect the harbor from further water quality and habitat degradation.

• The slideshow shows the scale and expense (the whole project cost $250,000) of improving water quality at the point of discharge instead of preventing the problem at the source with better planning, and the many new options for minimizing runoff and erosion from individual homes and neighborhoods. Many of these are featured in the Site Design Toolkit section of the LakeSuperiorStreams.org website. The Regional Stormwater Protection Team was created to help educate people on how they can save money AND protect our streams and Lake Superior at the same time.

• A monitoring program will be set up to estimate how much sediment is removed by the trap and what fraction of the total load of sediment discharged to the harbor through the storm sewer is actually removed. Of course, this is just one of 42 streams in the City of Duluth that discharge to the harbor or directly to Lake Superior.