Steel sheet piling in the Duluth-Superior Harbor is corroding at an unusually accelerated rate. This rate of corrosion is similar to that commonly observed in saltwater ports, but not seen in freshwater environments. In addition, corrosion to this extent has not been documented in other Great Lakes ports and harbors. Based on observations of both older and new sheet pile installations, the increased rate of corrosion appears to have begun in the late 1970s.
A history of the Duluth-Superior Harbor corrosion research is included in a number of reports, spreadsheets and other peer-reviewed articles.
This succinct fact sheet provides a good summary of the Duluth-Superior Harbor accelerated harbor corrosion situation.