Despite spring floods and worrisome trade tariffs, the Port of Duluth-Superior enjoyed a surge of cargo shipments in August amid large orders of Midwest wheat and Minnesota iron ore.

While flooding delayed the planting of many spring crops, grain shipments at the end of the harvest season actually jumped 5% from a year ago amid large yields from ag producers across western Minnesota and North and South Dakota, the Chamber of Marine Commerce reported on Tuesday.

Shipments of taconite iron-ore pellets also rose, signaling that the ore-industry recovery is again on solid shores after the dreadful global downturns of 2015 and 2016 that idled seven ore plants across Minnesota's Iron Range.

"Cargo movement in the Port of Duluth-Superior remained brisk through August. Iron ore led the way, finishing the month more than 15 percent ahead of the five-year average and within 2 percent of last season's pace, which was a 23-season high," said Duluth Seaway Port Authority spokesman Jayson Hron in a statement. "We also welcomed several shipments of wind energy cargo in August, continuing a near-record pace for that particular cargo."

The robust activity out of Lake Superior contributed to a busy month for many of the U.S. Great Lakes ports as shipments of construction materials, road salt, aluminum and wind-energy components also filled the waterways that stretch from Minnesota to the Atlantic Ocean.

In addition to the Port of Duluth-Superior, cargo gains were particularly strong for the ports of Toledo and Green Bay.

"Great Lakes ports have been busy moving cargo supporting the construction and renewable-energy sectors. Aluminum shipments from Canada to the U.S., which are used in automotive manufacturing, have also resumed this season following the lifting of trade tariffs," said Chamber of Marine Commerce President Bruce Burrows.

However, his report was not all good news.

Total "binational" cargo volumes between the United States and Canada that traveled the St. Lawrence Seaway fell 3.5% to 20.9 million metric tons from a year ago for the period spanning March 22 to Aug. 31.

Burrows explained that the overall gains seen along the entire St. Lawrence Seaway "have been offset by a 20 percent decline in U.S. grain exports via the St. Lawrence Seaway after flooding this past spring prevented some U.S. farmers from getting into their fields to plant corn and soybeans."