A Canadian power company's decision to go green resulted in lower waterborne cargo totals passing through the Twin Ports this season, even though iron ore and other cargoes were up.

The Poe Lock at Sault Ste. Marie, Mich., will close at midnight Wednesday, signifying the end of the Great Lakes shipping season. While the Duluth Seaway Port Authority doesn't have final numbers for the 2011 shipping season yet, they have a pretty good idea how it will finish.

"We are going to be down about 6 to 7 percent from 2010 numbers," said Adolph Ojard, Duluth Seaway Port Authority executive director. "The bright spot is iron ore, which is a huge economic driver for the region."

But while taconite shipments were up this year, coal and grain shipments were down.

Coal is an important cargo in the Twin Ports.

Despite the regional connection of iron ore and the port, the tonnage of coal traveling through the port actually outpaced iron ore in seven of the last 10 shipping seasons, including a six-year run from 2005 through the 2010 season.