Water levels on Lake Superior continue moving toward record lows. January saw a four-inch drop, an inch more than usual for this time of year. The current water level is 18 inches below normal and 14 inches below last February's level. The forecast for lake levels for the start of the shipping season looks bleak as one of the Lake Superior basin's most extensive droughts continues. Lake levels could approach the record low of 1926.

These figures indicate that a tremendous volume of water has gone missing. According to a recent calculation, one inch of water on Lake Superior equals all the water in Lake Mill Lacs, the second largest lake in Minnesota, at 132,516 acres. For the maritime shipping industry, the effects of lower water levels in Lake Superior will be significant.

The draft of a ship, defined as "the depth to which a vessel is submerged", is directly related to the cargo it carries. A ship's draft is limited to its design capacity or the depth of the water/channels it must move through (whichever is less). At the end of the last shipping season, ships that historically loaded to 27.5 feet sailed from Duluth with a 26-foot draft. The draft was restricted by three critical voyage areas: Vidal Shoals west of the Soo Locks on the down-bound approach, Little Rapids, and the Rock Cut east of the Soo Locks in the lower St. Mary's River.

Depth at Vidal Shoals is controlled by Lake Superior water levels, and Little Rapids and Rock Cut depths are controlled by Lake Michigan/Lake Huron levels. Five years ago the industry pushed to deepen the Vital Shoals channel. Had that not been done, the near record low water levels of Lake Superior would have had an even more profound impact on vessel voyage drafts.

So what has the impact been? The last shipping season represented the third consecutive year of increased tonnage for the Twin Ports of Duluth-Superior and the best tonnage year since 1978. Last year 1,050 U.S. and Canadian flagged ships called on the Twin Ports of Duluth-Superior. While the Port's annual Great Lakes tonnage increased by 1.1 million net tons, vessel calls increased disproportionately by 42. The average cargo per ship decreased 681 net tons, or 1.5 percent.

Put another way if we look at the voyage capacity of the U.S. flagged domestic fleet, each inch of restricted draft reduces the fleet's voyage capacity by 8,000 net tons. If there are 50 voyages each year, there is a seasonal impact of 400,000 net tons per inch. Multiplying that number by the 18 inches Lake Superior is below normal means the U.S. flagged fleet has a reduced annual capacity of 7.2 million net tons. This is a serious constraint on the Great Lakes System's ability to meet future needs.

It means that more vessel calls are required to move regional freight.  Given the fixed number of ships in U.S. and Canadian service, there may soon arrive a time when freight will be left at the dock at the end of the season. That freight would shift to truck and rail at a higher price or not move at all, disrupting industry here and elsewhere as well.

The industry could build more ships, but under these conditions the huge investment required would not show an adequate return. If global warming is indeed fact, serious consideration could be give to extending the shipping season to increase the number of vessel voyages. Or the industry could ask that the Great Lakes Waterway be recognized in Washington, D.C., as a vital national interest and that the Corps of Engineers budget be increased to provide adequate dredging of the System's harbors and connecting channels. To that end, the Great Lakes Task Force has been re-energized to focus on the need for dredging (See Pages 4-5).

Should we be unsuccessful with our dredging efforts, I propose a national program of "Keels on Wheels." We would roll the ships over the shoals, high spots and shallows. This program would permit the ships to load deeper, carry more tonnage, maintain profitability and avoid shifting maritime cargo to an already congested landside transportation system.

As a practical matter, this approach is insane, but "Keels on Wheels" does have a nice ring to it -and it also brings attention to the critical issues of dredging and climate change.