This summer’s drought has continued to draw down water levels in Lakes Superior and Michigan-Huron (hydrologically speaking, Michigan and Huron are the same body of water). New forecasts suggest that water levels in the two lakes may soon hit an all-time low, aggravating an economic quandary: with such low levels, cargo ships have to forgo millions of dollars of freight.
Last month 25 senators signed a letter calling on the federal Office of Management and Budget to devote more money to dredging the nation’s harbors. Federal taxes on ship cargo in coastal systems, including the Great Lakes, flow into a Harbor Maintenance Trust Fund, from which money is appropriated for operations and maintenance of harbors and ports, they noted.
Despite a balance of more than $8 billion, recent appropriations have averaged only $800 million, according to the letter.
“You hear the Great Lakes called a blue water highway,” said Chuck May, chairman of the Great Lakes Small Harbor Coalition, a dredging advocacy group. “I say to them what good is a superhighway if you don’t have any on or off ramps?”
Temporary or even permanent harbor closings could become more common if drought conditions continue. Last December, shipments to two ports in Michigan were canceled because shallow waters forced them to shut down.
When water levels approached record highs in 1997, the largest lake freighters were hauling 71,000 tons of cargo at a time. But all that tonnage weighs a ship down, and cargo loads declined after lake levels began a rapid decline in the late 1990’s.
When water levels approached record highs in 1997, the largest lake freighters were hauling 71,000 tons of cargo at a time. But all that tonnage weighs a ship down, and cargo loads declined after lake levels began a rapid decline in the late 1990’s.
“By the start of the 2000 navigation season, the biggest ships were lucky if they had 60,000 tons on board,” said Glen Nekvasil of the Lake Carriers Association, the trade group representing vessel operators in the Great Lakes that are registered under the United States flag. “So that’s when things really started to become critical.”
Since 1999, annual average water levels have been consistently below the historic averages recorded since 1860 in Lakes Superior and Michigan-Huron. A major research question for scientists is whether that trend will persist. Levels in Lakes Ontario and Erie have not fallen over the same period according to data from the Great Lakes Environmental Research Laboratory, and similar troughs during the 1930’s and 1960’s could suggest that this is a natural cycle.
But if the data are the beginning of a new normal, climate change could be the culprit, researchers say. Higher temperatures and receding ice cover might increase the rate of evaporation faster than precipitation and runoff can replenish the lakes.
Temperature-based computer models do suggest an increase in evaporation over the last 30 years, but researchers are only now verifying those results with direct measurements by gauges on remote lighthouses throughout the lakes.
At any rate, Great Lakes harbors are becoming shallower. The Army Corps of Engineers dredges more than two million cubic yards of mud and sand from Great Lakes ports each year, scooping out sediment flushed into the harbors by erosion along riverbanks and lakeshores. But the dredging has not kept up with demand.
Climate change could further complicate those operations by periodically increasing precipitation in the region. Lake Erie saw one of its largest-ever seasonal water level rises between February and June 2011 as result of record rainfall. More than 17 million cubic yards of excess sediment already clog the ports, with that amount expected to grow to 21 million cubic yards by 2015.
The 2012 federal budget calls for dredging on only 16 of the 63 federally maintained ports on the lakes. Even the top-priority harbors, those with about 90 percent of the commercial traffic, are adequately dredged only 35 percent of the time, according to estimates by the Army Corps of Engineers.
To industry representatives and port residents like Mr. May of the Great Lakes Small Harbor Coalition, it is an avoidable crisis. Mr. May started up the organization in 2007 after the sailboat Barracuda sank in his hometown while returning to Chicago after the annual yacht race to Mackinac Island. The ship gashed its keel in four feet of water after seeking refuge from storm conditions on Lake Michigan in a harbor that was supposed to have 18 feet of clearance.
“That’s when I got on the phone with other harbor communities,” Mr. May said, “and found out we all had the same problem.”
Ships delivering 500,000 tons of coal to a power plant in Dunkirk, N.Y., for example, began to skirt bottom so often that the port stopped receiving coal trade in 2005. The cargo now travels there by rail instead, albeit with a greater carbon footprint.
A portion of a documentary explaining part of why Great Lakes water levels are declining.
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