Great Lakes water levels are at historic lows, 26 inches below their long term averages, raising prices right at the beginning of the supply chain for iron ore, grain, and coal. For every inch the water levels fall, a freighter needs to leave another 100 tons of goods behind on the dock. That means one of the cheapest and most efficient ways to move freight in the world becomes less efficient and more expensive as the water levels drop.

It’s important to note that over 160 million tons of goods are carried on the Great Lakes each year, keeping our nation’s industrial belt supplied with raw materials. When ships carry less cargo, the cost per delivered unit increases even before the ore gets turned into steel, translating directly to higher cost for manufacturers and consumers.

Lakes Michigan and Huron have been below the historic average for 14 years now, and in January they fell to all time record low. They’ve gotten so low, 1013 foot “lakers” are having more difficulty navigating. They’re getting hung up on sand bars entering ports and are carrying up to 15 percent less capacity to make up for the lack of water. Shipping isn’t the only industry affected. The multi-million dollar charter fishing industry on the Great Lakes is also impacted as boats are unable to navigate the shallow channels.

The change in water levels is obvious to locals in the upper Great Lakes area (Lakes Michigan, Huron, and Superior). People living near the largest deep water port in Lake Michigan started finding fields of lumber tailings exposed by receding water, sunken remnants of the town’s lumbering era from over 120 years ago. In Grand Haven, Michigan a lost shipwreck showed above the falling water line for the first time in a century.

With little improvement in the water level outlook, the Lake Carriers Association and other groups have been left with little choice but to lobby legislators to improve dredging. Last month, Michigan’s Governor, Rick Snyder, approved $21 million in emergency dredging funds to keep the state's ports navigable. As I write this, a dredging operation is taking place right off the Muskegon channel. Meanwhile, scientists like Dr. Alan Steinman, Professor of Water Resources at Grand Valley State University, are calling for greater water conservation to offset water loss.

So what’s causing the long term drop in upper Great Lakes water levels?

The problem became so persistent the International Upper Great Lakes Study was formed in 2007 to initially research causes of water loss and remedial measures. They found a major contributing factor: human induced climate change combined with natural variation. A complex interplay of reduced ice cover in the winter and drier conditions means water in the Great Lakes is evaporating at an increased rate. Since 1973, the Great Lakes have lost 71 percent of their ice cover, leaving them exposed to winter evaporation.

In the near term, increased dredging and water conservation will keep the Great Lakes navigable. The long term, however, is far less certain.

[image credit: BaronSteffan: http://www.flickr.com/photos/baronsteffan/271841640/]