Thursday, February 21, 2013

Rain Needed in Great Lakes and Mississippi River

Heavy snows haven’t done much to help the Mississippi River or the upper Great Lakes. Snow, it turns out, is no substitute for rain. The middle Mississippi River has risen by a few inches, above the range where it might be closed to shipping, but it will need a few summer-like storms to stay open through the spring. Meanwhile, Lake Huron/Michigan has fallen below its previously recorded low, and it will need years of near-normal precipitation to avoid major shipping restrictions from low water levels. In both places, evaporation has also been a major factor in removing the water. A few cooler, cloudier summers, with less surface evaporation, would help too.

In the short run, clearing the bottoms of waterways may be the only answer. A project to remove boulders from the Mississippi River bottom in a particularly sensitive area was completed last week, and in Lake Huron/Michigan, and to a lesser extent in Lake Superior, dozens of projects are planned to dredge harbors and channels so that fully loaded cargo ships can get through.