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Lake Superior continues downward slide

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  • Mike Neuman
    Lake Superior continues downward slide By John Myers Forum Communications Published in the River Falls Journal January 5, 2007 The world s largest freshwater
    Message 1 of 1 , Jan 8, 2007
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      Lake Superior continues downward slide
      By John Myers
      Forum Communications
      Published in the River Falls Journal January 5, 2007

      The world's largest freshwater lake keeps getting smaller, inch by
      inch, as the worst drought in at least 30 years grips the Northland.

      The International Lake Superior Board of Control reported Wednesday
      that Lake Superior continued its decline through December and sits at
      its lowest Jan. 1 level in 81 years.

      The lake dropped two inches in December. It now sits a foot below the
      level it was at this time last year and more than 18 inches below the
      average for the month.

      So far, contrary to some media reports, the big lake's big drop
      hasn't set any monthly or all-time records. As low as it is now, Lake
      Superior is still three inches above its all-time January low and 10
      inches higher than the all-time record low set in April 1926.

      Even with the lake expected to drop through March, it's unlikely to
      fall below the 1926 record, said Cynthia Sellinger, a National
      Oceanic and Atmospheric Administration scientist at the Great Lakes
      Environmental Research Laboratory in Ann Arbor, Mich.

      "At this point, I don't see that happening," she said. "But that
      could change if it stays dry."

      Precipitation across the Lake Superior basin was only about 60
      percent of normal in December, although that's closer to normal than
      recent months. There has been less evaporation because of fewer cold
      snaps, which pull moisture from the lake.

      "The lake actually declined a little less than normal in December.
      But not much less," said Carl Woodruff, a hydraulic engineer for the
      U.S. Army Corps of Engineers Detroit District.

      Lake Superior is so huge that the decline has been hard to notice to
      the untrained eye. Even at 18 inches below the long-term average, the
      lake doesn't look much different to most people.

      Park Point residents are noticing a wider-than-ever beach. And Great
      Lakes freighters are traveling with less-than-full loads because
      water levels in harbors are so low. That means thousands of dollars
      more to move the same amount of coal, taconite and grain – millions
      of dollars spread across the hundreds of vessels on the lakes.

      Environmentally, low water levels shouldn't have much effect on Lake
      Superior, and may even help prevent erosion along sensitive
      shoreline. But the drought has affected the lake's tributary streams,
      where some salmon and trout spawn. North and South Shore streams are
      running at near-historic low seasonal levels, as are most rivers in
      northern Minnesota.

      While heavy rain last weekend will help soften the drought, it's far
      from over. The National Drought Mitigation Center is forecasting the
      region's extreme drought to continue through March before any relief
      comes.

      Some northern Minnesota areas had their lowest rainfall levels in
      recorded history during the past growing season, from May to October.
      So far this year, snow-depth rankings have been off the charts — the
      sparsest December snow cover ever in some places.

      "If the next 90-day forecast is the same as the current one, then
      we'll see a continued decline in the lake's level," Sellinger
      said. "You've got very little snowpack. The levels already are low.

      And if there's not the usual spring rains, that's not a good
      combination. At this point, I'm not seeing much of a spring runoff
      increase (in water levels) like we would normally get."

      With a warmer and dryer than normal Northland winter forecast through
      March, the prognosis for relief isn't great. Evaporation across the
      lake's 31,700-square-mile surface area will continue to suck water
      out of the lake, especially with little or no ice cover — thanks to
      unusually warm weather. Woodruff said occasional blasts of cold air
      across the unfrozen lake will pull even more moisture out of Lake
      Superior and deposit it on land as lake-effect snow. Much of that
      moisture returns to the lake, but there's no net gain.

      "What we need are some big storms to come in from the west to bring
      in new moisture," Woodruff said. "Since early summer, Lake Superior
      has been just starved of moisture."

      A new study by the International Joint Commission will try to
      determine whether the decline is part of a larger pattern. The report
      will look at the impact of weather cycles, climate change and how the
      lake's outlet at Saulte Ste. Marie is controlled. That outlet
      determines how much water can be used for hydroelectric power
      generation and how much moves into the lower lakes.

      The study also will look at whether a dredging project on the St.
      Clair River in 1962, which allowed more water to leave lakes Huron
      and Michigan, has contributed to low water levels. When the river was
      dredged to 30 feet deep allow heavier ships to pass, erosion scoured
      parts of the river to more than 60 feet deep. Some say that has
      opened a wider funnel out of the upper lakes. But because the lake's
      record high came in the 1980s, after the dredging, skeptics say
      climate variations — not dredging — are the primary factor in Lake
      Superior water levels.

      Others say a contributing factor could be the ongoing settling of the
      earth below the Great Lakes, still changing after the last glacial
      period and tilting more water out of the basin.
      http://www.greatlakesdirectory.org/wi/010507_great_lakes.htm
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