Tuesday, October 25, 2011


Algae and scale shading on steel sheets, indicating
annual lake level variations, with highest point
resulting from the 1986-87 modern high. 
Washington Island, Wisconsin -

tide |tīd|nounthe alternate rising and falling of the sea, usually twice in each lunar day at a particular place, due to the attraction of the moon and sun: the changing patterns of the tides | they were driven on by wind and tide.• the water as affected by this: the rising tide covered the wharf.• a powerful surge of feeling or trend of events: he drifted into sleep on a tide of euphoria | we must reverse the growing tide of racism sweeping the country.

Ticket seller Maggie Swanson fielded a challenging question yesterday from a visitor.  His question was:  "Is it high tide right now, or low tide?"

If there are tides on Lake Michigan, they are imperceptible.  However, with mud flats and protruding rocks now beginning to show a bit more each week, our harbors and shorelines do take on an appearance of lake water having ebbed with the tide.   This phenomena is typically observed here in the fall of the year.  Lake Michigan levels have remained below-average since approximately 2001, and for some of those years the levels have been mere inches above the record-lows of 1963-64.  

According to a report received from the International Lake Superior Board of Control, under authority of the International Joint Commission (IJC), the Lake Superior outflow has once again been adjusted, one means of tweaking water levels in lakes Huron and Michigan which, by the Mackinac Straits connection, are at the same levels.  Lake Superior by the end of September was about 11 inches below long-term average, but 2 inches higher than a year ago.  Lakes Michigan-Huron at that same time were about 14 inches below long-term average, 1-inch lower than a year ago, and about 7 inches above chart datum level.

Low water observed on Lakes Michigan-Huron has drawn critics for past engineering and the processes by which water levels are adjusted and maintained.   Yet, from all we've read and heard, including a presentation by the IJC Chairman several summers back, there is nothing as dramatic for impact on lake levels as plentiful precipitation, or on the other hand, evaporation, and absorption into land mass.

We were told that despite the controls at the few man-made valves from these Great Lakes, mother nature is still very much in control, and she will continue to dictate what is normal despite our wishes to the contrary.  Would an "empathy table"and free hugs, such as that employed by Wall Street protestors at New York City's Zuccotti Park, be useful activism for citizens who refuse to believe Army Corps of Engineers (ACE) data and reasoning?   An empathy table would provide temporary mental relief, at least, from what may seem to be overwhelmingly difficult and unfair conditions.

U.S. ACE Great Lakes Update

Monthly our office receives a free report on Great Lakes water levels, which includes a very informative bulletin titled "Great Lakes Update."

According to October's bulletin, the Coordinating Committee on Basic Hydraulic and Hydrology Data was formed in 1953, following extremely high lake levels in 1952.   At that time, agencies in both the U.S. and Canada "recognized that continued independent development of basic data would be illogical...and that early agreement on the hydraulic and hydrologic characteristics of the system was of paramount importance..."    As a result they "...opened negotiations early in 1953 for the purposes of establishing a basis for development and acceptance of identical data by both countries."

The Coordinating Committee, which meets twice a year, is made up of six members  (a chairperson, member and secretary from each country) and represents these agencies:
  *  U.S. Army Corps of Engineers
  *  National Oceanic and Atmospheric Administration
  *   U.S. Geologic Survey
  *   Environment Canada
  *   Natural Resources Canada
  *  Fisheries and Oceans Canada
  *  Canadian Hydrographic Service

There are several important subcommittees (pardon me if your eyes begin to glaze slightly as we review them):

    **   The Vertical Control-Water Levels Subcommittee which established the International Great Lakes Datum (IGLD) in 1955, a base line for all future measurements.   Noted are the "continued effects of crustal movements," new surveying methods, and the deterioration of the "zero reference point gauge location."

   **  The Hydraulics Subcommittee, which documents methods for conducting hydraulic field measurements, reports them, makes maps, comments on measurement techniques and computation methods, water level readings and tables of actual discharges.

   **  The Hydrology Subcommittee "spends a great deal of effort in coordinating forecasted wear levels for the Great Lakes and official water level statistics," which includes discussion of "Monthly mean water levels, outflows, precipitation and net basin supplies..."

The above is but a summary of the activities of the IJC and its subcommittees, a rather impressive range of activities for which the average citizen has little appreciation.  It is something to think about when gazing at the mud flats and wondering, and complaining, "Where has all the water gone?"

We can take comfort in the fact that these impressive-sounding agencies, staffed and supported by many technical experts in their field, put their best effort forward in monitoring and managing our Great Lakes water.  While their activities are tax-payer funded, and they work from a framework of legislation approved by Canada and the U.S., there would seem to me to be little room in such settings for renegades or persons with self-serving motives.  And still, these agencies have come under increasing pressure in recent years from those who aim for the good old days of higher lake levels, and who desire to change the status quo (to what?).

Bring on the "Empathy Table" and free hugs.  We can all use some!
 -  Dick Purinton

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