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Re: E-M:/ Lake levels/wells



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Enviro-Mich message from Barbara Jean Madsen <bjmadsen@biology.lsa.umich.edu>
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On Tue, 28 Mar 2000, Kristine Yvette Olsson wrote:

> -------------------------------------------------------------------------
> Enviro-Mich message from Kristine Yvette Olsson <olssonk@umich.edu>
> -------------------------------------------------------------------------
> 
> We are also getting some calls asking about low lake and river levels.  We
> are going to be writing and article on it, actually, for our next
> newsletter.  We would like to address why levels are low (cyclic droughts?
> Global warming? Development paving over groundwater recharge areas) and
> what, if anything people should or should not do about it.

The lakes do go up and down on a natural 7-10 - year cycle, related to
cycles of precipitation.  The record low was in the mid-1960s; the record
high was in 1986.  There has also been a long-term trend upward, so that
the record low of the 60s wasn't expected to be exceeded.  I don't know if
anyone has definitely established the reason for the magnitude of the
current low, but global warming/climate change, together with El Nino, is
probably involved.

	It should be pointed out that the cycles of lake levels are
essential to the health and even the existence of the Great Lakes coastal
marshes, which are among the most diverse (in terms of plant species) and
productive ecosystems in the world, and which support many fish and bird
species as well.  In low-water years, seeds in the soil germinate and give
rise to many plants of moist ground and shallow water.  As low water
persists, woody plants (shrubs and trees) invade and would take over the
marsh, but in the high-water years, the woody plants are drowned out,
clearing the ground for the succession of marsh plants to begin again.
Thus, stabilizing the levels of the lakes would cause widespread
ecological damage.

	--Barb Madsen






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