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Re: E-M:/ Granholm Puts Moratorium On Bottled Water Permits

Enviro-Mich message from Rane Curl <ranecurl@engin.umich.edu>

> This was released today by the governor.
> "Michigan is blessed to be surrounded by 20 percent of the world's fresh
> water supply, and we must not be reckless in protecting it," Granholm
> said.  "As stewards of the Great Lakes, we must ensure these facilities
> are not causing long term harm to our most precious natural resource."

This "20%" statement is often made as part of an argument for the
importance of the Great Lakes basin in terms of water conservation and
management. There is, however, some hazard to the resource in the claim,
and the truth is more complicated and worth noting.

It is true that the Great Lakes hold approximately 20% of the world's
fresh water *inventory*. The question is, to what extent is it a "supply"?

If the water is withdrawn for use and returned to the basin undiminished
in quality and quantity, then the "supply" is unlimited, and the fact that
the inventory is large is not relevant. The large inventory allows,
however, natural purification of water that is returned to the basin in
poor quality, at least for pollutants that time and natural processes can

If the water is withdrawn and not returned to the basin, the "supply" is
no more than the runoff. This is less than 2% of the world's fresh water
runoff. It is, for example, only a little more than 5% of the fresh water
runoff of the Amazon River basin.

I believe it is worth noting not only the large inventory of fresh water
in the Great Lakes basin, but also the much smaller "supply", as available
flow, which greatly amplifies both the impact of the pollution that flows
into the lakes and the effect of withdrawals on the fresh water inventory
in the lakes.

--Rane L Curl

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