Re: turnover of water in Crater Lake

["Dukelow, James S Jr" <jim.dukelow@pnl.gov>]

On Wed, 16 Feb 2000 20:24:57 +0100
Franz Schoenhofer <schoenho@via.at> wrote:

At 10:25 15.02.2000 -0600, you wrote:
>Doug --
>
>The 'dating' of ground water or snow packs is possible where there is little
>or no addition of 'new' water, or where the kinetics of 'new' water addition
>are known.  For example, Crater Lake in Oregon does not have water tunover,

Does it never rain there and does the water not evaporate? I do not know
this Crater Lake nor how deep it is, but as we know well from the oceans,
tritium concentration varies with depth and this should be especially true,
when there is no water turnover and the more recent precipitation will
dilute the water close to the surface.
	<snip>
Franz


Jim Dukelow comments:

Franz is right to be sceptical.  If Crater Lake had no turnover, it would be
"dead" like the Dead Sea and similar lakes around the world.

Crater Lake has moisture input from rain and snow and "output" by seepage
through the volcanic tuff that the mountain is built from.  The outer slopes of
the mountain (Mount Mazama before it blew its top around 6000 years ago -- I'm
not sure what it is called now) have numerous spring sources.  Water will be
removed from the sides and bottom of the lake.  From its position in the
Southern Cascade mountains, I would guess that it gets about 120 inches (3 m) of
moisture input per year.  The climate at the lake is cool in the summer and cold
in the winter, so evaporation is probably minimal.  Average depth of the lake is
around 1000 feet (300 m), so average residence time of water in the lake should
be on the order of 100 years.  I have no idea how well-mixed the water in the
lake is.

Best regards.

Jim Dukelow
Pacific Northwest National Laboratory
Richland, WA
jim.dukelow@pnl.gov

These comments are mine and have not been reviewed and/or approved by my
management or by the U.S. Department of Energy.
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